blob: 642d8805bc1bb967f03715d3585a9cd0fa99e5bb [file] [log] [blame]
Rusty Russellf938d2c2007-07-26 10:41:02 -07001/*P:010
2 * A hypervisor allows multiple Operating Systems to run on a single machine.
3 * To quote David Wheeler: "Any problem in computer science can be solved with
4 * another layer of indirection."
Rusty Russell07ad1572007-07-19 01:49:22 -07005 *
Rusty Russellf938d2c2007-07-26 10:41:02 -07006 * We keep things simple in two ways. First, we start with a normal Linux
7 * kernel and insert a module (lg.ko) which allows us to run other Linux
8 * kernels the same way we'd run processes. We call the first kernel the Host,
9 * and the others the Guests. The program which sets up and configures Guests
Rob Landley61516582011-05-06 09:27:36 -070010 * (such as the example in Documentation/virtual/lguest/lguest.c) is called the
Rusty Russellf938d2c2007-07-26 10:41:02 -070011 * Launcher.
12 *
Rusty Russella6bd8e12008-03-28 11:05:53 -050013 * Secondly, we only run specially modified Guests, not normal kernels: setting
14 * CONFIG_LGUEST_GUEST to "y" compiles this file into the kernel so it knows
15 * how to be a Guest at boot time. This means that you can use the same kernel
16 * you boot normally (ie. as a Host) as a Guest.
Rusty Russellf938d2c2007-07-26 10:41:02 -070017 *
18 * These Guests know that they cannot do privileged operations, such as disable
19 * interrupts, and that they have to ask the Host to do such things explicitly.
20 * This file consists of all the replacements for such low-level native
21 * hardware operations: these special Guest versions call the Host.
22 *
Rusty Russella6bd8e12008-03-28 11:05:53 -050023 * So how does the kernel know it's a Guest? We'll see that later, but let's
24 * just say that we end up here where we replace the native functions various
Rusty Russell2e04ef72009-07-30 16:03:45 -060025 * "paravirt" structures with our Guest versions, then boot like normal.
26:*/
Rusty Russellf938d2c2007-07-26 10:41:02 -070027
28/*
Rusty Russell07ad1572007-07-19 01:49:22 -070029 * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
30 *
31 * This program is free software; you can redistribute it and/or modify
32 * it under the terms of the GNU General Public License as published by
33 * the Free Software Foundation; either version 2 of the License, or
34 * (at your option) any later version.
35 *
36 * This program is distributed in the hope that it will be useful, but
37 * WITHOUT ANY WARRANTY; without even the implied warranty of
38 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
39 * NON INFRINGEMENT. See the GNU General Public License for more
40 * details.
41 *
42 * You should have received a copy of the GNU General Public License
43 * along with this program; if not, write to the Free Software
44 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
45 */
46#include <linux/kernel.h>
47#include <linux/start_kernel.h>
48#include <linux/string.h>
49#include <linux/console.h>
50#include <linux/screen_info.h>
51#include <linux/irq.h>
52#include <linux/interrupt.h>
Rusty Russelld7e28ff2007-07-19 01:49:23 -070053#include <linux/clocksource.h>
54#include <linux/clockchips.h>
Rusty Russell07ad1572007-07-19 01:49:22 -070055#include <linux/lguest.h>
56#include <linux/lguest_launcher.h>
Rusty Russell19f15372007-10-22 11:24:21 +100057#include <linux/virtio_console.h>
Jeff Garzik4cfe6c32007-10-25 14:15:09 +100058#include <linux/pm.h>
Paul Gortmaker39a0e332011-07-21 13:03:20 -040059#include <linux/export.h>
Ingo Molnar7b6aa332009-02-17 13:58:15 +010060#include <asm/apic.h>
Harvey Harrisoncbc34972008-02-13 13:14:35 -080061#include <asm/lguest.h>
Rusty Russell07ad1572007-07-19 01:49:22 -070062#include <asm/paravirt.h>
63#include <asm/param.h>
64#include <asm/page.h>
65#include <asm/pgtable.h>
66#include <asm/desc.h>
67#include <asm/setup.h>
68#include <asm/e820.h>
69#include <asm/mce.h>
70#include <asm/io.h>
Jes Sorensen625efab2007-10-22 11:03:28 +100071#include <asm/i387.h>
Rusty Russell2cb78782009-06-03 14:52:24 +093072#include <asm/stackprotector.h>
Balaji Raoec04b132007-12-28 14:26:24 +053073#include <asm/reboot.h> /* for struct machine_ops */
Rusty Russell89cfc992011-10-27 10:56:17 +103074#include <asm/kvm_para.h>
Rusty Russell07ad1572007-07-19 01:49:22 -070075
Rusty Russell9f542882011-07-22 14:39:50 +093076/*G:010
77 * Welcome to the Guest!
Rusty Russellb2b47c22007-07-26 10:41:02 -070078 *
79 * The Guest in our tale is a simple creature: identical to the Host but
80 * behaving in simplified but equivalent ways. In particular, the Guest is the
Rusty Russell2e04ef72009-07-30 16:03:45 -060081 * same kernel as the Host (or at least, built from the same source code).
82:*/
Rusty Russellb2b47c22007-07-26 10:41:02 -070083
Rusty Russell07ad1572007-07-19 01:49:22 -070084struct lguest_data lguest_data = {
85 .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
86 .noirq_start = (u32)lguest_noirq_start,
87 .noirq_end = (u32)lguest_noirq_end,
Rusty Russell47436aa2007-10-22 11:03:36 +100088 .kernel_address = PAGE_OFFSET,
Rusty Russell07ad1572007-07-19 01:49:22 -070089 .blocked_interrupts = { 1 }, /* Block timer interrupts */
Rusty Russellc18acd72007-10-22 11:03:35 +100090 .syscall_vec = SYSCALL_VECTOR,
Rusty Russell07ad1572007-07-19 01:49:22 -070091};
Rusty Russell07ad1572007-07-19 01:49:22 -070092
Rusty Russell2e04ef72009-07-30 16:03:45 -060093/*G:037
94 * async_hcall() is pretty simple: I'm quite proud of it really. We have a
Rusty Russellb2b47c22007-07-26 10:41:02 -070095 * ring buffer of stored hypercalls which the Host will run though next time we
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -060096 * do a normal hypercall. Each entry in the ring has 5 slots for the hypercall
Rusty Russellb2b47c22007-07-26 10:41:02 -070097 * arguments, and a "hcall_status" word which is 0 if the call is ready to go,
98 * and 255 once the Host has finished with it.
99 *
100 * If we come around to a slot which hasn't been finished, then the table is
101 * full and we just make the hypercall directly. This has the nice side
102 * effect of causing the Host to run all the stored calls in the ring buffer
Rusty Russell2e04ef72009-07-30 16:03:45 -0600103 * which empties it for next time!
104 */
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100105static void async_hcall(unsigned long call, unsigned long arg1,
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600106 unsigned long arg2, unsigned long arg3,
107 unsigned long arg4)
Rusty Russell07ad1572007-07-19 01:49:22 -0700108{
109 /* Note: This code assumes we're uniprocessor. */
110 static unsigned int next_call;
111 unsigned long flags;
112
Rusty Russell2e04ef72009-07-30 16:03:45 -0600113 /*
114 * Disable interrupts if not already disabled: we don't want an
Rusty Russellb2b47c22007-07-26 10:41:02 -0700115 * interrupt handler making a hypercall while we're already doing
Rusty Russell2e04ef72009-07-30 16:03:45 -0600116 * one!
117 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700118 local_irq_save(flags);
119 if (lguest_data.hcall_status[next_call] != 0xFF) {
120 /* Table full, so do normal hcall which will flush table. */
Rusty Russell091ebf02010-04-14 21:43:54 -0600121 hcall(call, arg1, arg2, arg3, arg4);
Rusty Russell07ad1572007-07-19 01:49:22 -0700122 } else {
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000123 lguest_data.hcalls[next_call].arg0 = call;
124 lguest_data.hcalls[next_call].arg1 = arg1;
125 lguest_data.hcalls[next_call].arg2 = arg2;
126 lguest_data.hcalls[next_call].arg3 = arg3;
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600127 lguest_data.hcalls[next_call].arg4 = arg4;
Rusty Russellb2b47c22007-07-26 10:41:02 -0700128 /* Arguments must all be written before we mark it to go */
Rusty Russell07ad1572007-07-19 01:49:22 -0700129 wmb();
130 lguest_data.hcall_status[next_call] = 0;
131 if (++next_call == LHCALL_RING_SIZE)
132 next_call = 0;
133 }
134 local_irq_restore(flags);
135}
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100136
Rusty Russell2e04ef72009-07-30 16:03:45 -0600137/*G:035
138 * Notice the lazy_hcall() above, rather than hcall(). This is our first real
139 * optimization trick!
Rusty Russell633872b2007-11-05 21:55:57 +1100140 *
141 * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
142 * them as a batch when lazy_mode is eventually turned off. Because hypercalls
143 * are reasonably expensive, batching them up makes sense. For example, a
144 * large munmap might update dozens of page table entries: that code calls
145 * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
146 * lguest_leave_lazy_mode().
147 *
148 * So, when we're in lazy mode, we call async_hcall() to store the call for
Rusty Russell2e04ef72009-07-30 16:03:45 -0600149 * future processing:
150 */
Rusty Russell091ebf02010-04-14 21:43:54 -0600151static void lazy_hcall1(unsigned long call, unsigned long arg1)
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200152{
153 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
Rusty Russell091ebf02010-04-14 21:43:54 -0600154 hcall(call, arg1, 0, 0, 0);
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200155 else
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600156 async_hcall(call, arg1, 0, 0, 0);
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200157}
158
Rusty Russella91d74a2009-07-30 16:03:45 -0600159/* You can imagine what lazy_hcall2, 3 and 4 look like. :*/
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200160static void lazy_hcall2(unsigned long call,
Rusty Russell091ebf02010-04-14 21:43:54 -0600161 unsigned long arg1,
162 unsigned long arg2)
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200163{
164 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
Rusty Russell091ebf02010-04-14 21:43:54 -0600165 hcall(call, arg1, arg2, 0, 0);
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200166 else
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600167 async_hcall(call, arg1, arg2, 0, 0);
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200168}
169
170static void lazy_hcall3(unsigned long call,
Rusty Russell091ebf02010-04-14 21:43:54 -0600171 unsigned long arg1,
172 unsigned long arg2,
173 unsigned long arg3)
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100174{
175 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
Rusty Russell091ebf02010-04-14 21:43:54 -0600176 hcall(call, arg1, arg2, arg3, 0);
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100177 else
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600178 async_hcall(call, arg1, arg2, arg3, 0);
179}
180
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600181#ifdef CONFIG_X86_PAE
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600182static void lazy_hcall4(unsigned long call,
Rusty Russell091ebf02010-04-14 21:43:54 -0600183 unsigned long arg1,
184 unsigned long arg2,
185 unsigned long arg3,
186 unsigned long arg4)
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600187{
188 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
Rusty Russell091ebf02010-04-14 21:43:54 -0600189 hcall(call, arg1, arg2, arg3, arg4);
Matias Zabaljaureguicefcad12009-06-12 22:27:07 -0600190 else
191 async_hcall(call, arg1, arg2, arg3, arg4);
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100192}
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600193#endif
Rusty Russell633872b2007-11-05 21:55:57 +1100194
Rusty Russella91d74a2009-07-30 16:03:45 -0600195/*G:036
Rusty Russell9f542882011-07-22 14:39:50 +0930196 * When lazy mode is turned off, we issue the do-nothing hypercall to
197 * flush any stored calls, and call the generic helper to reset the
198 * per-cpu lazy mode variable.
