blob: 48ee4f9435f418c45439ab02a1926a1c054cb071 [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
10 * (such as the example in Documentation/lguest/lguest.c) is called the
11 * 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
25 * "paravirt" structures with our Guest versions, then boot like normal. :*/
Rusty Russellf938d2c2007-07-26 10:41:02 -070026
27/*
Rusty Russell07ad1572007-07-19 01:49:22 -070028 * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
29 *
30 * This program is free software; you can redistribute it and/or modify
31 * it under the terms of the GNU General Public License as published by
32 * the Free Software Foundation; either version 2 of the License, or
33 * (at your option) any later version.
34 *
35 * This program is distributed in the hope that it will be useful, but
36 * WITHOUT ANY WARRANTY; without even the implied warranty of
37 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
38 * NON INFRINGEMENT. See the GNU General Public License for more
39 * details.
40 *
41 * You should have received a copy of the GNU General Public License
42 * along with this program; if not, write to the Free Software
43 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
44 */
45#include <linux/kernel.h>
46#include <linux/start_kernel.h>
47#include <linux/string.h>
48#include <linux/console.h>
49#include <linux/screen_info.h>
50#include <linux/irq.h>
51#include <linux/interrupt.h>
Rusty Russelld7e28ff2007-07-19 01:49:23 -070052#include <linux/clocksource.h>
53#include <linux/clockchips.h>
Rusty Russell07ad1572007-07-19 01:49:22 -070054#include <linux/lguest.h>
55#include <linux/lguest_launcher.h>
Rusty Russell19f15372007-10-22 11:24:21 +100056#include <linux/virtio_console.h>
Jeff Garzik4cfe6c32007-10-25 14:15:09 +100057#include <linux/pm.h>
Ingo Molnar7be42002008-07-20 17:04:57 +020058#include <asm/apic.h>
Harvey Harrisoncbc34972008-02-13 13:14:35 -080059#include <asm/lguest.h>
Rusty Russell07ad1572007-07-19 01:49:22 -070060#include <asm/paravirt.h>
61#include <asm/param.h>
62#include <asm/page.h>
63#include <asm/pgtable.h>
64#include <asm/desc.h>
65#include <asm/setup.h>
66#include <asm/e820.h>
67#include <asm/mce.h>
68#include <asm/io.h>
Jes Sorensen625efab2007-10-22 11:03:28 +100069#include <asm/i387.h>
Balaji Raoec04b132007-12-28 14:26:24 +053070#include <asm/reboot.h> /* for struct machine_ops */
Rusty Russell07ad1572007-07-19 01:49:22 -070071
Rusty Russellb2b47c22007-07-26 10:41:02 -070072/*G:010 Welcome to the Guest!
73 *
74 * The Guest in our tale is a simple creature: identical to the Host but
75 * behaving in simplified but equivalent ways. In particular, the Guest is the
76 * same kernel as the Host (or at least, built from the same source code). :*/
77
Rusty Russell07ad1572007-07-19 01:49:22 -070078struct lguest_data lguest_data = {
79 .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
80 .noirq_start = (u32)lguest_noirq_start,
81 .noirq_end = (u32)lguest_noirq_end,
Rusty Russell47436aa2007-10-22 11:03:36 +100082 .kernel_address = PAGE_OFFSET,
Rusty Russell07ad1572007-07-19 01:49:22 -070083 .blocked_interrupts = { 1 }, /* Block timer interrupts */
Rusty Russellc18acd72007-10-22 11:03:35 +100084 .syscall_vec = SYSCALL_VECTOR,
Rusty Russell07ad1572007-07-19 01:49:22 -070085};
Rusty Russell07ad1572007-07-19 01:49:22 -070086
Rusty Russell633872b2007-11-05 21:55:57 +110087/*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a
Rusty Russellb2b47c22007-07-26 10:41:02 -070088 * ring buffer of stored hypercalls which the Host will run though next time we
89 * do a normal hypercall. Each entry in the ring has 4 slots for the hypercall
90 * arguments, and a "hcall_status" word which is 0 if the call is ready to go,
91 * and 255 once the Host has finished with it.
92 *
93 * If we come around to a slot which hasn't been finished, then the table is
94 * full and we just make the hypercall directly. This has the nice side
95 * effect of causing the Host to run all the stored calls in the ring buffer
96 * which empties it for next time! */
Adrian Bunk9b56fdb2007-11-02 16:43:10 +010097static void async_hcall(unsigned long call, unsigned long arg1,
98 unsigned long arg2, unsigned long arg3)
Rusty Russell07ad1572007-07-19 01:49:22 -070099{
100 /* Note: This code assumes we're uniprocessor. */
101 static unsigned int next_call;
102 unsigned long flags;
103
Rusty Russellb2b47c22007-07-26 10:41:02 -0700104 /* Disable interrupts if not already disabled: we don't want an
105 * interrupt handler making a hypercall while we're already doing
106 * one! */
Rusty Russell07ad1572007-07-19 01:49:22 -0700107 local_irq_save(flags);
108 if (lguest_data.hcall_status[next_call] != 0xFF) {
109 /* Table full, so do normal hcall which will flush table. */
110 hcall(call, arg1, arg2, arg3);
111 } else {
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000112 lguest_data.hcalls[next_call].arg0 = call;
113 lguest_data.hcalls[next_call].arg1 = arg1;
114 lguest_data.hcalls[next_call].arg2 = arg2;
115 lguest_data.hcalls[next_call].arg3 = arg3;
Rusty Russellb2b47c22007-07-26 10:41:02 -0700116 /* Arguments must all be written before we mark it to go */
Rusty Russell07ad1572007-07-19 01:49:22 -0700117 wmb();
118 lguest_data.hcall_status[next_call] = 0;
119 if (++next_call == LHCALL_RING_SIZE)
120 next_call = 0;
121 }
122 local_irq_restore(flags);
123}
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100124
Rusty Russell633872b2007-11-05 21:55:57 +1100125/*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first
126 * real optimization trick!
127 *
128 * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
129 * them as a batch when lazy_mode is eventually turned off. Because hypercalls
130 * are reasonably expensive, batching them up makes sense. For example, a
131 * large munmap might update dozens of page table entries: that code calls
132 * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
133 * lguest_leave_lazy_mode().
134 *
135 * So, when we're in lazy mode, we call async_hcall() to store the call for
Rusty Russella6bd8e12008-03-28 11:05:53 -0500136 * future processing: */
Adrian Bunk9b56fdb2007-11-02 16:43:10 +0100137static void lazy_hcall(unsigned long call,
138 unsigned long arg1,
139 unsigned long arg2,
140 unsigned long arg3)
141{
142 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
143 hcall(call, arg1, arg2, arg3);
144 else
145 async_hcall(call, arg1, arg2, arg3);
146}
Rusty Russell633872b2007-11-05 21:55:57 +1100147
148/* When lazy mode is turned off reset the per-cpu lazy mode variable and then
Rusty Russella6bd8e12008-03-28 11:05:53 -0500149 * issue the do-nothing hypercall to flush any stored calls. */
Rusty Russell633872b2007-11-05 21:55:57 +1100150static void lguest_leave_lazy_mode(void)
151{
152 paravirt_leave_lazy(paravirt_get_lazy_mode());
153 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
154}
Rusty Russell07ad1572007-07-19 01:49:22 -0700155
Rusty Russellb2b47c22007-07-26 10:41:02 -0700156/*G:033
Rusty Russelle1e72962007-10-25 15:02:50 +1000157 * After that diversion we return to our first native-instruction
158 * replacements: four functions for interrupt control.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700159 *
160 * The simplest way of implementing these would be to have "turn interrupts
161 * off" and "turn interrupts on" hypercalls. Unfortunately, this is too slow:
162 * these are by far the most commonly called functions of those we override.
