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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>
Rusty Russelld7e28ff2007-07-19 01:49:23 -070028#include "lg.h"
29
Jes Sorensenb410e7b2007-10-22 11:03:31 +100030/*H:120 This is the core hypercall routine: where the Guest gets what it wants.
31 * Or gets killed. Or, in the case of LHCALL_CRASH, both. */
32static void do_hcall(struct lguest *lg, struct hcall_args *args)
Rusty Russelld7e28ff2007-07-19 01:49:23 -070033{
Jes Sorensenb410e7b2007-10-22 11:03:31 +100034 switch (args->arg0) {
Rusty Russelld7e28ff2007-07-19 01:49:23 -070035 case LHCALL_FLUSH_ASYNC:
Rusty Russellbff672e2007-07-26 10:41:04 -070036 /* This call does nothing, except by breaking out of the Guest
37 * it makes us process all the asynchronous hypercalls. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070038 break;
39 case LHCALL_LGUEST_INIT:
Rusty Russellbff672e2007-07-26 10:41:04 -070040 /* You can't get here unless you're already initialized. Don't
41 * do that. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070042 kill_guest(lg, "already have lguest_data");
43 break;
44 case LHCALL_CRASH: {
Rusty Russellbff672e2007-07-26 10:41:04 -070045 /* Crash is such a trivial hypercall that we do it in four
46 * lines right here. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070047 char msg[128];
Rusty Russellbff672e2007-07-26 10:41:04 -070048 /* If the lgread fails, it will call kill_guest() itself; the
49 * kill_guest() with the message will be ignored. */
Jes Sorensenb410e7b2007-10-22 11:03:31 +100050 lgread(lg, msg, args->arg1, sizeof(msg));
Rusty Russelld7e28ff2007-07-19 01:49:23 -070051 msg[sizeof(msg)-1] = '\0';
52 kill_guest(lg, "CRASH: %s", msg);
53 break;
54 }
55 case LHCALL_FLUSH_TLB:
Rusty Russellbff672e2007-07-26 10:41:04 -070056 /* FLUSH_TLB comes in two flavors, depending on the
57 * argument: */
Jes Sorensenb410e7b2007-10-22 11:03:31 +100058 if (args->arg1)
Rusty Russelld7e28ff2007-07-19 01:49:23 -070059 guest_pagetable_clear_all(lg);
60 else
61 guest_pagetable_flush_user(lg);
62 break;
Rusty Russelld7e28ff2007-07-19 01:49:23 -070063 case LHCALL_BIND_DMA:
Rusty Russellbff672e2007-07-26 10:41:04 -070064 /* BIND_DMA really wants four arguments, but it's the only call
65 * which does. So the Guest packs the number of buffers and
66 * the interrupt number into the final argument, and we decode
67 * it here. This can legitimately fail, since we currently
68 * place a limit on the number of DMA pools a Guest can have.
69 * So we return true or false from this call. */
Jes Sorensenb410e7b2007-10-22 11:03:31 +100070 args->arg0 = bind_dma(lg, args->arg1, args->arg2,
71 args->arg3 >> 8, args->arg3 & 0xFF);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070072 break;
Rusty Russellbff672e2007-07-26 10:41:04 -070073
74 /* All these calls simply pass the arguments through to the right
75 * routines. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -070076 case LHCALL_SEND_DMA:
Jes Sorensenb410e7b2007-10-22 11:03:31 +100077 send_dma(lg, args->arg1, args->arg2);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070078 break;
79 case LHCALL_NEW_PGTABLE:
Jes Sorensenb410e7b2007-10-22 11:03:31 +100080 guest_new_pagetable(lg, args->arg1);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070081 break;
82 case LHCALL_SET_STACK:
Jes Sorensenb410e7b2007-10-22 11:03:31 +100083 guest_set_stack(lg, args->arg1, args->arg2, args->arg3);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070084 break;
85 case LHCALL_SET_PTE:
Matias Zabaljaureguidf29f432007-10-22 11:03:33 +100086 guest_set_pte(lg, args->arg1, args->arg2, __pte(args->arg3));
Rusty Russelld7e28ff2007-07-19 01:49:23 -070087 break;
88 case LHCALL_SET_PMD:
Jes Sorensenb410e7b2007-10-22 11:03:31 +100089 guest_set_pmd(lg, args->arg1, args->arg2);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070090 break;
91 case LHCALL_SET_CLOCKEVENT:
Jes Sorensenb410e7b2007-10-22 11:03:31 +100092 guest_set_clockevent(lg, args->arg1);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070093 break;
94 case LHCALL_TS:
Rusty Russellbff672e2007-07-26 10:41:04 -070095 /* This sets the TS flag, as we saw used in run_guest(). */