199 */
Jeremy Fitzhardingeb407fc52009-02-17 23:46:21 -0800200static void lguest_leave_lazy_mmu_mode(void)
Rusty Russell633872b2007-11-05 21:55:57 +1100201{
Rusty Russell091ebf02010-04-14 21:43:54 -0600202 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
Jeremy Fitzhardingeb407fc52009-02-17 23:46:21 -0800203 paravirt_leave_lazy_mmu();
204}
205
Rusty Russell9f542882011-07-22 14:39:50 +0930206/*
207 * We also catch the end of context switch; we enter lazy mode for much of
208 * that too, so again we need to flush here.
209 *
210 * (Technically, this is lazy CPU mode, and normally we're in lazy MMU
211 * mode, but unlike Xen, lguest doesn't care about the difference).
212 */
Jeremy Fitzhardinge224101e2009-02-18 11:18:57 -0800213static void lguest_end_context_switch(struct task_struct *next)
Jeremy Fitzhardingeb407fc52009-02-17 23:46:21 -0800214{
Rusty Russell091ebf02010-04-14 21:43:54 -0600215 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
Jeremy Fitzhardinge224101e2009-02-18 11:18:57 -0800216 paravirt_end_context_switch(next);
Rusty Russell633872b2007-11-05 21:55:57 +1100217}
Rusty Russell07ad1572007-07-19 01:49:22 -0700218
Rusty Russell61f4bc82009-06-12 22:27:03 -0600219/*G:032
Rusty Russelle1e72962007-10-25 15:02:50 +1000220 * After that diversion we return to our first native-instruction
221 * replacements: four functions for interrupt control.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700222 *
223 * The simplest way of implementing these would be to have "turn interrupts
224 * off" and "turn interrupts on" hypercalls. Unfortunately, this is too slow:
225 * these are by far the most commonly called functions of those we override.
226 *
227 * So instead we keep an "irq_enabled" field inside our "struct lguest_data",
228 * which the Guest can update with a single instruction. The Host knows to
Rusty Russella6bd8e12008-03-28 11:05:53 -0500229 * check there before it tries to deliver an interrupt.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700230 */
231
Rusty Russell2e04ef72009-07-30 16:03:45 -0600232/*
233 * save_flags() is expected to return the processor state (ie. "flags"). The
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100234 * flags word contains all kind of stuff, but in practice Linux only cares
Rusty Russell2e04ef72009-07-30 16:03:45 -0600235 * about the interrupt flag. Our "save_flags()" just returns that.
236 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700237static unsigned long save_fl(void)
238{
239 return lguest_data.irq_enabled;
240}
Rusty Russell07ad1572007-07-19 01:49:22 -0700241
Rusty Russellb2b47c22007-07-26 10:41:02 -0700242/* Interrupts go off... */
Rusty Russell07ad1572007-07-19 01:49:22 -0700243static void irq_disable(void)
244{
245 lguest_data.irq_enabled = 0;
246}
Rusty Russell61f4bc82009-06-12 22:27:03 -0600247
Rusty Russell2e04ef72009-07-30 16:03:45 -0600248/*
249 * Let's pause a moment. Remember how I said these are called so often?
Rusty Russell61f4bc82009-06-12 22:27:03 -0600250 * Jeremy Fitzhardinge optimized them so hard early in 2009 that he had to
251 * break some rules. In particular, these functions are assumed to save their
252 * own registers if they need to: normal C functions assume they can trash the
253 * eax register. To use normal C functions, we use
254 * PV_CALLEE_SAVE_REGS_THUNK(), which pushes %eax onto the stack, calls the
Rusty Russell2e04ef72009-07-30 16:03:45 -0600255 * C function, then restores it.
256 */
Rusty Russell61f4bc82009-06-12 22:27:03 -0600257PV_CALLEE_SAVE_REGS_THUNK(save_fl);
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -0800258PV_CALLEE_SAVE_REGS_THUNK(irq_disable);
Rusty Russellf56a3842007-07-26 10:41:05 -0700259/*:*/
Rusty Russell61f4bc82009-06-12 22:27:03 -0600260
261/* These are in i386_head.S */
262extern void lg_irq_enable(void);
263extern void lg_restore_fl(unsigned long flags);
264
Rusty Russell2e04ef72009-07-30 16:03:45 -0600265/*M:003
Rusty Russella91d74a2009-07-30 16:03:45 -0600266 * We could be more efficient in our checking of outstanding interrupts, rather
267 * than using a branch. One way would be to put the "irq_enabled" field in a
268 * page by itself, and have the Host write-protect it when an interrupt comes
269 * in when irqs are disabled. There will then be a page fault as soon as
270 * interrupts are re-enabled.
Rusty Russella6bd8e12008-03-28 11:05:53 -0500271 *
272 * A better method is to implement soft interrupt disable generally for x86:
273 * instead of disabling interrupts, we set a flag. If an interrupt does come
274 * in, we then disable them for real. This is uncommon, so we could simply use
Rusty Russell2e04ef72009-07-30 16:03:45 -0600275 * a hypercall for interrupt control and not worry about efficiency.
276:*/
Rusty Russell07ad1572007-07-19 01:49:22 -0700277
Rusty Russellb2b47c22007-07-26 10:41:02 -0700278/*G:034
279 * The Interrupt Descriptor Table (IDT).
280 *
281 * The IDT tells the processor what to do when an interrupt comes in. Each
282 * entry in the table is a 64-bit descriptor: this holds the privilege level,
283 * address of the handler, and... well, who cares? The Guest just asks the
284 * Host to make the change anyway, because the Host controls the real IDT.
285 */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100286static void lguest_write_idt_entry(gate_desc *dt,
287 int entrynum, const gate_desc *g)
Rusty Russell07ad1572007-07-19 01:49:22 -0700288{
Rusty Russell2e04ef72009-07-30 16:03:45 -0600289 /*
290 * The gate_desc structure is 8 bytes long: we hand it to the Host in
Rusty Russella6bd8e12008-03-28 11:05:53 -0500291 * two 32-bit chunks. The whole 32-bit kernel used to hand descriptors
292 * around like this; typesafety wasn't a big concern in Linux's early
Rusty Russell2e04ef72009-07-30 16:03:45 -0600293 * years.
294 */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100295 u32 *desc = (u32 *)g;
Rusty Russellb2b47c22007-07-26 10:41:02 -0700296 /* Keep the local copy up to date. */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100297 native_write_idt_entry(dt, entrynum, g);
Rusty Russellb2b47c22007-07-26 10:41:02 -0700298 /* Tell Host about this new entry. */
Rusty Russell091ebf02010-04-14 21:43:54 -0600299 hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1], 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700300}
301
Rusty Russell2e04ef72009-07-30 16:03:45 -0600302/*
303 * Changing to a different IDT is very rare: we keep the IDT up-to-date every
Rusty Russellb2b47c22007-07-26 10:41:02 -0700304 * time it is written, so we can simply loop through all entries and tell the
Rusty Russell2e04ef72009-07-30 16:03:45 -0600305 * Host about them.
306 */
Glauber de Oliveira Costa6b68f012008-01-30 13:31:12 +0100307static void lguest_load_idt(const struct desc_ptr *desc)
Rusty Russell07ad1572007-07-19 01:49:22 -0700308{
309 unsigned int i;
310 struct desc_struct *idt = (void *)desc->address;
311
312 for (i = 0; i < (desc->size+1)/8; i++)
Rusty Russell091ebf02010-04-14 21:43:54 -0600313 hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700314}
315
Rusty Russellb2b47c22007-07-26 10:41:02 -0700316/*
317 * The Global Descriptor Table.
318 *
319 * The Intel architecture defines another table, called the Global Descriptor
320 * Table (GDT). You tell the CPU where it is (and its size) using the "lgdt"
321 * instruction, and then several other instructions refer to entries in the
322 * table. There are three entries which the Switcher needs, so the Host simply
323 * controls the entire thing and the Guest asks it to make changes using the
324 * LOAD_GDT hypercall.
325 *
Rusty Russella489f0b2009-04-19 23:14:00 -0600326 * This is the exactly like the IDT code.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700327 */
Glauber de Oliveira Costa6b68f012008-01-30 13:31:12 +0100328static void lguest_load_gdt(const struct desc_ptr *desc)
Rusty Russell07ad1572007-07-19 01:49:22 -0700329{
Rusty Russella489f0b2009-04-19 23:14:00 -0600330 unsigned int i;
331 struct desc_struct *gdt = (void *)desc->address;
332
333 for (i = 0; i < (desc->size+1)/8; i++)
Rusty Russell091ebf02010-04-14 21:43:54 -0600334 hcall(LHCALL_LOAD_GDT_ENTRY, i, gdt[i].a, gdt[i].b, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700335}
336
Rusty Russell2e04ef72009-07-30 16:03:45 -0600337/*
Rusty Russell9b6efcd2010-09-21 10:54:01 -0600338 * For a single GDT entry which changes, we simply change our copy and
339 * then tell the host about it.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600340 */
Glauber de Oliveira Costa014b15b2008-01-30 13:31:13 +0100341static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
342 const void *desc, int type)
Rusty Russell07ad1572007-07-19 01:49:22 -0700343{
Glauber de Oliveira Costa014b15b2008-01-30 13:31:13 +0100344 native_write_gdt_entry(dt, entrynum, desc, type);
Rusty Russella489f0b2009-04-19 23:14:00 -0600345 /* Tell Host about this new entry. */
Rusty Russell091ebf02010-04-14 21:43:54 -0600346 hcall(LHCALL_LOAD_GDT_ENTRY, entrynum,
347 dt[entrynum].a, dt[entrynum].b, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700348}
349
Rusty Russell2e04ef72009-07-30 16:03:45 -0600350/*
Rusty Russell9b6efcd2010-09-21 10:54:01 -0600351 * There are three "thread local storage" GDT entries which change
Rusty Russellb2b47c22007-07-26 10:41:02 -0700352 * on every context switch (these three entries are how glibc implements
Rusty Russell9b6efcd2010-09-21 10:54:01 -0600353 * __thread variables). As an optimization, we have a hypercall
354 * specifically for this case.