163 *
164 * So instead we keep an "irq_enabled" field inside our "struct lguest_data",
165 * which the Guest can update with a single instruction. The Host knows to
Rusty Russella6bd8e12008-03-28 11:05:53 -0500166 * check there before it tries to deliver an interrupt.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700167 */
168
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100169/* save_flags() is expected to return the processor state (ie. "flags"). The
170 * flags word contains all kind of stuff, but in practice Linux only cares
Rusty Russellb2b47c22007-07-26 10:41:02 -0700171 * about the interrupt flag. Our "save_flags()" just returns that. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700172static unsigned long save_fl(void)
173{
174 return lguest_data.irq_enabled;
175}
176
Rusty Russelle1e72962007-10-25 15:02:50 +1000177/* restore_flags() just sets the flags back to the value given. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700178static void restore_fl(unsigned long flags)
179{
Rusty Russell07ad1572007-07-19 01:49:22 -0700180 lguest_data.irq_enabled = flags;
181}
182
Rusty Russellb2b47c22007-07-26 10:41:02 -0700183/* Interrupts go off... */
Rusty Russell07ad1572007-07-19 01:49:22 -0700184static void irq_disable(void)
185{
186 lguest_data.irq_enabled = 0;
187}
188
Rusty Russellb2b47c22007-07-26 10:41:02 -0700189/* Interrupts go on... */
Rusty Russell07ad1572007-07-19 01:49:22 -0700190static void irq_enable(void)
191{
Rusty Russell07ad1572007-07-19 01:49:22 -0700192 lguest_data.irq_enabled = X86_EFLAGS_IF;
193}
Rusty Russellf56a3842007-07-26 10:41:05 -0700194/*:*/
195/*M:003 Note that we don't check for outstanding interrupts when we re-enable
196 * them (or when we unmask an interrupt). This seems to work for the moment,
197 * since interrupts are rare and we'll just get the interrupt on the next timer
Rusty Russella6bd8e12008-03-28 11:05:53 -0500198 * tick, but now we can run with CONFIG_NO_HZ, we should revisit this. One way
Rusty Russellf56a3842007-07-26 10:41:05 -0700199 * would be to put the "irq_enabled" field in a page by itself, and have the
200 * Host write-protect it when an interrupt comes in when irqs are disabled.
Rusty Russella6bd8e12008-03-28 11:05:53 -0500201 * There will then be a page fault as soon as interrupts are re-enabled.
202 *
203 * A better method is to implement soft interrupt disable generally for x86:
204 * instead of disabling interrupts, we set a flag. If an interrupt does come
205 * in, we then disable them for real. This is uncommon, so we could simply use
206 * a hypercall for interrupt control and not worry about efficiency. :*/
Rusty Russell07ad1572007-07-19 01:49:22 -0700207
Rusty Russellb2b47c22007-07-26 10:41:02 -0700208/*G:034
209 * The Interrupt Descriptor Table (IDT).
210 *
211 * The IDT tells the processor what to do when an interrupt comes in. Each
212 * entry in the table is a 64-bit descriptor: this holds the privilege level,
213 * address of the handler, and... well, who cares? The Guest just asks the
214 * Host to make the change anyway, because the Host controls the real IDT.
215 */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100216static void lguest_write_idt_entry(gate_desc *dt,
217 int entrynum, const gate_desc *g)
Rusty Russell07ad1572007-07-19 01:49:22 -0700218{
Rusty Russella6bd8e12008-03-28 11:05:53 -0500219 /* The gate_desc structure is 8 bytes long: we hand it to the Host in
220 * two 32-bit chunks. The whole 32-bit kernel used to hand descriptors
221 * around like this; typesafety wasn't a big concern in Linux's early
222 * years. */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100223 u32 *desc = (u32 *)g;
Rusty Russellb2b47c22007-07-26 10:41:02 -0700224 /* Keep the local copy up to date. */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100225 native_write_idt_entry(dt, entrynum, g);
Rusty Russellb2b47c22007-07-26 10:41:02 -0700226 /* Tell Host about this new entry. */
Glauber de Oliveira Costa8d947342008-01-30 13:31:12 +0100227 hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]);
Rusty Russell07ad1572007-07-19 01:49:22 -0700228}
229
Rusty Russellb2b47c22007-07-26 10:41:02 -0700230/* Changing to a different IDT is very rare: we keep the IDT up-to-date every
231 * time it is written, so we can simply loop through all entries and tell the
232 * Host about them. */
Glauber de Oliveira Costa6b68f012008-01-30 13:31:12 +0100233static void lguest_load_idt(const struct desc_ptr *desc)
Rusty Russell07ad1572007-07-19 01:49:22 -0700234{
235 unsigned int i;
236 struct desc_struct *idt = (void *)desc->address;
237
238 for (i = 0; i < (desc->size+1)/8; i++)
239 hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
240}
241
Rusty Russellb2b47c22007-07-26 10:41:02 -0700242/*
243 * The Global Descriptor Table.
244 *
245 * The Intel architecture defines another table, called the Global Descriptor
246 * Table (GDT). You tell the CPU where it is (and its size) using the "lgdt"
247 * instruction, and then several other instructions refer to entries in the
248 * table. There are three entries which the Switcher needs, so the Host simply
249 * controls the entire thing and the Guest asks it to make changes using the
250 * LOAD_GDT hypercall.
251 *
252 * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY
253 * hypercall and use that repeatedly to load a new IDT. I don't think it
Rusty Russella6bd8e12008-03-28 11:05:53 -0500254 * really matters, but wouldn't it be nice if they were the same? Wouldn't
255 * it be even better if you were the one to send the patch to fix it?
Rusty Russellb2b47c22007-07-26 10:41:02 -0700256 */
Glauber de Oliveira Costa6b68f012008-01-30 13:31:12 +0100257static void lguest_load_gdt(const struct desc_ptr *desc)
Rusty Russell07ad1572007-07-19 01:49:22 -0700258{
259 BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
260 hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
261}
262
Rusty Russellb2b47c22007-07-26 10:41:02 -0700263/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
264 * then tell the Host to reload the entire thing. This operation is so rare
265 * that this naive implementation is reasonable. */
Glauber de Oliveira Costa014b15b2008-01-30 13:31:13 +0100266static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
267 const void *desc, int type)
Rusty Russell07ad1572007-07-19 01:49:22 -0700268{
Glauber de Oliveira Costa014b15b2008-01-30 13:31:13 +0100269 native_write_gdt_entry(dt, entrynum, desc, type);
Rusty Russell07ad1572007-07-19 01:49:22 -0700270 hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
271}
272
Rusty Russellb2b47c22007-07-26 10:41:02 -0700273/* OK, I lied. There are three "thread local storage" GDT entries which change
274 * on every context switch (these three entries are how glibc implements
275 * __thread variables). So we have a hypercall specifically for this case. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700276static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
277{
Rusty Russell0d027c02007-08-09 20:57:13 +1000278 /* There's one problem which normal hardware doesn't have: the Host
279 * can't handle us removing entries we're currently using. So we clear
280 * the GS register here: if it's needed it'll be reloaded anyway. */
281 loadsegment(gs, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700282 lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
283}
284
Rusty Russellb2b47c22007-07-26 10:41:02 -0700285/*G:038 That's enough excitement for now, back to ploughing through each of
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700286 * the different pv_ops structures (we're about 1/3 of the way through).
