1 /*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. :*/
7 /* Copyright (C) 2006 Rusty Russell IBM Corporation
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.
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.
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
23 #include <linux/uaccess.h>
24 #include <linux/syscalls.h>
27 #include <asm/pgtable.h>
30 /*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. */
32 static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
34 struct lguest *lg = cpu->lg;
37 case LHCALL_FLUSH_ASYNC:
38 /* This call does nothing, except by breaking out of the Guest
39 * it makes us process all the asynchronous hypercalls. */
41 case LHCALL_LGUEST_INIT:
42 /* You can't get here unless you're already initialized. Don't
44 kill_guest(lg, "already have lguest_data");
46 case LHCALL_SHUTDOWN: {
47 /* Shutdown is such a trivial hypercall that we do it in four
48 * lines right here. */
50 /* If the lgread fails, it will call kill_guest() itself; the
51 * kill_guest() with the message will be ignored. */
52 __lgread(lg, msg, args->arg1, sizeof(msg));
53 msg[sizeof(msg)-1] = '\0';
54 kill_guest(lg, "CRASH: %s", msg);
55 if (args->arg2 == LGUEST_SHUTDOWN_RESTART)
56 lg->dead = ERR_PTR(-ERESTART);
59 case LHCALL_FLUSH_TLB:
60 /* FLUSH_TLB comes in two flavors, depending on the
63 guest_pagetable_clear_all(cpu);
65 guest_pagetable_flush_user(cpu);
68 /* All these calls simply pass the arguments through to the right
70 case LHCALL_NEW_PGTABLE:
71 guest_new_pagetable(cpu, args->arg1);
73 case LHCALL_SET_STACK:
74 guest_set_stack(cpu, args->arg1, args->arg2, args->arg3);
77 guest_set_pte(lg, args->arg1, args->arg2, __pte(args->arg3));
80 guest_set_pmd(lg, args->arg1, args->arg2);
82 case LHCALL_SET_CLOCKEVENT:
83 guest_set_clockevent(cpu, args->arg1);
86 /* This sets the TS flag, as we saw used in run_guest(). */
90 /* Similarly, this sets the halted flag for run_guest(). */
94 cpu->pending_notify = args->arg1;
97 /* It should be an architecture-specific hypercall. */
98 if (lguest_arch_do_hcall(cpu, args))
99 kill_guest(lg, "Bad hypercall %li\n", args->arg0);
104 /*H:124 Asynchronous hypercalls are easy: we just look in the array in the
105 * Guest's "struct lguest_data" to see if any new ones are marked "ready".
107 * We are careful to do these in order: obviously we respect the order the
108 * Guest put them in the ring, but we also promise the Guest that they will
109 * happen before any normal hypercall (which is why we check this before
110 * checking for a normal hcall). */
111 static void do_async_hcalls(struct lg_cpu *cpu)
114 u8 st[LHCALL_RING_SIZE];
115 struct lguest *lg = cpu->lg;
117 /* For simplicity, we copy the entire call status array in at once. */
118 if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
121 /* We process "struct lguest_data"s hcalls[] ring once. */
122 for (i = 0; i < ARRAY_SIZE(st); i++) {
123 struct hcall_args args;
124 /* We remember where we were up to from last time. This makes
125 * sure that the hypercalls are done in the order the Guest
126 * places them in the ring. */
127 unsigned int n = cpu->next_hcall;
129 /* 0xFF means there's no call here (yet). */
133 /* OK, we have hypercall. Increment the "next_hcall" cursor,
134 * and wrap back to 0 if we reach the end. */
135 if (++cpu->next_hcall == LHCALL_RING_SIZE)
138 /* Copy the hypercall arguments into a local copy of
139 * the hcall_args struct. */
140 if (copy_from_user(&args, &lg->lguest_data->hcalls[n],
141 sizeof(struct hcall_args))) {
142 kill_guest(lg, "Fetching async hypercalls");
146 /* Do the hypercall, same as a normal one. */
147 do_hcall(cpu, &args);
149 /* Mark the hypercall done. */
150 if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
151 kill_guest(lg, "Writing result for async hypercall");
155 /* Stop doing hypercalls if they want to notify the Launcher:
156 * it needs to service this first. */
157 if (cpu->pending_notify)
162 /* Last of all, we look at what happens first of all. The very first time the
163 * Guest makes a hypercall, we end up here to set things up: */
164 static void initialize(struct lg_cpu *cpu)
166 struct lguest *lg = cpu->lg;
167 /* You can't do anything until you're initialized. The Guest knows the
168 * rules, so we're unforgiving here. */
169 if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) {
170 kill_guest(lg, "hypercall %li before INIT", cpu->hcall->arg0);
174 if (lguest_arch_init_hypercalls(cpu))
175 kill_guest(lg, "bad guest page %p", lg->lguest_data);
177 /* The Guest tells us where we're not to deliver interrupts by putting
178 * the range of addresses into "struct lguest_data". */
179 if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
180 || get_user(lg->noirq_end, &lg->lguest_data->noirq_end))
181 kill_guest(lg, "bad guest page %p", lg->lguest_data);
183 /* We write the current time into the Guest's data page once so it can
187 /* page_tables.c will also do some setup. */
188 page_table_guest_data_init(lg);
190 /* This is the one case where the above accesses might have been the
191 * first write to a Guest page. This may have caused a copy-on-write
192 * fault, but the old page might be (read-only) in the Guest
194 guest_pagetable_clear_all(cpu);
200 * Remember from the Guest, hypercalls come in two flavors: normal and
201 * asynchronous. This file handles both of types.
203 void do_hypercalls(struct lg_cpu *cpu)
205 /* Not initialized yet? This hypercall must do it. */
206 if (unlikely(!cpu->lg->lguest_data)) {
207 /* Set up the "struct lguest_data" */
214 /* The Guest has initialized.
216 * Look in the hypercall ring for the async hypercalls: */
217 do_async_hcalls(cpu);
219 /* If we stopped reading the hypercall ring because the Guest did a
220 * NOTIFY to the Launcher, we want to return now. Otherwise we do
222 if (!cpu->pending_notify) {
223 do_hcall(cpu, cpu->hcall);
224 /* Tricky point: we reset the hcall pointer to mark the
225 * hypercall as "done". We use the hcall pointer rather than
226 * the trap number to indicate a hypercall is pending.
227 * Normally it doesn't matter: the Guest will run again and
228 * update the trap number before we come back here.
230 * However, if we are signalled or the Guest sends I/O to the
231 * Launcher, the run_guest() loop will exit without running the
232 * Guest. When it comes back it would try to re-run the
238 /* This routine supplies the Guest with time: it's used for wallclock time at
239 * initial boot and as a rough time source if the TSC isn't available. */
240 void write_timestamp(struct lguest *lg)
243 ktime_get_real_ts(&now);
244 if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec)))
245 kill_guest(lg, "Writing timestamp");