355 *
356 * Wouldn't it be nicer to have a general LOAD_GDT_ENTRIES hypercall
357 * which took a range of entries?
Rusty Russell2e04ef72009-07-30 16:03:45 -0600358 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700359static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
360{
Rusty Russell2e04ef72009-07-30 16:03:45 -0600361 /*
362 * There's one problem which normal hardware doesn't have: the Host
Rusty Russell0d027c02007-08-09 20:57:13 +1000363 * can't handle us removing entries we're currently using. So we clear
Rusty Russell2e04ef72009-07-30 16:03:45 -0600364 * the GS register here: if it's needed it'll be reloaded anyway.
365 */
Tejun Heoccbeed32009-02-09 22:17:40 +0900366 lazy_load_gs(0);
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200367 lazy_hcall2(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu);
Rusty Russell07ad1572007-07-19 01:49:22 -0700368}
369
Rusty Russell2e04ef72009-07-30 16:03:45 -0600370/*G:038
371 * That's enough excitement for now, back to ploughing through each of the
372 * different pv_ops structures (we're about 1/3 of the way through).
Rusty Russellb2b47c22007-07-26 10:41:02 -0700373 *
374 * This is the Local Descriptor Table, another weird Intel thingy. Linux only
375 * uses this for some strange applications like Wine. We don't do anything
Rusty Russell2e04ef72009-07-30 16:03:45 -0600376 * here, so they'll get an informative and friendly Segmentation Fault.
377 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700378static void lguest_set_ldt(const void *addr, unsigned entries)
379{
380}
381
Rusty Russell2e04ef72009-07-30 16:03:45 -0600382/*
383 * This loads a GDT entry into the "Task Register": that entry points to a
Rusty Russellb2b47c22007-07-26 10:41:02 -0700384 * structure called the Task State Segment. Some comments scattered though the
385 * kernel code indicate that this used for task switching in ages past, along
386 * with blood sacrifice and astrology.
387 *
388 * Now there's nothing interesting in here that we don't get told elsewhere.
389 * But the native version uses the "ltr" instruction, which makes the Host
390 * complain to the Guest about a Segmentation Fault and it'll oops. So we
Rusty Russell2e04ef72009-07-30 16:03:45 -0600391 * override the native version with a do-nothing version.
392 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700393static void lguest_load_tr_desc(void)
394{
395}
396
Rusty Russell2e04ef72009-07-30 16:03:45 -0600397/*
398 * The "cpuid" instruction is a way of querying both the CPU identity
Rusty Russellb2b47c22007-07-26 10:41:02 -0700399 * (manufacturer, model, etc) and its features. It was introduced before the
Rusty Russella6bd8e12008-03-28 11:05:53 -0500400 * Pentium in 1993 and keeps getting extended by both Intel, AMD and others.
401 * As you might imagine, after a decade and a half this treatment, it is now a
402 * giant ball of hair. Its entry in the current Intel manual runs to 28 pages.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700403 *
404 * This instruction even it has its own Wikipedia entry. The Wikipedia entry
Adrian Knoth8d431f42011-07-11 18:08:47 +0200405 * has been translated into 6 languages. I am not making this up!
Rusty Russellb2b47c22007-07-26 10:41:02 -0700406 *
407 * We could get funky here and identify ourselves as "GenuineLguest", but
408 * instead we just use the real "cpuid" instruction. Then I pretty much turned
409 * off feature bits until the Guest booted. (Don't say that: you'll damage
410 * lguest sales!) Shut up, inner voice! (Hey, just pointing out that this is
Lucas De Marchi0d2eb442011-03-17 16:24:16 -0300411 * hardly future proof.) No one's listening! They don't like you anyway,
Rusty Russellb2b47c22007-07-26 10:41:02 -0700412 * parenthetic weirdo!
413 *
414 * Replacing the cpuid so we can turn features off is great for the kernel, but
415 * anyone (including userspace) can just use the raw "cpuid" instruction and
416 * the Host won't even notice since it isn't privileged. So we try not to get
Rusty Russell2e04ef72009-07-30 16:03:45 -0600417 * too worked up about it.
418 */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100419static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
420 unsigned int *cx, unsigned int *dx)
Rusty Russell07ad1572007-07-19 01:49:22 -0700421{
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100422 int function = *ax;
Rusty Russell07ad1572007-07-19 01:49:22 -0700423
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100424 native_cpuid(ax, bx, cx, dx);
Rusty Russell07ad1572007-07-19 01:49:22 -0700425 switch (function) {
Rusty Russell2e04ef72009-07-30 16:03:45 -0600426 /*
427 * CPUID 0 gives the highest legal CPUID number (and the ID string).
428 * We futureproof our code a little by sticking to known CPUID values.
429 */
430 case 0:
Rusty Russell7a504922009-07-17 21:47:44 -0600431 if (*ax > 5)
432 *ax = 5;
433 break;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600434
435 /*
436 * CPUID 1 is a basic feature request.
437 *
438 * CX: we only allow kernel to see SSE3, CMPXCHG16B and SSSE3
439 * DX: SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU and PAE.
440 */
441 case 1:
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100442 *cx &= 0x00002201;
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600443 *dx &= 0x07808151;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600444 /*
445 * The Host can do a nice optimization if it knows that the
Rusty Russellb2b47c22007-07-26 10:41:02 -0700446 * kernel mappings (addresses above 0xC0000000 or whatever
447 * PAGE_OFFSET is set to) haven't changed. But Linux calls
448 * flush_tlb_user() for both user and kernel mappings unless
Rusty Russell2e04ef72009-07-30 16:03:45 -0600449 * the Page Global Enable (PGE) feature bit is set.
450 */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100451 *dx |= 0x00002000;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600452 /*
453 * We also lie, and say we're family id 5. 6 or greater
Rusty Russellcbd88c82009-03-09 10:06:22 -0600454 * leads to a rdmsr in early_init_intel which we can't handle.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600455 * Family ID is returned as bits 8-12 in ax.
456 */
Rusty Russellcbd88c82009-03-09 10:06:22 -0600457 *ax &= 0xFFFFF0FF;
458 *ax |= 0x00000500;
Rusty Russell07ad1572007-07-19 01:49:22 -0700459 break;
Rusty Russell89cfc992011-10-27 10:56:17 +1030460
461 /*
462 * This is used to detect if we're running under KVM. We might be,
463 * but that's a Host matter, not us. So say we're not.
464 */
465 case KVM_CPUID_SIGNATURE:
466 *bx = *cx = *dx = 0;
467 break;
468
Rusty Russell2e04ef72009-07-30 16:03:45 -0600469 /*
470 * 0x80000000 returns the highest Extended Function, so we futureproof
471 * like we do above by limiting it to known fields.
472 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700473 case 0x80000000:
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100474 if (*ax > 0x80000008)
475 *ax = 0x80000008;
Rusty Russell07ad1572007-07-19 01:49:22 -0700476 break;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600477
478 /*
479 * PAE systems can mark pages as non-executable. Linux calls this the
480 * NX bit. Intel calls it XD (eXecute Disable), AMD EVP (Enhanced
Adrian Knoth64be1152011-07-11 18:07:14 +0200481 * Virus Protection). We just switch it off here, since we don't
Rusty Russell2e04ef72009-07-30 16:03:45 -0600482 * support it.
483 */
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600484 case 0x80000001:
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600485 *dx &= ~(1 << 20);
486 break;
Rusty Russell07ad1572007-07-19 01:49:22 -0700487 }
488}
489
Rusty Russell2e04ef72009-07-30 16:03:45 -0600490/*
491 * Intel has four control registers, imaginatively named cr0, cr2, cr3 and cr4.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700492 * I assume there's a cr1, but it hasn't bothered us yet, so we'll not bother
493 * it. The Host needs to know when the Guest wants to change them, so we have
494 * a whole series of functions like read_cr0() and write_cr0().
495 *
Rusty Russelle1e72962007-10-25 15:02:50 +1000496 * We start with cr0. cr0 allows you to turn on and off all kinds of basic
Rusty Russellb2b47c22007-07-26 10:41:02 -0700497 * features, but Linux only really cares about one: the horrifically-named Task
498 * Switched (TS) bit at bit 3 (ie. 8)
499 *
500 * What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if
501 * the floating point unit is used. Which allows us to restore FPU state
502 * lazily after a task switch, and Linux uses that gratefully, but wouldn't a
503 * name like "FPUTRAP bit" be a little less cryptic?
504 *
Rusty Russellad5173f2008-10-31 11:24:27 -0500505 * We store cr0 locally because the Host never changes it. The Guest sometimes
Rusty Russell2e04ef72009-07-30 16:03:45 -0600506 * wants to read it and we'd prefer not to bother the Host unnecessarily.
507 */
Rusty Russellad5173f2008-10-31 11:24:27 -0500508static unsigned long current_cr0;
Rusty Russell07ad1572007-07-19 01:49:22 -0700509static void lguest_write_cr0(unsigned long val)
510{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200511 lazy_hcall1(LHCALL_TS, val & X86_CR0_TS);
Rusty Russell07ad1572007-07-19 01:49:22 -0700512 current_cr0 = val;
513}
514
515static unsigned long lguest_read_cr0(void)
516{
517 return current_cr0;
518}
519
Rusty Russell2e04ef72009-07-30 16:03:45 -0600520/*
521 * Intel provided a special instruction to clear the TS bit for people too cool
Rusty Russellb2b47c22007-07-26 10:41:02 -0700522 * to use write_cr0() to do it. This "clts" instruction is faster, because all
Rusty Russell2e04ef72009-07-30 16:03:45 -0600523 * the vowels have been optimized out.
524 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700525static void lguest_clts(void)
526{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200527 lazy_hcall1(LHCALL_TS, 0);
Rusty Russell25c47bb2007-10-25 14:09:53 +1000528 current_cr0 &= ~X86_CR0_TS;
Rusty Russell07ad1572007-07-19 01:49:22 -0700529}
530
Rusty Russell2e04ef72009-07-30 16:03:45 -0600531/*
532 * cr2 is the virtual address of the last page fault, which the Guest only ever
Rusty Russellb2b47c22007-07-26 10:41:02 -0700533 * reads. The Host kindly writes this into our "struct lguest_data", so we
Rusty Russell2e04ef72009-07-30 16:03:45 -0600534 * just read it out of there.