Rusty Russellb2b47c22007-07-26 10:41:02 -0700287 *
288 * This is the Local Descriptor Table, another weird Intel thingy. Linux only
289 * uses this for some strange applications like Wine. We don't do anything
290 * here, so they'll get an informative and friendly Segmentation Fault. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700291static void lguest_set_ldt(const void *addr, unsigned entries)
292{
293}
294
Rusty Russellb2b47c22007-07-26 10:41:02 -0700295/* This loads a GDT entry into the "Task Register": that entry points to a
296 * structure called the Task State Segment. Some comments scattered though the
297 * kernel code indicate that this used for task switching in ages past, along
298 * with blood sacrifice and astrology.
299 *
300 * Now there's nothing interesting in here that we don't get told elsewhere.
301 * But the native version uses the "ltr" instruction, which makes the Host
302 * complain to the Guest about a Segmentation Fault and it'll oops. So we
303 * override the native version with a do-nothing version. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700304static void lguest_load_tr_desc(void)
305{
306}
307
Rusty Russellb2b47c22007-07-26 10:41:02 -0700308/* The "cpuid" instruction is a way of querying both the CPU identity
309 * (manufacturer, model, etc) and its features. It was introduced before the
Rusty Russella6bd8e12008-03-28 11:05:53 -0500310 * Pentium in 1993 and keeps getting extended by both Intel, AMD and others.
311 * As you might imagine, after a decade and a half this treatment, it is now a
312 * giant ball of hair. Its entry in the current Intel manual runs to 28 pages.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700313 *
314 * This instruction even it has its own Wikipedia entry. The Wikipedia entry
315 * has been translated into 4 languages. I am not making this up!
316 *
317 * We could get funky here and identify ourselves as "GenuineLguest", but
318 * instead we just use the real "cpuid" instruction. Then I pretty much turned
319 * off feature bits until the Guest booted. (Don't say that: you'll damage
320 * lguest sales!) Shut up, inner voice! (Hey, just pointing out that this is
321 * hardly future proof.) Noone's listening! They don't like you anyway,
322 * parenthetic weirdo!
323 *
324 * Replacing the cpuid so we can turn features off is great for the kernel, but
325 * anyone (including userspace) can just use the raw "cpuid" instruction and
326 * the Host won't even notice since it isn't privileged. So we try not to get
327 * too worked up about it. */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100328static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
329 unsigned int *cx, unsigned int *dx)
Rusty Russell07ad1572007-07-19 01:49:22 -0700330{
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100331 int function = *ax;
Rusty Russell07ad1572007-07-19 01:49:22 -0700332
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100333 native_cpuid(ax, bx, cx, dx);
Rusty Russell07ad1572007-07-19 01:49:22 -0700334 switch (function) {
335 case 1: /* Basic feature request. */
336 /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100337 *cx &= 0x00002201;
Rusty Russell3fabc552008-03-11 09:35:56 -0500338 /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU. */
339 *dx &= 0x07808111;
Rusty Russellb2b47c22007-07-26 10:41:02 -0700340 /* The Host can do a nice optimization if it knows that the
341 * kernel mappings (addresses above 0xC0000000 or whatever
342 * PAGE_OFFSET is set to) haven't changed. But Linux calls
343 * flush_tlb_user() for both user and kernel mappings unless
344 * the Page Global Enable (PGE) feature bit is set. */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100345 *dx |= 0x00002000;
Rusty Russell07ad1572007-07-19 01:49:22 -0700346 break;
347 case 0x80000000:
348 /* Futureproof this a little: if they ask how much extended
Rusty Russellb2b47c22007-07-26 10:41:02 -0700349 * processor information there is, limit it to known fields. */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100350 if (*ax > 0x80000008)
351 *ax = 0x80000008;
Rusty Russell07ad1572007-07-19 01:49:22 -0700352 break;
353 }
354}
355
Rusty Russellb2b47c22007-07-26 10:41:02 -0700356/* Intel has four control registers, imaginatively named cr0, cr2, cr3 and cr4.
357 * I assume there's a cr1, but it hasn't bothered us yet, so we'll not bother
358 * it. The Host needs to know when the Guest wants to change them, so we have
359 * a whole series of functions like read_cr0() and write_cr0().
360 *
Rusty Russelle1e72962007-10-25 15:02:50 +1000361 * We start with cr0. cr0 allows you to turn on and off all kinds of basic
Rusty Russellb2b47c22007-07-26 10:41:02 -0700362 * features, but Linux only really cares about one: the horrifically-named Task
363 * Switched (TS) bit at bit 3 (ie. 8)
364 *
365 * What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if
366 * the floating point unit is used. Which allows us to restore FPU state
367 * lazily after a task switch, and Linux uses that gratefully, but wouldn't a
368 * name like "FPUTRAP bit" be a little less cryptic?
369 *
370 * We store cr0 (and cr3) locally, because the Host never changes it. The
371 * Guest sometimes wants to read it and we'd prefer not to bother the Host
372 * unnecessarily. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700373static unsigned long current_cr0, current_cr3;
374static void lguest_write_cr0(unsigned long val)
375{
Rusty Russell25c47bb2007-10-25 14:09:53 +1000376 lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700377 current_cr0 = val;
378}
379
380static unsigned long lguest_read_cr0(void)
381{
382 return current_cr0;
383}
384
Rusty Russellb2b47c22007-07-26 10:41:02 -0700385/* Intel provided a special instruction to clear the TS bit for people too cool
386 * to use write_cr0() to do it. This "clts" instruction is faster, because all
387 * the vowels have been optimized out. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700388static void lguest_clts(void)
389{
390 lazy_hcall(LHCALL_TS, 0, 0, 0);
Rusty Russell25c47bb2007-10-25 14:09:53 +1000391 current_cr0 &= ~X86_CR0_TS;
Rusty Russell07ad1572007-07-19 01:49:22 -0700392}
393
Rusty Russelle1e72962007-10-25 15:02:50 +1000394/* cr2 is the virtual address of the last page fault, which the Guest only ever
Rusty Russellb2b47c22007-07-26 10:41:02 -0700395 * reads. The Host kindly writes this into our "struct lguest_data", so we
396 * just read it out of there. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700397static unsigned long lguest_read_cr2(void)
398{
399 return lguest_data.cr2;
400}
401
Rusty Russelle1e72962007-10-25 15:02:50 +1000402/* cr3 is the current toplevel pagetable page: the principle is the same as
Rusty Russellb2b47c22007-07-26 10:41:02 -0700403 * cr0. Keep a local copy, and tell the Host when it changes. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700404static void lguest_write_cr3(unsigned long cr3)
405{
406 lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
407 current_cr3 = cr3;
408}
409
410static unsigned long lguest_read_cr3(void)
411{
412 return current_cr3;
413}
414
Rusty Russelle1e72962007-10-25 15:02:50 +1000415/* cr4 is used to enable and disable PGE, but we don't care. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700416static unsigned long lguest_read_cr4(void)
417{
418 return 0;
419}
420
421static void lguest_write_cr4(unsigned long val)
422{
423}
424
Rusty Russellb2b47c22007-07-26 10:41:02 -0700425/*
426 * Page Table Handling.
427 *
428 * Now would be a good time to take a rest and grab a coffee or similarly
429 * relaxing stimulant. The easy parts are behind us, and the trek gradually
430 * winds uphill from here.
