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Rusty Russellf938d2c2007-07-26 10:41:02 -07001/*P:500 Just as userspace programs request kernel operations through a system
2 * call, the Guest requests Host operations through a "hypercall". You might
3 * notice this nomenclature doesn't really follow any logic, but the name has
4 * been around for long enough that we're stuck with it. As you'd expect, this
5 * code is basically a one big switch statement. :*/
6
7/* Copyright (C) 2006 Rusty Russell IBM Corporation
Rusty Russelld7e28ff2007-07-19 01:49:23 -07008
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22*/
23#include <linux/uaccess.h>
24#include <linux/syscalls.h>
25#include <linux/mm.h>
26#include <asm/page.h>
27#include <asm/pgtable.h>
28#include <irq_vectors.h>
29#include "lg.h"
30
Rusty Russellbff672e2007-07-26 10:41:04 -070031/*H:120 This is the core hypercall routine: where the Guest gets what it
32 * wants. Or gets killed. Or, in the case of LHCALL_CRASH, both.
33 *
34 * Remember from the Guest: %eax == which call to make, and the arguments are
35 * packed into %edx, %ebx and %ecx if needed. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070036static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
37{
38 switch (regs->eax) {
39 case LHCALL_FLUSH_ASYNC:
Rusty Russellbff672e2007-07-26 10:41:04 -070040 /* This call does nothing, except by breaking out of the Guest
41 * it makes us process all the asynchronous hypercalls. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070042 break;
43 case LHCALL_LGUEST_INIT:
Rusty Russellbff672e2007-07-26 10:41:04 -070044 /* You can't get here unless you're already initialized. Don't
45 * do that. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070046 kill_guest(lg, "already have lguest_data");
47 break;
48 case LHCALL_CRASH: {
Rusty Russellbff672e2007-07-26 10:41:04 -070049 /* Crash is such a trivial hypercall that we do it in four
50 * lines right here. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070051 char msg[128];
Rusty Russellbff672e2007-07-26 10:41:04 -070052 /* If the lgread fails, it will call kill_guest() itself; the
53 * kill_guest() with the message will be ignored. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070054 lgread(lg, msg, regs->edx, sizeof(msg));
55 msg[sizeof(msg)-1] = '\0';
56 kill_guest(lg, "CRASH: %s", msg);
57 break;
58 }
59 case LHCALL_FLUSH_TLB:
Rusty Russellbff672e2007-07-26 10:41:04 -070060 /* FLUSH_TLB comes in two flavors, depending on the
61 * argument: */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070062 if (regs->edx)
63 guest_pagetable_clear_all(lg);
64 else
65 guest_pagetable_flush_user(lg);
66 break;
Rusty Russelld7e28ff2007-07-19 01:49:23 -070067 case LHCALL_BIND_DMA:
Rusty Russellbff672e2007-07-26 10:41:04 -070068 /* BIND_DMA really wants four arguments, but it's the only call
69 * which does. So the Guest packs the number of buffers and
70 * the interrupt number into the final argument, and we decode
71 * it here. This can legitimately fail, since we currently
72 * place a limit on the number of DMA pools a Guest can have.
73 * So we return true or false from this call. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070074 regs->eax = bind_dma(lg, regs->edx, regs->ebx,
75 regs->ecx >> 8, regs->ecx & 0xFF);
76 break;
Rusty Russellbff672e2007-07-26 10:41:04 -070077
78 /* All these calls simply pass the arguments through to the right
79 * routines. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070080 case LHCALL_SEND_DMA:
81 send_dma(lg, regs->edx, regs->ebx);
82 break;
83 case LHCALL_LOAD_GDT:
84 load_guest_gdt(lg, regs->edx, regs->ebx);
85 break;
86 case LHCALL_LOAD_IDT_ENTRY:
87 load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
88 break;
89 case LHCALL_NEW_PGTABLE:
90 guest_new_pagetable(lg, regs->edx);
91 break;
92 case LHCALL_SET_STACK:
93 guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
94 break;
95 case LHCALL_SET_PTE:
96 guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
97 break;
98 case LHCALL_SET_PMD:
99 guest_set_pmd(lg, regs->edx, regs->ebx);
100 break;
101 case LHCALL_LOAD_TLS:
102 guest_load_tls(lg, regs->edx);
103 break;
104 case LHCALL_SET_CLOCKEVENT:
105 guest_set_clockevent(lg, regs->edx);
106 break;
Rusty Russellbff672e2007-07-26 10:41:04 -0700107
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700108 case LHCALL_TS:
Rusty Russellbff672e2007-07-26 10:41:04 -0700109 /* This sets the TS flag, as we saw used in run_guest(). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700110 lg->ts = regs->edx;
111 break;
112 case LHCALL_HALT:
Rusty Russellbff672e2007-07-26 10:41:04 -0700113 /* Similarly, this sets the halted flag for run_guest(). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700114 lg->halted = 1;
115 break;
116 default:
117 kill_guest(lg, "Bad hypercall %li\n", regs->eax);
118 }
119}
120
Rusty Russellbff672e2007-07-26 10:41:04 -0700121/* Asynchronous hypercalls are easy: we just look in the array in the Guest's
122 * "struct lguest_data" and see if there are any new ones marked "ready".