535 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700536static unsigned long lguest_read_cr2(void)
537{
538 return lguest_data.cr2;
539}
540
Rusty Russellad5173f2008-10-31 11:24:27 -0500541/* See lguest_set_pte() below. */
542static bool cr3_changed = false;
Rusty Russell5dea1c82011-07-22 14:39:48 +0930543static unsigned long current_cr3;
Rusty Russellad5173f2008-10-31 11:24:27 -0500544
Rusty Russell2e04ef72009-07-30 16:03:45 -0600545/*
546 * cr3 is the current toplevel pagetable page: the principle is the same as
Rusty Russell5dea1c82011-07-22 14:39:48 +0930547 * cr0. Keep a local copy, and tell the Host when it changes.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600548 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700549static void lguest_write_cr3(unsigned long cr3)
550{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200551 lazy_hcall1(LHCALL_NEW_PGTABLE, cr3);
Rusty Russell5dea1c82011-07-22 14:39:48 +0930552 current_cr3 = cr3;
Rusty Russellbb4093d2010-12-16 17:03:15 -0600553
554 /* These two page tables are simple, linear, and used during boot */
555 if (cr3 != __pa(swapper_pg_dir) && cr3 != __pa(initial_page_table))
556 cr3_changed = true;
Rusty Russell07ad1572007-07-19 01:49:22 -0700557}
558
559static unsigned long lguest_read_cr3(void)
560{
Rusty Russell5dea1c82011-07-22 14:39:48 +0930561 return current_cr3;
Rusty Russell07ad1572007-07-19 01:49:22 -0700562}
563
Rusty Russelle1e72962007-10-25 15:02:50 +1000564/* cr4 is used to enable and disable PGE, but we don't care. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700565static unsigned long lguest_read_cr4(void)
566{
567 return 0;
568}
569
570static void lguest_write_cr4(unsigned long val)
571{
572}
573
Rusty Russellb2b47c22007-07-26 10:41:02 -0700574/*
575 * Page Table Handling.
576 *
577 * Now would be a good time to take a rest and grab a coffee or similarly
578 * relaxing stimulant. The easy parts are behind us, and the trek gradually
579 * winds uphill from here.
580 *
581 * Quick refresher: memory is divided into "pages" of 4096 bytes each. The CPU
582 * maps virtual addresses to physical addresses using "page tables". We could
583 * use one huge index of 1 million entries: each address is 4 bytes, so that's
584 * 1024 pages just to hold the page tables. But since most virtual addresses
Rusty Russelle1e72962007-10-25 15:02:50 +1000585 * are unused, we use a two level index which saves space. The cr3 register
Rusty Russellb2b47c22007-07-26 10:41:02 -0700586 * contains the physical address of the top level "page directory" page, which
587 * contains physical addresses of up to 1024 second-level pages. Each of these
588 * second level pages contains up to 1024 physical addresses of actual pages,
589 * or Page Table Entries (PTEs).
590 *
591 * Here's a diagram, where arrows indicate physical addresses:
592 *
Rusty Russelle1e72962007-10-25 15:02:50 +1000593 * cr3 ---> +---------+
Rusty Russellb2b47c22007-07-26 10:41:02 -0700594 * | --------->+---------+
595 * | | | PADDR1 |
Rusty Russella91d74a2009-07-30 16:03:45 -0600596 * Mid-level | | PADDR2 |
Rusty Russellb2b47c22007-07-26 10:41:02 -0700597 * (PMD) page | | |
598 * | | Lower-level |
599 * | | (PTE) page |
600 * | | | |
601 * .... ....
602 *
603 * So to convert a virtual address to a physical address, we look up the top
604 * level, which points us to the second level, which gives us the physical
605 * address of that page. If the top level entry was not present, or the second
606 * level entry was not present, then the virtual address is invalid (we
607 * say "the page was not mapped").
608 *
609 * Put another way, a 32-bit virtual address is divided up like so:
610 *
611 * 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
612 * |<---- 10 bits ---->|<---- 10 bits ---->|<------ 12 bits ------>|
613 * Index into top Index into second Offset within page
614 * page directory page pagetable page
615 *
Rusty Russella91d74a2009-07-30 16:03:45 -0600616 * Now, unfortunately, this isn't the whole story: Intel added Physical Address
617 * Extension (PAE) to allow 32 bit systems to use 64GB of memory (ie. 36 bits).
618 * These are held in 64-bit page table entries, so we can now only fit 512
619 * entries in a page, and the neat three-level tree breaks down.
620 *
621 * The result is a four level page table:
622 *
623 * cr3 --> [ 4 Upper ]
624 * [ Level ]
625 * [ Entries ]
626 * [(PUD Page)]---> +---------+
627 * | --------->+---------+
628 * | | | PADDR1 |
629 * Mid-level | | PADDR2 |
630 * (PMD) page | | |
631 * | | Lower-level |
632 * | | (PTE) page |
633 * | | | |
634 * .... ....
635 *
636 *
637 * And the virtual address is decoded as:
638 *
639 * 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
640 * |<-2->|<--- 9 bits ---->|<---- 9 bits --->|<------ 12 bits ------>|
641 * Index into Index into mid Index into lower Offset within page
642 * top entries directory page pagetable page
643 *
644 * It's too hard to switch between these two formats at runtime, so Linux only
645 * supports one or the other depending on whether CONFIG_X86_PAE is set. Many
646 * distributions turn it on, and not just for people with silly amounts of
647 * memory: the larger PTE entries allow room for the NX bit, which lets the
648 * kernel disable execution of pages and increase security.
649 *
650 * This was a problem for lguest, which couldn't run on these distributions;
651 * then Matias Zabaljauregui figured it all out and implemented it, and only a
652 * handful of puppies were crushed in the process!
653 *
654 * Back to our point: the kernel spends a lot of time changing both the
655 * top-level page directory and lower-level pagetable pages. The Guest doesn't
656 * know physical addresses, so while it maintains these page tables exactly
657 * like normal, it also needs to keep the Host informed whenever it makes a
658 * change: the Host will create the real page tables based on the Guests'.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700659 */
660
Rusty Russell2e04ef72009-07-30 16:03:45 -0600661/*
Rusty Russella91d74a2009-07-30 16:03:45 -0600662 * The Guest calls this after it has set a second-level entry (pte), ie. to map
Rusty Russell9f542882011-07-22 14:39:50 +0930663 * a page into a process' address space. We tell the Host the toplevel and
Rusty Russella91d74a2009-07-30 16:03:45 -0600664 * address this corresponds to. The Guest uses one pagetable per process, so
665 * we need to tell the Host which one we're changing (mm->pgd).
Rusty Russell2e04ef72009-07-30 16:03:45 -0600666 */
Rusty Russellb7ff99e2009-03-30 21:55:23 -0600667static void lguest_pte_update(struct mm_struct *mm, unsigned long addr,
668 pte_t *ptep)
669{
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600670#ifdef CONFIG_X86_PAE
Rusty Russella91d74a2009-07-30 16:03:45 -0600671 /* PAE needs to hand a 64 bit page table entry, so it uses two args. */
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600672 lazy_hcall4(LHCALL_SET_PTE, __pa(mm->pgd), addr,
673 ptep->pte_low, ptep->pte_high);
674#else
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200675 lazy_hcall3(LHCALL_SET_PTE, __pa(mm->pgd), addr, ptep->pte_low);
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600676#endif
Rusty Russellb7ff99e2009-03-30 21:55:23 -0600677}
678
Rusty Russella91d74a2009-07-30 16:03:45 -0600679/* This is the "set and update" combo-meal-deal version. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700680static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
681 pte_t *ptep, pte_t pteval)
682{
Matias Zabaljauregui90603d12009-06-12 22:27:06 -0600683 native_set_pte(ptep, pteval);
Rusty Russellb7ff99e2009-03-30 21:55:23 -0600684 lguest_pte_update(mm, addr, ptep);
Rusty Russell07ad1572007-07-19 01:49:22 -0700685}
686
Rusty Russell2e04ef72009-07-30 16:03:45 -0600687/*
688 * The Guest calls lguest_set_pud to set a top-level entry and lguest_set_pmd
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600689 * to set a middle-level entry when PAE is activated.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600690 *
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600691 * Again, we set the entry then tell the Host which page we changed,
Rusty Russell2e04ef72009-07-30 16:03:45 -0600692 * and the index of the entry we changed.
693 */
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600694#ifdef CONFIG_X86_PAE
695static void lguest_set_pud(pud_t *pudp, pud_t pudval)
696{
697 native_set_pud(pudp, pudval);
698
699 /* 32 bytes aligned pdpt address and the index. */
700 lazy_hcall2(LHCALL_SET_PGD, __pa(pudp) & 0xFFFFFFE0,
701 (__pa(pudp) & 0x1F) / sizeof(pud_t));
702}
703
704static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
705{
706 native_set_pmd(pmdp, pmdval);
707 lazy_hcall2(LHCALL_SET_PMD, __pa(pmdp) & PAGE_MASK,
708 (__pa(pmdp) & (PAGE_SIZE - 1)) / sizeof(pmd_t));
709}
710#else
711
Rusty Russell2e04ef72009-07-30 16:03:45 -0600712/* The Guest calls lguest_set_pmd to set a top-level entry when !PAE. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700713static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
714{
Matias Zabaljauregui90603d12009-06-12 22:27:06 -0600715 native_set_pmd(pmdp, pmdval);
Matias Zabaljaureguiebe0ba82009-05-30 15:48:08 -0300716 lazy_hcall2(LHCALL_SET_PGD, __pa(pmdp) & PAGE_MASK,
Matias Zabaljauregui90603d12009-06-12 22:27:06 -0600717 (__pa(pmdp) & (PAGE_SIZE - 1)) / sizeof(pmd_t));
Rusty Russell07ad1572007-07-19 01:49:22 -0700718}
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600719#endif
Rusty Russell07ad1572007-07-19 01:49:22 -0700720
Rusty Russell2e04ef72009-07-30 16:03:45 -0600721/*
722 * There are a couple of legacy places where the kernel sets a PTE, but we
Rusty Russellb2b47c22007-07-26 10:41:02 -0700723 * don't know the top level any more. This is useless for us, since we don't
724 * know which pagetable is changing or what address, so we just tell the Host
725 * to forget all of them. Fortunately, this is very rare.
726 *
727 * ... except in early boot when the kernel sets up the initial pagetables,
Rusty Russellbb4093d2010-12-16 17:03:15 -0600728 * which makes booting astonishingly slow: 48 seconds! So we don't even tell
729 * the Host anything changed until we've done the first real page table switch,
730 * which brings boot back to 4.3 seconds.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600731 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700732static void lguest_set_pte(pte_t *ptep, pte_t pteval)
733{
Matias Zabaljauregui90603d12009-06-12 22:27:06 -0600734 native_set_pte(ptep, pteval);
Rusty Russellad5173f2008-10-31 11:24:27 -0500735 if (cr3_changed)
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200736 lazy_hcall1(LHCALL_FLUSH_TLB, 1);
Rusty Russell07ad1572007-07-19 01:49:22 -0700737}
738
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600739#ifdef CONFIG_X86_PAE
Rusty Russella91d74a2009-07-30 16:03:45 -0600740/*
741 * With 64-bit PTE values, we need to be careful setting them: if we set 32
742 * bits at a time, the hardware could see a weird half-set entry. These
743 * versions ensure we update all 64 bits at once.