431 *
432 * Quick refresher: memory is divided into "pages" of 4096 bytes each. The CPU
433 * maps virtual addresses to physical addresses using "page tables". We could
434 * use one huge index of 1 million entries: each address is 4 bytes, so that's
435 * 1024 pages just to hold the page tables. But since most virtual addresses
Rusty Russelle1e72962007-10-25 15:02:50 +1000436 * are unused, we use a two level index which saves space. The cr3 register
Rusty Russellb2b47c22007-07-26 10:41:02 -0700437 * contains the physical address of the top level "page directory" page, which
438 * contains physical addresses of up to 1024 second-level pages. Each of these
439 * second level pages contains up to 1024 physical addresses of actual pages,
440 * or Page Table Entries (PTEs).
441 *
442 * Here's a diagram, where arrows indicate physical addresses:
443 *
Rusty Russelle1e72962007-10-25 15:02:50 +1000444 * cr3 ---> +---------+
Rusty Russellb2b47c22007-07-26 10:41:02 -0700445 * | --------->+---------+
446 * | | | PADDR1 |
447 * Top-level | | PADDR2 |
448 * (PMD) page | | |
449 * | | Lower-level |
450 * | | (PTE) page |
451 * | | | |
452 * .... ....
453 *
454 * So to convert a virtual address to a physical address, we look up the top
455 * level, which points us to the second level, which gives us the physical
456 * address of that page. If the top level entry was not present, or the second
457 * level entry was not present, then the virtual address is invalid (we
458 * say "the page was not mapped").
459 *
460 * Put another way, a 32-bit virtual address is divided up like so:
461 *
462 * 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
463 * |<---- 10 bits ---->|<---- 10 bits ---->|<------ 12 bits ------>|
464 * Index into top Index into second Offset within page
465 * page directory page pagetable page
466 *
467 * The kernel spends a lot of time changing both the top-level page directory
468 * and lower-level pagetable pages. The Guest doesn't know physical addresses,
469 * so while it maintains these page tables exactly like normal, it also needs
470 * to keep the Host informed whenever it makes a change: the Host will create
471 * the real page tables based on the Guests'.
472 */
473
474/* The Guest calls this to set a second-level entry (pte), ie. to map a page
475 * into a process' address space. We set the entry then tell the Host the
476 * toplevel and address this corresponds to. The Guest uses one pagetable per
477 * process, so we need to tell the Host which one we're changing (mm->pgd). */
Rusty Russell07ad1572007-07-19 01:49:22 -0700478static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
479 pte_t *ptep, pte_t pteval)
480{
481 *ptep = pteval;
482 lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low);
483}
484
Rusty Russellb2b47c22007-07-26 10:41:02 -0700485/* The Guest calls this to set a top-level entry. Again, we set the entry then
486 * tell the Host which top-level page we changed, and the index of the entry we
487 * changed. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700488static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
489{
490 *pmdp = pmdval;
491 lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK,
Rusty Russell4357bd92008-03-11 09:35:57 -0500492 (__pa(pmdp)&(PAGE_SIZE-1))/4, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700493}
494
Rusty Russellb2b47c22007-07-26 10:41:02 -0700495/* There are a couple of legacy places where the kernel sets a PTE, but we
496 * don't know the top level any more. This is useless for us, since we don't
497 * know which pagetable is changing or what address, so we just tell the Host
498 * to forget all of them. Fortunately, this is very rare.
499 *
500 * ... except in early boot when the kernel sets up the initial pagetables,
501 * which makes booting astonishingly slow. So we don't even tell the Host
Rusty Russelle1e72962007-10-25 15:02:50 +1000502 * anything changed until we've done the first page table switch. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700503static void lguest_set_pte(pte_t *ptep, pte_t pteval)
504{
505 *ptep = pteval;
506 /* Don't bother with hypercall before initial setup. */
507 if (current_cr3)
508 lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
509}
510
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700511/* Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
Rusty Russellb2b47c22007-07-26 10:41:02 -0700512 * native page table operations. On native hardware you can set a new page
513 * table entry whenever you want, but if you want to remove one you have to do
514 * a TLB flush (a TLB is a little cache of page table entries kept by the CPU).
515 *
516 * So the lguest_set_pte_at() and lguest_set_pmd() functions above are only
517 * called when a valid entry is written, not when it's removed (ie. marked not
518 * present). Instead, this is where we come when the Guest wants to remove a
519 * page table entry: we tell the Host to set that entry to 0 (ie. the present
520 * bit is zero). */
Rusty Russell07ad1572007-07-19 01:49:22 -0700521static void lguest_flush_tlb_single(unsigned long addr)
522{
Rusty Russellb2b47c22007-07-26 10:41:02 -0700523 /* Simply set it to zero: if it was not, it will fault back in. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700524 lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
525}
526
Rusty Russellb2b47c22007-07-26 10:41:02 -0700527/* This is what happens after the Guest has removed a large number of entries.
528 * This tells the Host that any of the page table entries for userspace might
529 * have changed, ie. virtual addresses below PAGE_OFFSET. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700530static void lguest_flush_tlb_user(void)
531{
532 lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
533}
534
Rusty Russellb2b47c22007-07-26 10:41:02 -0700535/* This is called when the kernel page tables have changed. That's not very
536 * common (unless the Guest is using highmem, which makes the Guest extremely
537 * slow), so it's worth separating this from the user flushing above. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700538static void lguest_flush_tlb_kernel(void)
539{
540 lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
541}
542
Rusty Russellb2b47c22007-07-26 10:41:02 -0700543/*
544 * The Unadvanced Programmable Interrupt Controller.
545 *
546 * This is an attempt to implement the simplest possible interrupt controller.
547 * I spent some time looking though routines like set_irq_chip_and_handler,
548 * set_irq_chip_and_handler_name, set_irq_chip_data and set_phasers_to_stun and
549 * I *think* this is as simple as it gets.
550 *
551 * We can tell the Host what interrupts we want blocked ready for using the
552 * lguest_data.interrupts bitmap, so disabling (aka "masking") them is as
553 * simple as setting a bit. We don't actually "ack" interrupts as such, we
554 * just mask and unmask them. I wonder if we should be cleverer?
555 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700556static void disable_lguest_irq(unsigned int irq)
557{
558 set_bit(irq, lguest_data.blocked_interrupts);
559}
560
561static void enable_lguest_irq(unsigned int irq)
562{
563 clear_bit(irq, lguest_data.blocked_interrupts);
Rusty Russell07ad1572007-07-19 01:49:22 -0700564}
565
Rusty Russellb2b47c22007-07-26 10:41:02 -0700566/* This structure describes the lguest IRQ controller. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700567static struct irq_chip lguest_irq_controller = {
568 .name = "lguest",
569 .mask = disable_lguest_irq,
570 .mask_ack = disable_lguest_irq,
571 .unmask = enable_lguest_irq,
572};
573
Rusty Russellb2b47c22007-07-26 10:41:02 -0700574/* This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
575 * interrupt (except 128, which is used for system calls), and then tells the
576 * Linux infrastructure that each interrupt is controlled by our level-based
577 * lguest interrupt controller. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700578static void __init lguest_init_IRQ(void)
579{
580 unsigned int i;
581
582 for (i = 0; i < LGUEST_IRQS; i++) {
583 int vector = FIRST_EXTERNAL_VECTOR + i;
584 if (vector != SYSCALL_VECTOR) {
Yinghai Lu497c9a12008-08-19 20:50:28 -0700585 set_intr_gate(vector, interrupt[vector]);
Rusty Russella16ffe92008-05-30 15:09:42 -0500586 set_irq_chip_and_handler_name(i, &lguest_irq_controller,
587 handle_level_irq,
588 "level");
Rusty Russell07ad1572007-07-19 01:49:22 -0700589 }
590 }
Rusty Russellb2b47c22007-07-26 10:41:02 -0700591 /* This call is required to set up for 4k stacks, where we have
592 * separate stacks for hard and soft interrupts. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700593 irq_ctx_init(smp_processor_id());
594}
595
Rusty Russellb2b47c22007-07-26 10:41:02 -0700596/*
597 * Time.