Jes Sorensenb410e7b2007-10-22 11:03:31 +100096 lg->ts = args->arg1;
Rusty Russelld7e28ff2007-07-19 01:49:23 -070097 break;
98 case LHCALL_HALT:
Rusty Russellbff672e2007-07-26 10:41:04 -070099 /* Similarly, this sets the halted flag for run_guest(). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700100 lg->halted = 1;
101 break;
102 default:
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000103 if (lguest_arch_do_hcall(lg, args))
104 kill_guest(lg, "Bad hypercall %li\n", args->arg0);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700105 }
106}
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000107/*:*/
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700108
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000109/*H:124 Asynchronous hypercalls are easy: we just look in the array in the
110 * Guest's "struct lguest_data" to see if any new ones are marked "ready".
Rusty Russellbff672e2007-07-26 10:41:04 -0700111 *
112 * We are careful to do these in order: obviously we respect the order the
113 * Guest put them in the ring, but we also promise the Guest that they will
114 * happen before any normal hypercall (which is why we check this before
115 * checking for a normal hcall). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700116static void do_async_hcalls(struct lguest *lg)
117{
118 unsigned int i;
119 u8 st[LHCALL_RING_SIZE];
120
Rusty Russellbff672e2007-07-26 10:41:04 -0700121 /* For simplicity, we copy the entire call status array in at once. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700122 if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
123 return;
124
Rusty Russellbff672e2007-07-26 10:41:04 -0700125 /* We process "struct lguest_data"s hcalls[] ring once. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700126 for (i = 0; i < ARRAY_SIZE(st); i++) {
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000127 struct hcall_args args;
Rusty Russellbff672e2007-07-26 10:41:04 -0700128 /* We remember where we were up to from last time. This makes
129 * sure that the hypercalls are done in the order the Guest
130 * places them in the ring. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700131 unsigned int n = lg->next_hcall;
132
Rusty Russellbff672e2007-07-26 10:41:04 -0700133 /* 0xFF means there's no call here (yet). */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700134 if (st[n] == 0xFF)
135 break;
136
Rusty Russellbff672e2007-07-26 10:41:04 -0700137 /* OK, we have hypercall. Increment the "next_hcall" cursor,
138 * and wrap back to 0 if we reach the end. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700139 if (++lg->next_hcall == LHCALL_RING_SIZE)
140 lg->next_hcall = 0;
141
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000142 /* Copy the hypercall arguments into a local copy of
143 * the hcall_args struct. */
144 if (copy_from_user(&args, &lg->lguest_data->hcalls[n],
145 sizeof(struct hcall_args))) {
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700146 kill_guest(lg, "Fetching async hypercalls");
147 break;
148 }
149
Rusty Russellbff672e2007-07-26 10:41:04 -0700150 /* Do the hypercall, same as a normal one. */
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000151 do_hcall(lg, &args);
Rusty Russellbff672e2007-07-26 10:41:04 -0700152
153 /* Mark the hypercall done. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700154 if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
155 kill_guest(lg, "Writing result for async hypercall");
156 break;
157 }
158
Rusty Russellbff672e2007-07-26 10:41:04 -0700159 /* Stop doing hypercalls if we've just done a DMA to the
160 * Launcher: it needs to service this first. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700161 if (lg->dma_is_pending)
162 break;
163 }
164}
165
Rusty Russellbff672e2007-07-26 10:41:04 -0700166/* Last of all, we look at what happens first of all. The very first time the
167 * Guest makes a hypercall, we end up here to set things up: */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700168static void initialize(struct lguest *lg)
169{
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700170