744 */
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600745static void lguest_set_pte_atomic(pte_t *ptep, pte_t pte)
746{
747 native_set_pte_atomic(ptep, pte);
748 if (cr3_changed)
749 lazy_hcall1(LHCALL_FLUSH_TLB, 1);
750}
751
Rusty Russella91d74a2009-07-30 16:03:45 -0600752static void lguest_pte_clear(struct mm_struct *mm, unsigned long addr,
753 pte_t *ptep)
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600754{
755 native_pte_clear(mm, addr, ptep);
756 lguest_pte_update(mm, addr, ptep);
757}
758
Rusty Russella91d74a2009-07-30 16:03:45 -0600759static void lguest_pmd_clear(pmd_t *pmdp)
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -0600760{
761 lguest_set_pmd(pmdp, __pmd(0));
762}
763#endif
764
Rusty Russell2e04ef72009-07-30 16:03:45 -0600765/*
766 * Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
Rusty Russellb2b47c22007-07-26 10:41:02 -0700767 * native page table operations. On native hardware you can set a new page
768 * table entry whenever you want, but if you want to remove one you have to do
769 * a TLB flush (a TLB is a little cache of page table entries kept by the CPU).
770 *
771 * So the lguest_set_pte_at() and lguest_set_pmd() functions above are only
772 * called when a valid entry is written, not when it's removed (ie. marked not
773 * present). Instead, this is where we come when the Guest wants to remove a
774 * page table entry: we tell the Host to set that entry to 0 (ie. the present
Rusty Russell2e04ef72009-07-30 16:03:45 -0600775 * bit is zero).
776 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700777static void lguest_flush_tlb_single(unsigned long addr)
778{
Rusty Russellb2b47c22007-07-26 10:41:02 -0700779 /* Simply set it to zero: if it was not, it will fault back in. */
Rusty Russell5dea1c82011-07-22 14:39:48 +0930780 lazy_hcall3(LHCALL_SET_PTE, current_cr3, addr, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700781}
782
Rusty Russell2e04ef72009-07-30 16:03:45 -0600783/*
784 * This is what happens after the Guest has removed a large number of entries.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700785 * This tells the Host that any of the page table entries for userspace might
Rusty Russell2e04ef72009-07-30 16:03:45 -0600786 * have changed, ie. virtual addresses below PAGE_OFFSET.
787 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700788static void lguest_flush_tlb_user(void)
789{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200790 lazy_hcall1(LHCALL_FLUSH_TLB, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700791}
792
Rusty Russell2e04ef72009-07-30 16:03:45 -0600793/*
794 * This is called when the kernel page tables have changed. That's not very
Rusty Russellb2b47c22007-07-26 10:41:02 -0700795 * common (unless the Guest is using highmem, which makes the Guest extremely
Rusty Russell2e04ef72009-07-30 16:03:45 -0600796 * slow), so it's worth separating this from the user flushing above.
797 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700798static void lguest_flush_tlb_kernel(void)
799{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -0200800 lazy_hcall1(LHCALL_FLUSH_TLB, 1);
Rusty Russell07ad1572007-07-19 01:49:22 -0700801}
802
Rusty Russellb2b47c22007-07-26 10:41:02 -0700803/*
804 * The Unadvanced Programmable Interrupt Controller.
805 *
806 * This is an attempt to implement the simplest possible interrupt controller.
807 * I spent some time looking though routines like set_irq_chip_and_handler,
808 * set_irq_chip_and_handler_name, set_irq_chip_data and set_phasers_to_stun and
809 * I *think* this is as simple as it gets.
810 *
811 * We can tell the Host what interrupts we want blocked ready for using the
812 * lguest_data.interrupts bitmap, so disabling (aka "masking") them is as
813 * simple as setting a bit. We don't actually "ack" interrupts as such, we
814 * just mask and unmask them. I wonder if we should be cleverer?
815 */
Thomas Gleixnerfe25c7f2010-09-28 14:57:24 +0200816static void disable_lguest_irq(struct irq_data *data)
Rusty Russell07ad1572007-07-19 01:49:22 -0700817{
Thomas Gleixnerfe25c7f2010-09-28 14:57:24 +0200818 set_bit(data->irq, lguest_data.blocked_interrupts);
Rusty Russell07ad1572007-07-19 01:49:22 -0700819}
820
Thomas Gleixnerfe25c7f2010-09-28 14:57:24 +0200821static void enable_lguest_irq(struct irq_data *data)
Rusty Russell07ad1572007-07-19 01:49:22 -0700822{
Thomas Gleixnerfe25c7f2010-09-28 14:57:24 +0200823 clear_bit(data->irq, lguest_data.blocked_interrupts);
Rusty Russell07ad1572007-07-19 01:49:22 -0700824}
825
Rusty Russellb2b47c22007-07-26 10:41:02 -0700826/* This structure describes the lguest IRQ controller. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700827static struct irq_chip lguest_irq_controller = {
828 .name = "lguest",
Thomas Gleixnerfe25c7f2010-09-28 14:57:24 +0200829 .irq_mask = disable_lguest_irq,
830 .irq_mask_ack = disable_lguest_irq,
831 .irq_unmask = enable_lguest_irq,
Rusty Russell07ad1572007-07-19 01:49:22 -0700832};
833
Rusty Russell2e04ef72009-07-30 16:03:45 -0600834/*
835 * This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
Rusty Russellb2b47c22007-07-26 10:41:02 -0700836 * interrupt (except 128, which is used for system calls), and then tells the
837 * Linux infrastructure that each interrupt is controlled by our level-based
Rusty Russell2e04ef72009-07-30 16:03:45 -0600838 * lguest interrupt controller.
839 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700840static void __init lguest_init_IRQ(void)
841{
842 unsigned int i;
843
Rusty Russell10283752009-06-12 22:26:59 -0600844 for (i = FIRST_EXTERNAL_VECTOR; i < NR_VECTORS; i++) {
Rusty Russell2e04ef72009-07-30 16:03:45 -0600845 /* Some systems map "vectors" to interrupts weirdly. Not us! */
Rusty Russellced05dd2011-01-20 21:37:29 -0600846 __this_cpu_write(vector_irq[i], i - FIRST_EXTERNAL_VECTOR);
Rusty Russell10283752009-06-12 22:26:59 -0600847 if (i != SYSCALL_VECTOR)
848 set_intr_gate(i, interrupt[i - FIRST_EXTERNAL_VECTOR]);
Rusty Russell07ad1572007-07-19 01:49:22 -0700849 }
Rusty Russell2e04ef72009-07-30 16:03:45 -0600850
851 /*
852 * This call is required to set up for 4k stacks, where we have
853 * separate stacks for hard and soft interrupts.
854 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700855 irq_ctx_init(smp_processor_id());
856}
857
Rusty Russella91d74a2009-07-30 16:03:45 -0600858/*
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030859 * Interrupt descriptors are allocated as-needed, but low-numbered ones are
860 * reserved by the generic x86 code. So we ignore irq_alloc_desc_at if it
861 * tells us the irq is already used: other errors (ie. ENOMEM) we take
862 * seriously.
Rusty Russella91d74a2009-07-30 16:03:45 -0600863 */
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030864int lguest_setup_irq(unsigned int irq)
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600865{
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030866 int err;
867
868 /* Returns -ve error or vector number. */
869 err = irq_alloc_desc_at(irq, 0);
870 if (err < 0 && err != -EEXIST)
871 return err;
872
Thomas Gleixner2c778652011-03-12 12:20:43 +0100873 irq_set_chip_and_handler_name(irq, &lguest_irq_controller,
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600874 handle_level_irq, "level");
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030875 return 0;
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600876}
877
Rusty Russellb2b47c22007-07-26 10:41:02 -0700878/*
879 * Time.
880 *
881 * It would be far better for everyone if the Guest had its own clock, but
Rusty Russell6c8dca52007-07-27 13:42:52 +1000882 * until then the Host gives us the time on every interrupt.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700883 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700884static unsigned long lguest_get_wallclock(void)
885{
Rusty Russell6c8dca52007-07-27 13:42:52 +1000886 return lguest_data.time.tv_sec;
Rusty Russell07ad1572007-07-19 01:49:22 -0700887}
888
Rusty Russell2e04ef72009-07-30 16:03:45 -0600889/*
890 * The TSC is an Intel thing called the Time Stamp Counter. The Host tells us
Rusty Russella6bd8e12008-03-28 11:05:53 -0500891 * what speed it runs at, or 0 if it's unusable as a reliable clock source.
892 * This matches what we want here: if we return 0 from this function, the x86
Rusty Russell2e04ef72009-07-30 16:03:45 -0600893 * TSC clock will give up and not register itself.
894 */
Alok Katariae93ef942008-07-01 11:43:36 -0700895static unsigned long lguest_tsc_khz(void)
Rusty Russell3fabc552008-03-11 09:35:56 -0500896{
897 return lguest_data.tsc_khz;
898}
899
Rusty Russell2e04ef72009-07-30 16:03:45 -0600900/*
901 * If we can't use the TSC, the kernel falls back to our lower-priority
902 * "lguest_clock", where we read the time value given to us by the Host.
903 */
Magnus Damm8e196082009-04-21 12:24:00 -0700904static cycle_t lguest_clock_read(struct clocksource *cs)
Rusty Russell07ad1572007-07-19 01:49:22 -0700905{
Rusty Russell6c8dca52007-07-27 13:42:52 +1000906 unsigned long sec, nsec;
907
Rusty Russell2e04ef72009-07-30 16:03:45 -0600908 /*
909 * Since the time is in two parts (seconds and nanoseconds), we risk
Rusty Russell3fabc552008-03-11 09:35:56 -0500910 * reading it just as it's changing from 99 & 0.999999999 to 100 and 0,
911 * and getting 99 and 0. As Linux tends to come apart under the stress
Rusty Russell2e04ef72009-07-30 16:03:45 -0600912 * of time travel, we must be careful:
913 */
Rusty Russell6c8dca52007-07-27 13:42:52 +1000914 do {
915 /* First we read the seconds part. */
916 sec = lguest_data.time.tv_sec;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600917 /*
918 * This read memory barrier tells the compiler and the CPU that
Rusty Russell6c8dca52007-07-27 13:42:52 +1000919 * this can't be reordered: we have to complete the above
Rusty Russell2e04ef72009-07-30 16:03:45 -0600920 * before going on.