598 *
599 * It would be far better for everyone if the Guest had its own clock, but
Rusty Russell6c8dca52007-07-27 13:42:52 +1000600 * until then the Host gives us the time on every interrupt.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700601 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700602static unsigned long lguest_get_wallclock(void)
603{
Rusty Russell6c8dca52007-07-27 13:42:52 +1000604 return lguest_data.time.tv_sec;
Rusty Russell07ad1572007-07-19 01:49:22 -0700605}
606
Rusty Russella6bd8e12008-03-28 11:05:53 -0500607/* The TSC is an Intel thing called the Time Stamp Counter. The Host tells us
608 * what speed it runs at, or 0 if it's unusable as a reliable clock source.
609 * This matches what we want here: if we return 0 from this function, the x86
610 * TSC clock will give up and not register itself. */
Alok Katariae93ef942008-07-01 11:43:36 -0700611static unsigned long lguest_tsc_khz(void)
Rusty Russell3fabc552008-03-11 09:35:56 -0500612{
613 return lguest_data.tsc_khz;
614}
615
Rusty Russella6bd8e12008-03-28 11:05:53 -0500616/* If we can't use the TSC, the kernel falls back to our lower-priority
617 * "lguest_clock", where we read the time value given to us by the Host. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700618static cycle_t lguest_clock_read(void)
Rusty Russell07ad1572007-07-19 01:49:22 -0700619{
Rusty Russell6c8dca52007-07-27 13:42:52 +1000620 unsigned long sec, nsec;
621
Rusty Russell3fabc552008-03-11 09:35:56 -0500622 /* Since the time is in two parts (seconds and nanoseconds), we risk
623 * reading it just as it's changing from 99 & 0.999999999 to 100 and 0,
624 * and getting 99 and 0. As Linux tends to come apart under the stress
625 * of time travel, we must be careful: */
Rusty Russell6c8dca52007-07-27 13:42:52 +1000626 do {
627 /* First we read the seconds part. */
628 sec = lguest_data.time.tv_sec;
629 /* This read memory barrier tells the compiler and the CPU that
630 * this can't be reordered: we have to complete the above
631 * before going on. */
632 rmb();
633 /* Now we read the nanoseconds part. */
634 nsec = lguest_data.time.tv_nsec;
635 /* Make sure we've done that. */
636 rmb();
637 /* Now if the seconds part has changed, try again. */
638 } while (unlikely(lguest_data.time.tv_sec != sec));
639
Rusty Russell3fabc552008-03-11 09:35:56 -0500640 /* Our lguest clock is in real nanoseconds. */
Rusty Russell6c8dca52007-07-27 13:42:52 +1000641 return sec*1000000000ULL + nsec;
Rusty Russell07ad1572007-07-19 01:49:22 -0700642}
643
Rusty Russell3fabc552008-03-11 09:35:56 -0500644/* This is the fallback clocksource: lower priority than the TSC clocksource. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700645static struct clocksource lguest_clock = {
646 .name = "lguest",
Rusty Russell3fabc552008-03-11 09:35:56 -0500647 .rating = 200,
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700648 .read = lguest_clock_read,
Rusty Russell6c8dca52007-07-27 13:42:52 +1000649 .mask = CLOCKSOURCE_MASK(64),
Rusty Russell37250092007-08-09 20:52:35 +1000650 .mult = 1 << 22,
651 .shift = 22,
Tony Breeds05aa0262007-10-22 10:56:25 +1000652 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700653};
654
655/* We also need a "struct clock_event_device": Linux asks us to set it to go
656 * off some time in the future. Actually, James Morris figured all this out, I
657 * just applied the patch. */
658static int lguest_clockevent_set_next_event(unsigned long delta,
659 struct clock_event_device *evt)
660{
Rusty Russella6bd8e12008-03-28 11:05:53 -0500661 /* FIXME: I don't think this can ever happen, but James tells me he had
662 * to put this code in. Maybe we should remove it now. Anyone? */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700663 if (delta < LG_CLOCK_MIN_DELTA) {
664 if (printk_ratelimit())
665 printk(KERN_DEBUG "%s: small delta %lu ns\n",
Harvey Harrison77bf90e2008-03-03 11:37:23 -0800666 __func__, delta);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700667 return -ETIME;
668 }
Rusty Russella6bd8e12008-03-28 11:05:53 -0500669
670 /* Please wake us this far in the future. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700671 hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
672 return 0;
673}
674
675static void lguest_clockevent_set_mode(enum clock_event_mode mode,
676 struct clock_event_device *evt)
677{
678 switch (mode) {
679 case CLOCK_EVT_MODE_UNUSED:
680 case CLOCK_EVT_MODE_SHUTDOWN:
681 /* A 0 argument shuts the clock down. */
682 hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
683 break;
684 case CLOCK_EVT_MODE_ONESHOT:
685 /* This is what we expect. */
686 break;
687 case CLOCK_EVT_MODE_PERIODIC:
688 BUG();
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700689 case CLOCK_EVT_MODE_RESUME:
690 break;
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700691 }
692}
693
694/* This describes our primitive timer chip. */
695static struct clock_event_device lguest_clockevent = {
696 .name = "lguest",
697 .features = CLOCK_EVT_FEAT_ONESHOT,
698 .set_next_event = lguest_clockevent_set_next_event,
699 .set_mode = lguest_clockevent_set_mode,
700 .rating = INT_MAX,
701 .mult = 1,
702 .shift = 0,
703 .min_delta_ns = LG_CLOCK_MIN_DELTA,
704 .max_delta_ns = LG_CLOCK_MAX_DELTA,
705};
706
707/* This is the Guest timer interrupt handler (hardware interrupt 0). We just
708 * call the clockevent infrastructure and it does whatever needs doing. */
709static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
710{
711 unsigned long flags;
712
713 /* Don't interrupt us while this is running. */
714 local_irq_save(flags);
715 lguest_clockevent.event_handler(&lguest_clockevent);
716 local_irq_restore(flags);
717}
718
Rusty Russellb2b47c22007-07-26 10:41:02 -0700719/* At some point in the boot process, we get asked to set up our timing
720 * infrastructure. The kernel doesn't expect timer interrupts before this, but
721 * we cleverly initialized the "blocked_interrupts" field of "struct
722 * lguest_data" so that timer interrupts were blocked until now. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700723static void lguest_time_init(void)
724{
Rusty Russellb2b47c22007-07-26 10:41:02 -0700725 /* Set up the timer interrupt (0) to go to our simple timer routine */
Rusty Russell07ad1572007-07-19 01:49:22 -0700726 set_irq_handler(0, lguest_time_irq);
Rusty Russell07ad1572007-07-19 01:49:22 -0700727
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700728 clocksource_register(&lguest_clock);
729
Rusty Russellb2b47c22007-07-26 10:41:02 -0700730 /* We can't set cpumask in the initializer: damn C limitations! Set it
731 * here and register our timer device. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700732 lguest_clockevent.cpumask = cpumask_of_cpu(0);
733 clockevents_register_device(&lguest_clockevent);
734
Rusty Russellb2b47c22007-07-26 10:41:02 -0700735 /* Finally, we unblock the timer interrupt. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700736 enable_lguest_irq(0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700737}
738
Rusty Russellb2b47c22007-07-26 10:41:02 -0700739/*
740 * Miscellaneous bits and pieces.