123 *
124 * We are careful to do these in order: obviously we respect the order the
125 * Guest put them in the ring, but we also promise the Guest that they will
126 * happen before any normal hypercall (which is why we check this before
127 * checking for a normal hcall). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700128static void do_async_hcalls(struct lguest *lg)
129{
130 unsigned int i;
131 u8 st[LHCALL_RING_SIZE];
132
Rusty Russellbff672e2007-07-26 10:41:04 -0700133 /* For simplicity, we copy the entire call status array in at once. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700134 if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
135 return;
136
Rusty Russellbff672e2007-07-26 10:41:04 -0700137
138 /* We process "struct lguest_data"s hcalls[] ring once. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700139 for (i = 0; i < ARRAY_SIZE(st); i++) {
140 struct lguest_regs regs;
Rusty Russellbff672e2007-07-26 10:41:04 -0700141 /* We remember where we were up to from last time. This makes
142 * sure that the hypercalls are done in the order the Guest
143 * places them in the ring. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700144 unsigned int n = lg->next_hcall;
145
Rusty Russellbff672e2007-07-26 10:41:04 -0700146 /* 0xFF means there's no call here (yet). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700147 if (st[n] == 0xFF)
148 break;
149
Rusty Russellbff672e2007-07-26 10:41:04 -0700150 /* OK, we have hypercall. Increment the "next_hcall" cursor,
151 * and wrap back to 0 if we reach the end. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700152 if (++lg->next_hcall == LHCALL_RING_SIZE)
153 lg->next_hcall = 0;
154
Rusty Russellbff672e2007-07-26 10:41:04 -0700155 /* We copy the hypercall arguments into a fake register
156 * structure. This makes life simple for do_hcall(). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700157 if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
158 || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
159 || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
160 || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
161 kill_guest(lg, "Fetching async hypercalls");
162 break;
163 }
164
Rusty Russellbff672e2007-07-26 10:41:04 -0700165 /* Do the hypercall, same as a normal one. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700166 do_hcall(lg, &regs);
Rusty Russellbff672e2007-07-26 10:41:04 -0700167
168 /* Mark the hypercall done. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700169 if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
170 kill_guest(lg, "Writing result for async hypercall");
171 break;
172 }
173
Rusty Russellbff672e2007-07-26 10:41:04 -0700174 /* Stop doing hypercalls if we've just done a DMA to the
175 * Launcher: it needs to service this first. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700176 if (lg->dma_is_pending)
177 break;
178 }
179}
180
Rusty Russellbff672e2007-07-26 10:41:04 -0700181/* Last of all, we look at what happens first of all. The very first time the
182 * Guest makes a hypercall, we end up here to set things up: */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700183static void initialize(struct lguest *lg)
184{
185 u32 tsc_speed;
186
Rusty Russellbff672e2007-07-26 10:41:04 -0700187 /* You can't do anything until you're initialized. The Guest knows the
188 * rules, so we're unforgiving here. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700189 if (lg->regs->eax != LHCALL_LGUEST_INIT) {
190 kill_guest(lg, "hypercall %li before LGUEST_INIT",
191 lg->regs->eax);
192 return;
193 }
194
Rusty Russellbff672e2007-07-26 10:41:04 -0700195 /* We insist that the Time Stamp Counter exist and doesn't change with
196 * cpu frequency. Some devious chip manufacturers decided that TSC
197 * changes could be handled in software. I decided that time going
198 * backwards might be good for benchmarks, but it's bad for users.
199 *
200 * We also insist that the TSC be stable: the kernel detects unreliable
201 * TSCs for its own purposes, and we use that here. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700202 if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
203 tsc_speed = tsc_khz;
204 else
205 tsc_speed = 0;
206
Rusty Russellbff672e2007-07-26 10:41:04 -0700207 /* The pointer to the Guest's "struct lguest_data" is the only
208 * argument. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700209 lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
Rusty Russellbff672e2007-07-26 10:41:04 -0700210 /* If we check the address they gave is OK now, we can simply
211 * copy_to_user/from_user from now on rather than using lgread/lgwrite.