921 */
Rusty Russell6c8dca52007-07-27 13:42:52 +1000922 rmb();
923 /* Now we read the nanoseconds part. */
924 nsec = lguest_data.time.tv_nsec;
925 /* Make sure we've done that. */
926 rmb();
927 /* Now if the seconds part has changed, try again. */
928 } while (unlikely(lguest_data.time.tv_sec != sec));
929
Rusty Russell3fabc552008-03-11 09:35:56 -0500930 /* Our lguest clock is in real nanoseconds. */
Rusty Russell6c8dca52007-07-27 13:42:52 +1000931 return sec*1000000000ULL + nsec;
Rusty Russell07ad1572007-07-19 01:49:22 -0700932}
933
Rusty Russell3fabc552008-03-11 09:35:56 -0500934/* This is the fallback clocksource: lower priority than the TSC clocksource. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700935static struct clocksource lguest_clock = {
936 .name = "lguest",
Rusty Russell3fabc552008-03-11 09:35:56 -0500937 .rating = 200,
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700938 .read = lguest_clock_read,
Rusty Russell6c8dca52007-07-27 13:42:52 +1000939 .mask = CLOCKSOURCE_MASK(64),
Tony Breeds05aa0262007-10-22 10:56:25 +1000940 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700941};
942
Rusty Russell2e04ef72009-07-30 16:03:45 -0600943/*
944 * We also need a "struct clock_event_device": Linux asks us to set it to go
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700945 * off some time in the future. Actually, James Morris figured all this out, I
Rusty Russell2e04ef72009-07-30 16:03:45 -0600946 * just applied the patch.
947 */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700948static int lguest_clockevent_set_next_event(unsigned long delta,
949 struct clock_event_device *evt)
950{
Rusty Russella6bd8e12008-03-28 11:05:53 -0500951 /* FIXME: I don't think this can ever happen, but James tells me he had
952 * to put this code in. Maybe we should remove it now. Anyone? */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700953 if (delta < LG_CLOCK_MIN_DELTA) {
954 if (printk_ratelimit())
955 printk(KERN_DEBUG "%s: small delta %lu ns\n",
Harvey Harrison77bf90e2008-03-03 11:37:23 -0800956 __func__, delta);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700957 return -ETIME;
958 }
Rusty Russella6bd8e12008-03-28 11:05:53 -0500959
960 /* Please wake us this far in the future. */
Rusty Russell091ebf02010-04-14 21:43:54 -0600961 hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0, 0);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700962 return 0;
963}
964
965static void lguest_clockevent_set_mode(enum clock_event_mode mode,
966 struct clock_event_device *evt)
967{
968 switch (mode) {
969 case CLOCK_EVT_MODE_UNUSED:
970 case CLOCK_EVT_MODE_SHUTDOWN:
971 /* A 0 argument shuts the clock down. */
Rusty Russell091ebf02010-04-14 21:43:54 -0600972 hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0, 0);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700973 break;
974 case CLOCK_EVT_MODE_ONESHOT:
975 /* This is what we expect. */
976 break;
977 case CLOCK_EVT_MODE_PERIODIC:
978 BUG();
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700979 case CLOCK_EVT_MODE_RESUME:
980 break;
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700981 }
982}
983
984/* This describes our primitive timer chip. */
985static struct clock_event_device lguest_clockevent = {
986 .name = "lguest",
987 .features = CLOCK_EVT_FEAT_ONESHOT,
988 .set_next_event = lguest_clockevent_set_next_event,
989 .set_mode = lguest_clockevent_set_mode,
990 .rating = INT_MAX,
991 .mult = 1,
992 .shift = 0,
993 .min_delta_ns = LG_CLOCK_MIN_DELTA,
994 .max_delta_ns = LG_CLOCK_MAX_DELTA,
995};
996
Rusty Russell2e04ef72009-07-30 16:03:45 -0600997/*
998 * This is the Guest timer interrupt handler (hardware interrupt 0). We just
999 * call the clockevent infrastructure and it does whatever needs doing.
1000 */
Rusty Russelld7e28ff2007-07-19 01:49:23 -07001001static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
1002{
1003 unsigned long flags;
1004
1005 /* Don't interrupt us while this is running. */
1006 local_irq_save(flags);
1007 lguest_clockevent.event_handler(&lguest_clockevent);
1008 local_irq_restore(flags);
1009}
1010
Rusty Russell2e04ef72009-07-30 16:03:45 -06001011/*
1012 * At some point in the boot process, we get asked to set up our timing
Rusty Russellb2b47c22007-07-26 10:41:02 -07001013 * infrastructure. The kernel doesn't expect timer interrupts before this, but
1014 * we cleverly initialized the "blocked_interrupts" field of "struct
Rusty Russell2e04ef72009-07-30 16:03:45 -06001015 * lguest_data" so that timer interrupts were blocked until now.
1016 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001017static void lguest_time_init(void)
1018{
Rusty Russellb2b47c22007-07-26 10:41:02 -07001019 /* Set up the timer interrupt (0) to go to our simple timer routine */
Rusty Russell15517f72011-05-30 11:14:08 -06001020 lguest_setup_irq(0);
Thomas Gleixner2c778652011-03-12 12:20:43 +01001021 irq_set_handler(0, lguest_time_irq);
Rusty Russell07ad1572007-07-19 01:49:22 -07001022
John Stultzb01cc1b2010-04-26 19:03:05 -07001023 clocksource_register_hz(&lguest_clock, NSEC_PER_SEC);
Rusty Russelld7e28ff2007-07-19 01:49:23 -07001024
Rusty Russellb2b47c22007-07-26 10:41:02 -07001025 /* We can't set cpumask in the initializer: damn C limitations! Set it
1026 * here and register our timer device. */
Rusty Russell320ab2b2008-12-13 21:20:26 +10301027 lguest_clockevent.cpumask = cpumask_of(0);
Rusty Russelld7e28ff2007-07-19 01:49:23 -07001028 clockevents_register_device(&lguest_clockevent);
1029
Rusty Russellb2b47c22007-07-26 10:41:02 -07001030 /* Finally, we unblock the timer interrupt. */
Rusty Russellbb6f1d92010-12-16 17:03:13 -06001031 clear_bit(0, lguest_data.blocked_interrupts);
Rusty Russell07ad1572007-07-19 01:49:22 -07001032}
1033
Rusty Russellb2b47c22007-07-26 10:41:02 -07001034/*
1035 * Miscellaneous bits and pieces.
1036 *
1037 * Here is an oddball collection of functions which the Guest needs for things
1038 * to work. They're pretty simple.
1039 */
1040
Rusty Russell2e04ef72009-07-30 16:03:45 -06001041/*
1042 * The Guest needs to tell the Host what stack it expects traps to use. For
Rusty Russellb2b47c22007-07-26 10:41:02 -07001043 * native hardware, this is part of the Task State Segment mentioned above in
1044 * lguest_load_tr_desc(), but to help hypervisors there's this special call.
1045 *
1046 * We tell the Host the segment we want to use (__KERNEL_DS is the kernel data
1047 * segment), the privilege level (we're privilege level 1, the Host is 0 and
1048 * will not tolerate us trying to use that), the stack pointer, and the number
Rusty Russell2e04ef72009-07-30 16:03:45 -06001049 * of pages in the stack.
1050 */
H. Peter Anvinfaca6222008-01-30 13:31:02 +01001051static void lguest_load_sp0(struct tss_struct *tss,
Rusty Russella6bd8e12008-03-28 11:05:53 -05001052 struct thread_struct *thread)
Rusty Russell07ad1572007-07-19 01:49:22 -07001053{
Matias Zabaljauregui4cd8b5e2009-03-14 13:37:52 -02001054 lazy_hcall3(LHCALL_SET_STACK, __KERNEL_DS | 0x1, thread->sp0,
1055 THREAD_SIZE / PAGE_SIZE);
Rusty Russell07ad1572007-07-19 01:49:22 -07001056}
1057
Rusty Russellb2b47c22007-07-26 10:41:02 -07001058/* Let's just say, I wouldn't do debugging under a Guest. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001059static void lguest_set_debugreg(int regno, unsigned long value)
1060{
1061 /* FIXME: Implement */
1062}
1063
Rusty Russell2e04ef72009-07-30 16:03:45 -06001064/*
1065 * There are times when the kernel wants to make sure that no memory writes are
Rusty Russellb2b47c22007-07-26 10:41:02 -07001066 * caught in the cache (that they've all reached real hardware devices). This
1067 * doesn't matter for the Guest which has virtual hardware.
1068 *
1069 * On the Pentium 4 and above, cpuid() indicates that the Cache Line Flush
1070 * (clflush) instruction is available and the kernel uses that. Otherwise, it
1071 * uses the older "Write Back and Invalidate Cache" (wbinvd) instruction.
1072 * Unlike clflush, wbinvd can only be run at privilege level 0. So we can
1073 * ignore clflush, but replace wbinvd.
1074 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001075static void lguest_wbinvd(void)
1076{
1077}
1078
Rusty Russell2e04ef72009-07-30 16:03:45 -06001079/*
1080 * If the Guest expects to have an Advanced Programmable Interrupt Controller,
Rusty Russellb2b47c22007-07-26 10:41:02 -07001081 * we play dumb by ignoring writes and returning 0 for reads. So it's no
1082 * longer Programmable nor Controlling anything, and I don't think 8 lines of
1083 * code qualifies for Advanced. It will also never interrupt anything. It
Rusty Russell2e04ef72009-07-30 16:03:45 -06001084 * does, however, allow us to get through the Linux boot code.
1085 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001086#ifdef CONFIG_X86_LOCAL_APIC
Suresh Siddhaad66dd32008-07-11 13:11:56 -07001087static void lguest_apic_write(u32 reg, u32 v)
Rusty Russell07ad1572007-07-19 01:49:22 -07001088{
1089}
1090
Suresh Siddhaad66dd32008-07-11 13:11:56 -07001091static u32 lguest_apic_read(u32 reg)
Rusty Russell07ad1572007-07-19 01:49:22 -07001092{
1093 return 0;
1094}
Suresh Siddha511d9d32008-07-14 09:49:14 -07001095
1096static u64 lguest_apic_icr_read(void)
1097{
1098 return 0;
1099}
1100
1101static void lguest_apic_icr_write(u32 low, u32 id)
1102{
1103 /* Warn to see if there's any stray references */
1104 WARN_ON(1);
1105}
1106
1107static void lguest_apic_wait_icr_idle(void)
1108{
1109 return;
1110}
1111
1112static u32 lguest_apic_safe_wait_icr_idle(void)
1113{
1114 return 0;
1115}
1116
Yinghai Luc1eeb2d2009-02-16 23:02:14 -08001117static void set_lguest_basic_apic_ops(void)
1118{
1119 apic->read = lguest_apic_read;
1120 apic->write = lguest_apic_write;
1121 apic->icr_read = lguest_apic_icr_read;
1122 apic->icr_write = lguest_apic_icr_write;
1123 apic->wait_icr_idle = lguest_apic_wait_icr_idle;
1124 apic->safe_wait_icr_idle = lguest_apic_safe_wait_icr_idle;
Suresh Siddha511d9d32008-07-14 09:49:14 -07001125};
Rusty Russell07ad1572007-07-19 01:49:22 -07001126#endif
1127
Rusty Russellb2b47c22007-07-26 10:41:02 -07001128/* STOP! Until an interrupt comes in. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001129static void lguest_safe_halt(void)
1130{
Rusty Russell091ebf02010-04-14 21:43:54 -06001131 hcall(LHCALL_HALT, 0, 0, 0, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -07001132}
1133
Rusty Russell2e04ef72009-07-30 16:03:45 -06001134/*
1135 * The SHUTDOWN hypercall takes a string to describe what's happening, and
Rusty Russella6bd8e12008-03-28 11:05:53 -05001136 * an argument which says whether this to restart (reboot) the Guest or not.