Rusty Russellbff672e2007-07-26 10:41:04 -0700171 /* You can't do anything until you're initialized. The Guest knows the
172 * rules, so we're unforgiving here. */
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000173 if (lg->hcall->arg0 != LHCALL_LGUEST_INIT) {
174 kill_guest(lg, "hypercall %li before INIT", lg->hcall->arg0);
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700175 return;
176 }
177
Jes Sorensenb410e7b2007-10-22 11:03:31 +1000178 if (lguest_arch_init_hypercalls(lg))
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700179 kill_guest(lg, "bad guest page %p", lg->lguest_data);
Rusty Russell3c6b5bf2007-10-22 11:03:26 +1000180
Rusty Russellbff672e2007-07-26 10:41:04 -0700181 /* The Guest tells us where we're not to deliver interrupts by putting
182 * the range of addresses into "struct lguest_data". */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700183 if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
Rusty Russell47436aa2007-10-22 11:03:36 +1000184 || get_user(lg->noirq_end, &lg->lguest_data->noirq_end))
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700185 kill_guest(lg, "bad guest page %p", lg->lguest_data);
186
Rusty Russell6c8dca52007-07-27 13:42:52 +1000187 /* We write the current time into the Guest's data page once now. */
188 write_timestamp(lg);
189
Rusty Russell47436aa2007-10-22 11:03:36 +1000190 /* page_tables.c will also do some setup. */
191 page_table_guest_data_init(lg);
192
Rusty Russellbff672e2007-07-26 10:41:04 -0700193 /* This is the one case where the above accesses might have been the
194 * first write to a Guest page. This may have caused a copy-on-write
195 * fault, but the Guest might be referring to the old (read-only)
196 * page. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700197 guest_pagetable_clear_all(lg);
198}
199
Rusty Russellbff672e2007-07-26 10:41:04 -0700200/*H:100
201 * Hypercalls
202 *
203 * Remember from the Guest, hypercalls come in two flavors: normal and
204 * asynchronous. This file handles both of types.
205 */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700206void do_hypercalls(struct lguest *lg)
207{
Rusty Russellcc6d4fb2007-10-22 11:03:30 +1000208 /* Not initialized yet? This hypercall must do it. */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700209 if (unlikely(!lg->lguest_data)) {
Rusty Russellcc6d4fb2007-10-22 11:03:30 +1000210 /* Set up the "struct lguest_data" */
211 initialize(lg);
212 /* Hcall is done. */
213 lg->hcall = NULL;
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700214 return;
215 }
216
Rusty Russellbff672e2007-07-26 10:41:04 -0700217 /* The Guest has initialized.
218 *
219 * Look in the hypercall ring for the async hypercalls: */
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700220 do_async_hcalls(lg);
Rusty Russellbff672e2007-07-26 10:41:04 -0700221
222 /* If we stopped reading the hypercall ring because the Guest did a
Rusty Russellcc6d4fb2007-10-22 11:03:30 +1000223 * SEND_DMA to the Launcher, we want to return now. Otherwise we do
224 * the hypercall. */
225 if (!lg->dma_is_pending) {
226 do_hcall(lg, lg->hcall);
227 /* Tricky point: we reset the hcall pointer to mark the
228 * hypercall as "done". We use the hcall pointer rather than
229 * the trap number to indicate a hypercall is pending.
230 * Normally it doesn't matter: the Guest will run again and
231 * update the trap number before we come back here.
232 *
233 * However, if we are signalled or the Guest sends DMA to the
234 * Launcher, the run_guest() loop will exit without running the
235 * Guest. When it comes back it would try to re-run the
236 * hypercall. */
237 lg->hcall = NULL;
Rusty Russelld7e28ff2007-07-19 01:49:23 -0700238 }
239}
Rusty Russell6c8dca52007-07-27 13:42:52 +1000240
241/* This routine supplies the Guest with time: it's used for wallclock time at
242 * initial boot and as a rough time source if the TSC isn't available. */
243void write_timestamp(struct lguest *lg)
244{
245 struct timespec now;
246 ktime_get_real_ts(&now);
Jes Sorensen891ff652007-10-22 10:56:22 +1000247 if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec)))
Rusty Russell6c8dca52007-07-27 13:42:52 +1000248 kill_guest(lg, "Writing timestamp");
249}