741 *
742 * Here is an oddball collection of functions which the Guest needs for things
743 * to work. They're pretty simple.
744 */
745
Rusty Russelle1e72962007-10-25 15:02:50 +1000746/* The Guest needs to tell the Host what stack it expects traps to use. For
Rusty Russellb2b47c22007-07-26 10:41:02 -0700747 * native hardware, this is part of the Task State Segment mentioned above in
748 * lguest_load_tr_desc(), but to help hypervisors there's this special call.
749 *
750 * We tell the Host the segment we want to use (__KERNEL_DS is the kernel data
751 * segment), the privilege level (we're privilege level 1, the Host is 0 and
752 * will not tolerate us trying to use that), the stack pointer, and the number
753 * of pages in the stack. */
H. Peter Anvinfaca6222008-01-30 13:31:02 +0100754static void lguest_load_sp0(struct tss_struct *tss,
Rusty Russella6bd8e12008-03-28 11:05:53 -0500755 struct thread_struct *thread)
Rusty Russell07ad1572007-07-19 01:49:22 -0700756{
H. Peter Anvinfaca6222008-01-30 13:31:02 +0100757 lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->sp0,
Rusty Russell07ad1572007-07-19 01:49:22 -0700758 THREAD_SIZE/PAGE_SIZE);
759}
760
Rusty Russellb2b47c22007-07-26 10:41:02 -0700761/* Let's just say, I wouldn't do debugging under a Guest. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700762static void lguest_set_debugreg(int regno, unsigned long value)
763{
764 /* FIXME: Implement */
765}
766
Rusty Russellb2b47c22007-07-26 10:41:02 -0700767/* There are times when the kernel wants to make sure that no memory writes are
768 * caught in the cache (that they've all reached real hardware devices). This
769 * doesn't matter for the Guest which has virtual hardware.
770 *
771 * On the Pentium 4 and above, cpuid() indicates that the Cache Line Flush
772 * (clflush) instruction is available and the kernel uses that. Otherwise, it
773 * uses the older "Write Back and Invalidate Cache" (wbinvd) instruction.
774 * Unlike clflush, wbinvd can only be run at privilege level 0. So we can
775 * ignore clflush, but replace wbinvd.
776 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700777static void lguest_wbinvd(void)
778{
779}
780
Rusty Russellb2b47c22007-07-26 10:41:02 -0700781/* If the Guest expects to have an Advanced Programmable Interrupt Controller,
782 * we play dumb by ignoring writes and returning 0 for reads. So it's no
783 * longer Programmable nor Controlling anything, and I don't think 8 lines of
784 * code qualifies for Advanced. It will also never interrupt anything. It
785 * does, however, allow us to get through the Linux boot code. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700786#ifdef CONFIG_X86_LOCAL_APIC
Suresh Siddhaad66dd32008-07-11 13:11:56 -0700787static void lguest_apic_write(u32 reg, u32 v)
Rusty Russell07ad1572007-07-19 01:49:22 -0700788{
789}
790
Suresh Siddhaad66dd32008-07-11 13:11:56 -0700791static u32 lguest_apic_read(u32 reg)
Rusty Russell07ad1572007-07-19 01:49:22 -0700792{
793 return 0;
794}
Suresh Siddha511d9d32008-07-14 09:49:14 -0700795
796static u64 lguest_apic_icr_read(void)
797{
798 return 0;
799}
800
801static void lguest_apic_icr_write(u32 low, u32 id)
802{
803 /* Warn to see if there's any stray references */
804 WARN_ON(1);
805}
806
807static void lguest_apic_wait_icr_idle(void)
808{
809 return;
810}
811
812static u32 lguest_apic_safe_wait_icr_idle(void)
813{
814 return 0;
815}
816
817static struct apic_ops lguest_basic_apic_ops = {
818 .read = lguest_apic_read,
819 .write = lguest_apic_write,
Suresh Siddha511d9d32008-07-14 09:49:14 -0700820 .icr_read = lguest_apic_icr_read,
821 .icr_write = lguest_apic_icr_write,
822 .wait_icr_idle = lguest_apic_wait_icr_idle,
823 .safe_wait_icr_idle = lguest_apic_safe_wait_icr_idle,
824};
Rusty Russell07ad1572007-07-19 01:49:22 -0700825#endif
826
Rusty Russellb2b47c22007-07-26 10:41:02 -0700827/* STOP! Until an interrupt comes in. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700828static void lguest_safe_halt(void)
829{
830 hcall(LHCALL_HALT, 0, 0, 0);
831}
832
Rusty Russella6bd8e12008-03-28 11:05:53 -0500833/* The SHUTDOWN hypercall takes a string to describe what's happening, and
834 * an argument which says whether this to restart (reboot) the Guest or not.
Rusty Russellb2b47c22007-07-26 10:41:02 -0700835 *
836 * Note that the Host always prefers that the Guest speak in physical addresses
837 * rather than virtual addresses, so we use __pa() here. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700838static void lguest_power_off(void)
839{
Balaji Raoec04b132007-12-28 14:26:24 +0530840 hcall(LHCALL_SHUTDOWN, __pa("Power down"), LGUEST_SHUTDOWN_POWEROFF, 0);
Rusty Russell07ad1572007-07-19 01:49:22 -0700841}
842
Rusty Russellb2b47c22007-07-26 10:41:02 -0700843/*
844 * Panicing.
845 *
846 * Don't. But if you did, this is what happens.
847 */
Rusty Russell07ad1572007-07-19 01:49:22 -0700848static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
849{
Balaji Raoec04b132007-12-28 14:26:24 +0530850 hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0);
Rusty Russellb2b47c22007-07-26 10:41:02 -0700851 /* The hcall won't return, but to keep gcc happy, we're "done". */
Rusty Russell07ad1572007-07-19 01:49:22 -0700852 return NOTIFY_DONE;
853}
854
855static struct notifier_block paniced = {
856 .notifier_call = lguest_panic
857};
858
Rusty Russellb2b47c22007-07-26 10:41:02 -0700859/* Setting up memory is fairly easy. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700860static __init char *lguest_memory_setup(void)
861{
Rusty Russella6bd8e12008-03-28 11:05:53 -0500862 /* We do this here and not earlier because lockcheck used to barf if we
863 * did it before start_kernel(). I think we fixed that, so it'd be
864 * nice to move it back to lguest_init. Patch welcome... */
Rusty Russell07ad1572007-07-19 01:49:22 -0700865 atomic_notifier_chain_register(&panic_notifier_list, &paniced);
866
Rusty Russellb2b47c22007-07-26 10:41:02 -0700867 /* The Linux bootloader header contains an "e820" memory map: the
868 * Launcher populated the first entry with our memory limit. */
Yinghai Lud0be6bd2008-06-15 18:58:51 -0700869 e820_add_region(boot_params.e820_map[0].addr,
H. Peter Anvin30c82642007-10-15 17:13:22 -0700870 boot_params.e820_map[0].size,
871 boot_params.e820_map[0].type);
Rusty Russellb2b47c22007-07-26 10:41:02 -0700872
873 /* This string is for the boot messages. */
Rusty Russell07ad1572007-07-19 01:49:22 -0700874 return "LGUEST";
875}
876
Rusty Russelle1e72962007-10-25 15:02:50 +1000877/* We will eventually use the virtio console device to produce console output,
878 * but before that is set up we use LHCALL_NOTIFY on normal memory to produce
879 * console output. */
Rusty Russell19f15372007-10-22 11:24:21 +1000880static __init int early_put_chars(u32 vtermno, const char *buf, int count)
881{
882 char scratch[17];
883 unsigned int len = count;
884
Rusty Russelle1e72962007-10-25 15:02:50 +1000885 /* We use a nul-terminated string, so we have to make a copy. Icky,
886 * huh? */
Rusty Russell19f15372007-10-22 11:24:21 +1000887 if (len > sizeof(scratch) - 1)
888 len = sizeof(scratch) - 1;
889 scratch[len] = '\0';
890 memcpy(scratch, buf, len);
891 hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0);
892
893 /* This routine returns the number of bytes actually written. */
894 return len;
895}
896
Rusty Russella6bd8e12008-03-28 11:05:53 -0500897/* Rebooting also tells the Host we're finished, but the RESTART flag tells the
898 * Launcher to reboot us. */
899static void lguest_restart(char *reason)
900{
901 hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0);
902}
903
Rusty Russellb2b47c22007-07-26 10:41:02 -0700904/*G:050
905 * Patching (Powerfully Placating Performance Pedants)
906 *
Rusty Russella6bd8e12008-03-28 11:05:53 -0500907 * We have already seen that pv_ops structures let us replace simple native
908 * instructions with calls to the appropriate back end all throughout the
909 * kernel. This allows the same kernel to run as a Guest and as a native
Rusty Russellb2b47c22007-07-26 10:41:02 -0700910 * kernel, but it's slow because of all the indirect branches.