Rusty Russellb2b47c22007-07-26 10:41:02 -07001137 *
1138 * Note that the Host always prefers that the Guest speak in physical addresses
Rusty Russell2e04ef72009-07-30 16:03:45 -06001139 * rather than virtual addresses, so we use __pa() here.
1140 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001141static void lguest_power_off(void)
1142{
Rusty Russell091ebf02010-04-14 21:43:54 -06001143 hcall(LHCALL_SHUTDOWN, __pa("Power down"),
1144 LGUEST_SHUTDOWN_POWEROFF, 0, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -07001145}
1146
Rusty Russellb2b47c22007-07-26 10:41:02 -07001147/*
1148 * Panicing.
1149 *
1150 * Don't. But if you did, this is what happens.
1151 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001152static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
1153{
Rusty Russell091ebf02010-04-14 21:43:54 -06001154 hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0, 0);
Rusty Russellb2b47c22007-07-26 10:41:02 -07001155 /* The hcall won't return, but to keep gcc happy, we're "done". */
Rusty Russell07ad1572007-07-19 01:49:22 -07001156 return NOTIFY_DONE;
1157}
1158
1159static struct notifier_block paniced = {
1160 .notifier_call = lguest_panic
1161};
1162
Rusty Russellb2b47c22007-07-26 10:41:02 -07001163/* Setting up memory is fairly easy. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001164static __init char *lguest_memory_setup(void)
1165{
Rusty Russell2e04ef72009-07-30 16:03:45 -06001166 /*
Rusty Russell9f542882011-07-22 14:39:50 +09301167 * The Linux bootloader header contains an "e820" memory map: the
Rusty Russell2e04ef72009-07-30 16:03:45 -06001168 * Launcher populated the first entry with our memory limit.
1169 */
Yinghai Lud0be6bd2008-06-15 18:58:51 -07001170 e820_add_region(boot_params.e820_map[0].addr,
H. Peter Anvin30c82642007-10-15 17:13:22 -07001171 boot_params.e820_map[0].size,
1172 boot_params.e820_map[0].type);
Rusty Russellb2b47c22007-07-26 10:41:02 -07001173
1174 /* This string is for the boot messages. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001175 return "LGUEST";
1176}
1177
Rusty Russell2e04ef72009-07-30 16:03:45 -06001178/*
1179 * We will eventually use the virtio console device to produce console output,
Rusty Russelle1e72962007-10-25 15:02:50 +10001180 * but before that is set up we use LHCALL_NOTIFY on normal memory to produce
Rusty Russell2e04ef72009-07-30 16:03:45 -06001181 * console output.
1182 */
Rusty Russell19f15372007-10-22 11:24:21 +10001183static __init int early_put_chars(u32 vtermno, const char *buf, int count)
1184{
1185 char scratch[17];
1186 unsigned int len = count;
1187
Rusty Russell2e04ef72009-07-30 16:03:45 -06001188 /* We use a nul-terminated string, so we make a copy. Icky, huh? */
Rusty Russell19f15372007-10-22 11:24:21 +10001189 if (len > sizeof(scratch) - 1)
1190 len = sizeof(scratch) - 1;
1191 scratch[len] = '\0';
1192 memcpy(scratch, buf, len);
Rusty Russell091ebf02010-04-14 21:43:54 -06001193 hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0, 0);
Rusty Russell19f15372007-10-22 11:24:21 +10001194
1195 /* This routine returns the number of bytes actually written. */
1196 return len;
1197}
1198
Rusty Russell2e04ef72009-07-30 16:03:45 -06001199/*
1200 * Rebooting also tells the Host we're finished, but the RESTART flag tells the
1201 * Launcher to reboot us.
1202 */
Rusty Russella6bd8e12008-03-28 11:05:53 -05001203static void lguest_restart(char *reason)
1204{
Rusty Russell091ebf02010-04-14 21:43:54 -06001205 hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0, 0);
Rusty Russella6bd8e12008-03-28 11:05:53 -05001206}
1207
Rusty Russellb2b47c22007-07-26 10:41:02 -07001208/*G:050
1209 * Patching (Powerfully Placating Performance Pedants)
1210 *
Rusty Russella6bd8e12008-03-28 11:05:53 -05001211 * We have already seen that pv_ops structures let us replace simple native
1212 * instructions with calls to the appropriate back end all throughout the
1213 * kernel. This allows the same kernel to run as a Guest and as a native
Rusty Russellb2b47c22007-07-26 10:41:02 -07001214 * kernel, but it's slow because of all the indirect branches.
1215 *
1216 * Remember that David Wheeler quote about "Any problem in computer science can
1217 * be solved with another layer of indirection"? The rest of that quote is
1218 * "... But that usually will create another problem." This is the first of
1219 * those problems.
1220 *
1221 * Our current solution is to allow the paravirt back end to optionally patch
1222 * over the indirect calls to replace them with something more efficient. We
Rusty Russella32a8812009-06-12 22:27:02 -06001223 * patch two of the simplest of the most commonly called functions: disable
1224 * interrupts and save interrupts. We usually have 6 or 10 bytes to patch
1225 * into: the Guest versions of these operations are small enough that we can
1226 * fit comfortably.
Rusty Russellb2b47c22007-07-26 10:41:02 -07001227 *
1228 * First we need assembly templates of each of the patchable Guest operations,
Rusty Russell2e04ef72009-07-30 16:03:45 -06001229 * and these are in i386_head.S.
1230 */
Rusty Russellb2b47c22007-07-26 10:41:02 -07001231
1232/*G:060 We construct a table from the assembler templates: */
Rusty Russell07ad1572007-07-19 01:49:22 -07001233static const struct lguest_insns
1234{
1235 const char *start, *end;
1236} lguest_insns[] = {
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001237 [PARAVIRT_PATCH(pv_irq_ops.irq_disable)] = { lgstart_cli, lgend_cli },
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001238 [PARAVIRT_PATCH(pv_irq_ops.save_fl)] = { lgstart_pushf, lgend_pushf },
Rusty Russell07ad1572007-07-19 01:49:22 -07001239};
Rusty Russellb2b47c22007-07-26 10:41:02 -07001240
Rusty Russell2e04ef72009-07-30 16:03:45 -06001241/*
1242 * Now our patch routine is fairly simple (based on the native one in
Rusty Russellb2b47c22007-07-26 10:41:02 -07001243 * paravirt.c). If we have a replacement, we copy it in and return how much of
Rusty Russell2e04ef72009-07-30 16:03:45 -06001244 * the available space we used.
1245 */
Andi Kleenab144f52007-08-10 22:31:03 +02001246static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf,
1247 unsigned long addr, unsigned len)
Rusty Russell07ad1572007-07-19 01:49:22 -07001248{
1249 unsigned int insn_len;
1250
Rusty Russellb2b47c22007-07-26 10:41:02 -07001251 /* Don't do anything special if we don't have a replacement */
Rusty Russell07ad1572007-07-19 01:49:22 -07001252 if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
Andi Kleenab144f52007-08-10 22:31:03 +02001253 return paravirt_patch_default(type, clobber, ibuf, addr, len);
Rusty Russell07ad1572007-07-19 01:49:22 -07001254
1255 insn_len = lguest_insns[type].end - lguest_insns[type].start;
1256
Rusty Russell2e04ef72009-07-30 16:03:45 -06001257 /* Similarly if it can't fit (doesn't happen, but let's be thorough). */
Rusty Russell07ad1572007-07-19 01:49:22 -07001258 if (len < insn_len)
Andi Kleenab144f52007-08-10 22:31:03 +02001259 return paravirt_patch_default(type, clobber, ibuf, addr, len);
Rusty Russell07ad1572007-07-19 01:49:22 -07001260
Rusty Russellb2b47c22007-07-26 10:41:02 -07001261 /* Copy in our instructions. */
Andi Kleenab144f52007-08-10 22:31:03 +02001262 memcpy(ibuf, lguest_insns[type].start, insn_len);
Rusty Russell07ad1572007-07-19 01:49:22 -07001263 return insn_len;
1264}
1265
Rusty Russell2e04ef72009-07-30 16:03:45 -06001266/*G:029
1267 * Once we get to lguest_init(), we know we're a Guest. The various
Rusty Russella6bd8e12008-03-28 11:05:53 -05001268 * pv_ops structures in the kernel provide points for (almost) every routine we
Rusty Russell2e04ef72009-07-30 16:03:45 -06001269 * have to override to avoid privileged instructions.
1270 */
Rusty Russell814a0e52007-10-22 11:29:44 +10001271__init void lguest_init(void)
Rusty Russell07ad1572007-07-19 01:49:22 -07001272{
Rusty Russell2e04ef72009-07-30 16:03:45 -06001273 /* We're under lguest. */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001274 pv_info.name = "lguest";
Rusty Russell2e04ef72009-07-30 16:03:45 -06001275 /* Paravirt is enabled. */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001276 pv_info.paravirt_enabled = 1;
Rusty Russell2e04ef72009-07-30 16:03:45 -06001277 /* We're running at privilege level 1, not 0 as normal. */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001278 pv_info.kernel_rpl = 1;
Rusty Russell2e04ef72009-07-30 16:03:45 -06001279 /* Everyone except Xen runs with this set. */
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -06001280 pv_info.shared_kernel_pmd = 1;
Rusty Russell07ad1572007-07-19 01:49:22 -07001281
Rusty Russell2e04ef72009-07-30 16:03:45 -06001282 /*
1283 * We set up all the lguest overrides for sensitive operations. These
1284 * are detailed with the operations themselves.