212 * I put this in to show that I'm not immune to writing stupid
213 * optimizations. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700214 if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
215 kill_guest(lg, "bad guest page %p", lg->lguest_data);
216 return;
217 }
Rusty Russellbff672e2007-07-26 10:41:04 -0700218 /* The Guest tells us where we're not to deliver interrupts by putting
219 * the range of addresses into "struct lguest_data". */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700220 if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
221 || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
Rusty Russellbff672e2007-07-26 10:41:04 -0700222 /* We tell the Guest that it can't use the top 4MB of virtual
223 * addresses used by the Switcher. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700224 || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
225 || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
Rusty Russellbff672e2007-07-26 10:41:04 -0700226 /* We also give the Guest a unique id, as used in lguest_net.c. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700227 || put_user(lg->guestid, &lg->lguest_data->guestid))
228 kill_guest(lg, "bad guest page %p", lg->lguest_data);
229
Rusty Russell6c8dca52007-07-27 13:42:52 +1000230 /* We write the current time into the Guest's data page once now. */
231 write_timestamp(lg);
232
Rusty Russellbff672e2007-07-26 10:41:04 -0700233 /* This is the one case where the above accesses might have been the
234 * first write to a Guest page. This may have caused a copy-on-write
235 * fault, but the Guest might be referring to the old (read-only)
236 * page. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700237 guest_pagetable_clear_all(lg);
238}
Rusty Russellbff672e2007-07-26 10:41:04 -0700239/* Now we've examined the hypercall code; our Guest can make requests. There
240 * is one other way we can do things for the Guest, as we see in
241 * emulate_insn(). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700242
Rusty Russellbff672e2007-07-26 10:41:04 -0700243/*H:110 Tricky point: we mark the hypercall as "done" once we've done it.
244 * Normally we don't need to do this: the Guest will run again and update the
245 * trap number before we come back around the run_guest() loop to
246 * do_hypercalls().
247 *
248 * However, if we are signalled or the Guest sends DMA to the Launcher, that
249 * loop will exit without running the Guest. When it comes back it would try
250 * to re-run the hypercall. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700251static void clear_hcall(struct lguest *lg)
252{
253 lg->regs->trapnum = 255;
254}
255
Rusty Russellbff672e2007-07-26 10:41:04 -0700256/*H:100
257 * Hypercalls
258 *
259 * Remember from the Guest, hypercalls come in two flavors: normal and
260 * asynchronous. This file handles both of types.
261 */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700262void do_hypercalls(struct lguest *lg)
263{
Rusty Russellbff672e2007-07-26 10:41:04 -0700264 /* Not initialized yet? */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700265 if (unlikely(!lg->lguest_data)) {
Rusty Russellbff672e2007-07-26 10:41:04 -0700266 /* Did the Guest make a hypercall? We might have come back for
267 * some other reason (an interrupt, a different trap). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700268 if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
Rusty Russellbff672e2007-07-26 10:41:04 -0700269 /* Set up the "struct lguest_data" */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700270 initialize(lg);
Rusty Russellbff672e2007-07-26 10:41:04 -0700271 /* The hypercall is done. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700272 clear_hcall(lg);
273 }
274 return;
275 }
276
Rusty Russellbff672e2007-07-26 10:41:04 -0700277 /* The Guest has initialized.
278 *
279 * Look in the hypercall ring for the async hypercalls: */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700280 do_async_hcalls(lg);
Rusty Russellbff672e2007-07-26 10:41:04 -0700281
282 /* If we stopped reading the hypercall ring because the Guest did a
283 * SEND_DMA to the Launcher, we want to return now. Otherwise if the
284 * Guest asked us to do a hypercall, we do it. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700285 if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
286 do_hcall(lg, lg->regs);
Rusty Russellbff672e2007-07-26 10:41:04 -0700287 /* The hypercall is done. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700288 clear_hcall(lg);
289 }
290}
Rusty Russell6c8dca52007-07-27 13:42:52 +1000291
292/* This routine supplies the Guest with time: it's used for wallclock time at
293 * initial boot and as a rough time source if the TSC isn't available. */
294void write_timestamp(struct lguest *lg)
295{
296 struct timespec now;
297 ktime_get_real_ts(&now);
298 if (put_user(now, &lg->lguest_data->time))
299 kill_guest(lg, "Writing timestamp");
300}