911 *
912 * Remember that David Wheeler quote about "Any problem in computer science can
913 * be solved with another layer of indirection"? The rest of that quote is
914 * "... But that usually will create another problem." This is the first of
915 * those problems.
916 *
917 * Our current solution is to allow the paravirt back end to optionally patch
918 * over the indirect calls to replace them with something more efficient. We
919 * patch the four most commonly called functions: disable interrupts, enable
Rusty Russelle1e72962007-10-25 15:02:50 +1000920 * interrupts, restore interrupts and save interrupts. We usually have 6 or 10
Rusty Russellb2b47c22007-07-26 10:41:02 -0700921 * bytes to patch into: the Guest versions of these operations are small enough
922 * that we can fit comfortably.
923 *
924 * First we need assembly templates of each of the patchable Guest operations,
925 * and these are in lguest_asm.S. */
926
927/*G:060 We construct a table from the assembler templates: */
Rusty Russell07ad1572007-07-19 01:49:22 -0700928static const struct lguest_insns
929{
930 const char *start, *end;
931} lguest_insns[] = {
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700932 [PARAVIRT_PATCH(pv_irq_ops.irq_disable)] = { lgstart_cli, lgend_cli },
933 [PARAVIRT_PATCH(pv_irq_ops.irq_enable)] = { lgstart_sti, lgend_sti },
934 [PARAVIRT_PATCH(pv_irq_ops.restore_fl)] = { lgstart_popf, lgend_popf },
935 [PARAVIRT_PATCH(pv_irq_ops.save_fl)] = { lgstart_pushf, lgend_pushf },
Rusty Russell07ad1572007-07-19 01:49:22 -0700936};
Rusty Russellb2b47c22007-07-26 10:41:02 -0700937
938/* Now our patch routine is fairly simple (based on the native one in
939 * paravirt.c). If we have a replacement, we copy it in and return how much of
940 * the available space we used. */
Andi Kleenab144f52007-08-10 22:31:03 +0200941static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf,
942 unsigned long addr, unsigned len)
Rusty Russell07ad1572007-07-19 01:49:22 -0700943{
944 unsigned int insn_len;
945
Rusty Russellb2b47c22007-07-26 10:41:02 -0700946 /* Don't do anything special if we don't have a replacement */
Rusty Russell07ad1572007-07-19 01:49:22 -0700947 if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
Andi Kleenab144f52007-08-10 22:31:03 +0200948 return paravirt_patch_default(type, clobber, ibuf, addr, len);
Rusty Russell07ad1572007-07-19 01:49:22 -0700949
950 insn_len = lguest_insns[type].end - lguest_insns[type].start;
951
Rusty Russellb2b47c22007-07-26 10:41:02 -0700952 /* Similarly if we can't fit replacement (shouldn't happen, but let's
953 * be thorough). */
Rusty Russell07ad1572007-07-19 01:49:22 -0700954 if (len < insn_len)
Andi Kleenab144f52007-08-10 22:31:03 +0200955 return paravirt_patch_default(type, clobber, ibuf, addr, len);
Rusty Russell07ad1572007-07-19 01:49:22 -0700956
Rusty Russellb2b47c22007-07-26 10:41:02 -0700957 /* Copy in our instructions. */
Andi Kleenab144f52007-08-10 22:31:03 +0200958 memcpy(ibuf, lguest_insns[type].start, insn_len);
Rusty Russell07ad1572007-07-19 01:49:22 -0700959 return insn_len;
960}
961
Rusty Russella6bd8e12008-03-28 11:05:53 -0500962/*G:030 Once we get to lguest_init(), we know we're a Guest. The various
963 * pv_ops structures in the kernel provide points for (almost) every routine we
964 * have to override to avoid privileged instructions. */
Rusty Russell814a0e52007-10-22 11:29:44 +1000965__init void lguest_init(void)
Rusty Russell07ad1572007-07-19 01:49:22 -0700966{
Rusty Russellb2b47c22007-07-26 10:41:02 -0700967 /* We're under lguest, paravirt is enabled, and we're running at
968 * privilege level 1, not 0 as normal. */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700969 pv_info.name = "lguest";
970 pv_info.paravirt_enabled = 1;
971 pv_info.kernel_rpl = 1;
Rusty Russell07ad1572007-07-19 01:49:22 -0700972
Rusty Russellb2b47c22007-07-26 10:41:02 -0700973 /* We set up all the lguest overrides for sensitive operations. These
974 * are detailed with the operations themselves. */
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700975
976 /* interrupt-related operations */
977 pv_irq_ops.init_IRQ = lguest_init_IRQ;
978 pv_irq_ops.save_fl = save_fl;
979 pv_irq_ops.restore_fl = restore_fl;
980 pv_irq_ops.irq_disable = irq_disable;
981 pv_irq_ops.irq_enable = irq_enable;
982 pv_irq_ops.safe_halt = lguest_safe_halt;
983
984 /* init-time operations */
985 pv_init_ops.memory_setup = lguest_memory_setup;
986 pv_init_ops.patch = lguest_patch;
987
988 /* Intercepts of various cpu instructions */
989 pv_cpu_ops.load_gdt = lguest_load_gdt;
990 pv_cpu_ops.cpuid = lguest_cpuid;
991 pv_cpu_ops.load_idt = lguest_load_idt;
992 pv_cpu_ops.iret = lguest_iret;
H. Peter Anvinfaca6222008-01-30 13:31:02 +0100993 pv_cpu_ops.load_sp0 = lguest_load_sp0;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -0700994 pv_cpu_ops.load_tr_desc = lguest_load_tr_desc;
995 pv_cpu_ops.set_ldt = lguest_set_ldt;
996 pv_cpu_ops.load_tls = lguest_load_tls;
997 pv_cpu_ops.set_debugreg = lguest_set_debugreg;
998 pv_cpu_ops.clts = lguest_clts;
999 pv_cpu_ops.read_cr0 = lguest_read_cr0;
1000 pv_cpu_ops.write_cr0 = lguest_write_cr0;
1001 pv_cpu_ops.read_cr4 = lguest_read_cr4;
1002 pv_cpu_ops.write_cr4 = lguest_write_cr4;
1003 pv_cpu_ops.write_gdt_entry = lguest_write_gdt_entry;
1004 pv_cpu_ops.write_idt_entry = lguest_write_idt_entry;
1005 pv_cpu_ops.wbinvd = lguest_wbinvd;
Jeremy Fitzhardinge8965c1c2007-10-16 11:51:29 -07001006 pv_cpu_ops.lazy_mode.enter = paravirt_enter_lazy_cpu;
1007 pv_cpu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001008
1009 /* pagetable management */
1010 pv_mmu_ops.write_cr3 = lguest_write_cr3;
1011 pv_mmu_ops.flush_tlb_user = lguest_flush_tlb_user;
1012 pv_mmu_ops.flush_tlb_single = lguest_flush_tlb_single;
1013 pv_mmu_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
1014 pv_mmu_ops.set_pte = lguest_set_pte;
1015 pv_mmu_ops.set_pte_at = lguest_set_pte_at;