1285 */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001286
Rusty Russell2e04ef72009-07-30 16:03:45 -06001287 /* Interrupt-related operations */
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -08001288 pv_irq_ops.save_fl = PV_CALLEE_SAVE(save_fl);
Rusty Russell61f4bc82009-06-12 22:27:03 -06001289 pv_irq_ops.restore_fl = __PV_IS_CALLEE_SAVE(lg_restore_fl);
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -08001290 pv_irq_ops.irq_disable = PV_CALLEE_SAVE(irq_disable);
Rusty Russell61f4bc82009-06-12 22:27:03 -06001291 pv_irq_ops.irq_enable = __PV_IS_CALLEE_SAVE(lg_irq_enable);
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001292 pv_irq_ops.safe_halt = lguest_safe_halt;
1293
Rusty Russell2e04ef72009-07-30 16:03:45 -06001294 /* Setup operations */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001295 pv_init_ops.patch = lguest_patch;
1296
Rusty Russell2e04ef72009-07-30 16:03:45 -06001297 /* Intercepts of various CPU instructions */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001298 pv_cpu_ops.load_gdt = lguest_load_gdt;
1299 pv_cpu_ops.cpuid = lguest_cpuid;
1300 pv_cpu_ops.load_idt = lguest_load_idt;
1301 pv_cpu_ops.iret = lguest_iret;
H. Peter Anvinfaca6222008-01-30 13:31:02 +01001302 pv_cpu_ops.load_sp0 = lguest_load_sp0;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001303 pv_cpu_ops.load_tr_desc = lguest_load_tr_desc;
1304 pv_cpu_ops.set_ldt = lguest_set_ldt;
1305 pv_cpu_ops.load_tls = lguest_load_tls;
1306 pv_cpu_ops.set_debugreg = lguest_set_debugreg;
1307 pv_cpu_ops.clts = lguest_clts;
1308 pv_cpu_ops.read_cr0 = lguest_read_cr0;
1309 pv_cpu_ops.write_cr0 = lguest_write_cr0;
1310 pv_cpu_ops.read_cr4 = lguest_read_cr4;
1311 pv_cpu_ops.write_cr4 = lguest_write_cr4;
1312 pv_cpu_ops.write_gdt_entry = lguest_write_gdt_entry;
1313 pv_cpu_ops.write_idt_entry = lguest_write_idt_entry;
1314 pv_cpu_ops.wbinvd = lguest_wbinvd;
Jeremy Fitzhardinge224101e2009-02-18 11:18:57 -08001315 pv_cpu_ops.start_context_switch = paravirt_start_context_switch;
1316 pv_cpu_ops.end_context_switch = lguest_end_context_switch;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001317
Rusty Russell2e04ef72009-07-30 16:03:45 -06001318 /* Pagetable management */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001319 pv_mmu_ops.write_cr3 = lguest_write_cr3;
1320 pv_mmu_ops.flush_tlb_user = lguest_flush_tlb_user;
1321 pv_mmu_ops.flush_tlb_single = lguest_flush_tlb_single;
1322 pv_mmu_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
1323 pv_mmu_ops.set_pte = lguest_set_pte;
1324 pv_mmu_ops.set_pte_at = lguest_set_pte_at;
1325 pv_mmu_ops.set_pmd = lguest_set_pmd;
Matias Zabaljaureguiacdd0b62009-06-12 22:27:07 -06001326#ifdef CONFIG_X86_PAE
1327 pv_mmu_ops.set_pte_atomic = lguest_set_pte_atomic;
1328 pv_mmu_ops.pte_clear = lguest_pte_clear;
1329 pv_mmu_ops.pmd_clear = lguest_pmd_clear;
1330 pv_mmu_ops.set_pud = lguest_set_pud;
1331#endif
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001332 pv_mmu_ops.read_cr2 = lguest_read_cr2;
1333 pv_mmu_ops.read_cr3 = lguest_read_cr3;
Jeremy Fitzhardinge8965c1c2007-10-16 11:51:29 -07001334 pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
Jeremy Fitzhardingeb407fc52009-02-17 23:46:21 -08001335 pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mmu_mode;
Rusty Russellb7ff99e2009-03-30 21:55:23 -06001336 pv_mmu_ops.pte_update = lguest_pte_update;
1337 pv_mmu_ops.pte_update_defer = lguest_pte_update;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001338
Rusty Russell07ad1572007-07-19 01:49:22 -07001339#ifdef CONFIG_X86_LOCAL_APIC
Rusty Russell2e04ef72009-07-30 16:03:45 -06001340 /* APIC read/write intercepts */
Yinghai Luc1eeb2d2009-02-16 23:02:14 -08001341 set_lguest_basic_apic_ops();
Rusty Russell07ad1572007-07-19 01:49:22 -07001342#endif
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001343
Thomas Gleixner6b18ae32009-08-20 10:19:54 +02001344 x86_init.resources.memory_setup = lguest_memory_setup;
Thomas Gleixner66bcaf02009-08-20 09:59:09 +02001345 x86_init.irqs.intr_init = lguest_init_IRQ;
Thomas Gleixner845b3942009-08-19 15:37:03 +02001346 x86_init.timers.timer_init = lguest_time_init;
Thomas Gleixner2d826402009-08-20 17:06:25 +02001347 x86_platform.calibrate_tsc = lguest_tsc_khz;
Feng Tang7bd867d2009-09-10 10:48:56 +08001348 x86_platform.get_wallclock = lguest_get_wallclock;
Thomas Gleixner6b18ae32009-08-20 10:19:54 +02001349
Rusty Russell2e04ef72009-07-30 16:03:45 -06001350 /*
1351 * Now is a good time to look at the implementations of these functions
1352 * before returning to the rest of lguest_init().
1353 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001354
Rusty Russell2e04ef72009-07-30 16:03:45 -06001355 /*G:070
1356 * Now we've seen all the paravirt_ops, we return to
Rusty Russellb2b47c22007-07-26 10:41:02 -07001357 * lguest_init() where the rest of the fairly chaotic boot setup
Rusty Russell2e04ef72009-07-30 16:03:45 -06001358 * occurs.
1359 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001360
Rusty Russell2e04ef72009-07-30 16:03:45 -06001361 /*
1362 * The stack protector is a weird thing where gcc places a canary
Rusty Russell2cb78782009-06-03 14:52:24 +09301363 * value on the stack and then checks it on return. This file is
1364 * compiled with -fno-stack-protector it, so we got this far without
1365 * problems. The value of the canary is kept at offset 20 from the
1366 * %gs register, so we need to set that up before calling C functions
Rusty Russell2e04ef72009-07-30 16:03:45 -06001367 * in other files.
1368 */
Rusty Russell2cb78782009-06-03 14:52:24 +09301369 setup_stack_canary_segment(0);
Rusty Russell2e04ef72009-07-30 16:03:45 -06001370
1371 /*
1372 * We could just call load_stack_canary_segment(), but we might as well
1373 * call switch_to_new_gdt() which loads the whole table and sets up the
1374 * per-cpu segment descriptor register %fs as well.
1375 */
Rusty Russell2cb78782009-06-03 14:52:24 +09301376 switch_to_new_gdt(0);
1377
Rusty Russell2e04ef72009-07-30 16:03:45 -06001378 /*
1379 * The Host<->Guest Switcher lives at the top of our address space, and
Rusty Russella6bd8e12008-03-28 11:05:53 -05001380 * the Host told us how big it is when we made LGUEST_INIT hypercall:
Rusty Russell2e04ef72009-07-30 16:03:45 -06001381 * it put the answer in lguest_data.reserve_mem
1382 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001383 reserve_top_address(lguest_data.reserve_mem);
1384
Rusty Russell2e04ef72009-07-30 16:03:45 -06001385 /*
1386 * If we don't initialize the lock dependency checker now, it crashes
Rusty Russellcdae0ad2009-09-23 22:26:42 -06001387 * atomic_notifier_chain_register, then paravirt_disable_iospace.
Rusty Russell2e04ef72009-07-30 16:03:45 -06001388 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001389 lockdep_init();
1390
Rusty Russellcdae0ad2009-09-23 22:26:42 -06001391 /* Hook in our special panic hypercall code. */
1392 atomic_notifier_chain_register(&panic_notifier_list, &paniced);
1393
Rusty Russell2e04ef72009-07-30 16:03:45 -06001394 /*
1395 * The IDE code spends about 3 seconds probing for disks: if we reserve
Rusty Russellb2b47c22007-07-26 10:41:02 -07001396 * all the I/O ports up front it can't get them and so doesn't probe.
1397 * Other device drivers are similar (but less severe). This cuts the
Rusty Russell2e04ef72009-07-30 16:03:45 -06001398 * kernel boot time on my machine from 4.1 seconds to 0.45 seconds.
1399 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001400 paravirt_disable_iospace();
1401
Rusty Russell2e04ef72009-07-30 16:03:45 -06001402 /*
1403 * This is messy CPU setup stuff which the native boot code does before
1404 * start_kernel, so we have to do, too:
1405 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001406 cpu_detect(&new_cpu_data);
1407 /* head.S usually sets up the first capability word, so do it here. */
1408 new_cpu_data.x86_capability[0] = cpuid_edx(1);
1409
1410 /* Math is always hard! */
1411 new_cpu_data.hard_math = 1;
1412
Rusty Russella6bd8e12008-03-28 11:05:53 -05001413 /* We don't have features. We have puppies! Puppies! */
Rusty Russell07ad1572007-07-19 01:49:22 -07001414#ifdef CONFIG_X86_MCE
1415 mce_disabled = 1;
1416#endif
Rusty Russell07ad1572007-07-19 01:49:22 -07001417#ifdef CONFIG_ACPI
1418 acpi_disabled = 1;
Rusty Russell07ad1572007-07-19 01:49:22 -07001419#endif
1420
Rusty Russell2e04ef72009-07-30 16:03:45 -06001421 /*
1422 * We set the preferred console to "hvc". This is the "hypervisor
Rusty Russellb2b47c22007-07-26 10:41:02 -07001423 * virtual console" driver written by the PowerPC people, which we also
Rusty Russell2e04ef72009-07-30 16:03:45 -06001424 * adapted for lguest's use.
1425 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001426 add_preferred_console("hvc", 0, NULL);
1427
Rusty Russell19f15372007-10-22 11:24:21 +10001428 /* Register our very early console. */
1429 virtio_cons_early_init(early_put_chars);
1430
Rusty Russell2e04ef72009-07-30 16:03:45 -06001431 /*
1432 * Last of all, we set the power management poweroff hook to point to
Rusty Russella6bd8e12008-03-28 11:05:53 -05001433 * the Guest routine to power off, and the reboot hook to our restart
Rusty Russell2e04ef72009-07-30 16:03:45 -06001434 * routine.
1435 */
Rusty Russell07ad1572007-07-19 01:49:22 -07001436 pm_power_off = lguest_power_off;
Balaji Raoec04b132007-12-28 14:26:24 +05301437 machine_ops.restart = lguest_restart;
Rusty Russella6bd8e12008-03-28 11:05:53 -05001438
Rusty Russell2e04ef72009-07-30 16:03:45 -06001439 /*
1440 * Now we're set up, call i386_start_kernel() in head32.c and we proceed
1441 * to boot as normal. It never returns.
1442 */
Yinghai Luf0d43102008-05-29 12:56:36 -07001443 i386_start_kernel();
Rusty Russell07ad1572007-07-19 01:49:22 -07001444}
Rusty Russellb2b47c22007-07-26 10:41:02 -07001445/*
1446 * This marks the end of stage II of our journey, The Guest.
1447 *
Rusty Russelle1e72962007-10-25 15:02:50 +10001448 * It is now time for us to explore the layer of virtual drivers and complete
1449 * our understanding of the Guest in "make Drivers".
Rusty Russellb2b47c22007-07-26 10:41:02 -07001450 */