1016 pv_mmu_ops.set_pmd = lguest_set_pmd;
1017 pv_mmu_ops.read_cr2 = lguest_read_cr2;
1018 pv_mmu_ops.read_cr3 = lguest_read_cr3;
Jeremy Fitzhardinge8965c1c2007-10-16 11:51:29 -07001019 pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
1020 pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001021
Rusty Russell07ad1572007-07-19 01:49:22 -07001022#ifdef CONFIG_X86_LOCAL_APIC
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001023 /* apic read/write intercepts */
Suresh Siddha511d9d32008-07-14 09:49:14 -07001024 apic_ops = &lguest_basic_apic_ops;
Rusty Russell07ad1572007-07-19 01:49:22 -07001025#endif
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001026
1027 /* time operations */
1028 pv_time_ops.get_wallclock = lguest_get_wallclock;
1029 pv_time_ops.time_init = lguest_time_init;
Alok Katariae93ef942008-07-01 11:43:36 -07001030 pv_time_ops.get_tsc_khz = lguest_tsc_khz;
Jeremy Fitzhardinge93b1eab2007-10-16 11:51:29 -07001031
Rusty Russellb2b47c22007-07-26 10:41:02 -07001032 /* Now is a good time to look at the implementations of these functions
1033 * before returning to the rest of lguest_init(). */
Rusty Russell07ad1572007-07-19 01:49:22 -07001034
Rusty Russellb2b47c22007-07-26 10:41:02 -07001035 /*G:070 Now we've seen all the paravirt_ops, we return to
1036 * lguest_init() where the rest of the fairly chaotic boot setup
Rusty Russell47436aa2007-10-22 11:03:36 +10001037 * occurs. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001038
Rusty Russellb2b47c22007-07-26 10:41:02 -07001039 /* The native boot code sets up initial page tables immediately after
1040 * the kernel itself, and sets init_pg_tables_end so they're not
1041 * clobbered. The Launcher places our initial pagetables somewhere at
1042 * the top of our physical memory, so we don't need extra space: set
1043 * init_pg_tables_end to the end of the kernel. */
Yinghai Luf0d43102008-05-29 12:56:36 -07001044 init_pg_tables_start = __pa(pg0);
Rusty Russell07ad1572007-07-19 01:49:22 -07001045 init_pg_tables_end = __pa(pg0);
1046
Rusty Russell5d006d82008-07-29 09:58:29 -05001047 /* As described in head_32.S, we map the first 128M of memory. */
1048 max_pfn_mapped = (128*1024*1024) >> PAGE_SHIFT;
1049
Rusty Russellb2b47c22007-07-26 10:41:02 -07001050 /* Load the %fs segment register (the per-cpu segment register) with
1051 * the normal data segment to get through booting. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001052 asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
1053
Rusty Russella6bd8e12008-03-28 11:05:53 -05001054 /* The Host<->Guest Switcher lives at the top of our address space, and
1055 * the Host told us how big it is when we made LGUEST_INIT hypercall:
1056 * it put the answer in lguest_data.reserve_mem */
Rusty Russell07ad1572007-07-19 01:49:22 -07001057 reserve_top_address(lguest_data.reserve_mem);
1058
Rusty Russellb2b47c22007-07-26 10:41:02 -07001059 /* If we don't initialize the lock dependency checker now, it crashes
1060 * paravirt_disable_iospace. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001061 lockdep_init();
1062
Rusty Russellb2b47c22007-07-26 10:41:02 -07001063 /* The IDE code spends about 3 seconds probing for disks: if we reserve
1064 * all the I/O ports up front it can't get them and so doesn't probe.
1065 * Other device drivers are similar (but less severe). This cuts the
1066 * kernel boot time on my machine from 4.1 seconds to 0.45 seconds. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001067 paravirt_disable_iospace();
1068
Rusty Russellb2b47c22007-07-26 10:41:02 -07001069 /* This is messy CPU setup stuff which the native boot code does before
1070 * start_kernel, so we have to do, too: */
Rusty Russell07ad1572007-07-19 01:49:22 -07001071 cpu_detect(&new_cpu_data);
1072 /* head.S usually sets up the first capability word, so do it here. */
1073 new_cpu_data.x86_capability[0] = cpuid_edx(1);
1074
1075 /* Math is always hard! */
1076 new_cpu_data.hard_math = 1;
1077
Rusty Russella6bd8e12008-03-28 11:05:53 -05001078 /* We don't have features. We have puppies! Puppies! */
Rusty Russell07ad1572007-07-19 01:49:22 -07001079#ifdef CONFIG_X86_MCE
1080 mce_disabled = 1;
1081#endif
Rusty Russell07ad1572007-07-19 01:49:22 -07001082#ifdef CONFIG_ACPI
1083 acpi_disabled = 1;
1084 acpi_ht = 0;
1085#endif
1086
Rusty Russellb2b47c22007-07-26 10:41:02 -07001087 /* We set the perferred console to "hvc". This is the "hypervisor
1088 * virtual console" driver written by the PowerPC people, which we also
1089 * adapted for lguest's use. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001090 add_preferred_console("hvc", 0, NULL);
1091
Rusty Russell19f15372007-10-22 11:24:21 +10001092 /* Register our very early console. */
1093 virtio_cons_early_init(early_put_chars);
1094
Rusty Russellb2b47c22007-07-26 10:41:02 -07001095 /* Last of all, we set the power management poweroff hook to point to
Rusty Russella6bd8e12008-03-28 11:05:53 -05001096 * the Guest routine to power off, and the reboot hook to our restart
1097 * routine. */
Rusty Russell07ad1572007-07-19 01:49:22 -07001098 pm_power_off = lguest_power_off;
Balaji Raoec04b132007-12-28 14:26:24 +05301099 machine_ops.restart = lguest_restart;
Rusty Russella6bd8e12008-03-28 11:05:53 -05001100
Yinghai Luf0d43102008-05-29 12:56:36 -07001101 /* Now we're set up, call i386_start_kernel() in head32.c and we proceed
Rusty Russellb2b47c22007-07-26 10:41:02 -07001102 * to boot as normal. It never returns. */
Yinghai Luf0d43102008-05-29 12:56:36 -07001103 i386_start_kernel();
Rusty Russell07ad1572007-07-19 01:49:22 -07001104}
Rusty Russellb2b47c22007-07-26 10:41:02 -07001105/*
1106 * This marks the end of stage II of our journey, The Guest.
1107 *
Rusty Russelle1e72962007-10-25 15:02:50 +10001108 * It is now time for us to explore the layer of virtual drivers and complete
1109 * our understanding of the Guest in "make Drivers".
Rusty Russellb2b47c22007-07-26 10:41:02 -07001110 */