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 lguest *lg, struct hcall_args *args)
35 case LHCALL_FLUSH_ASYNC:
36 /* This call does nothing, except by breaking out of the Guest
37 * it makes us process all the asynchronous hypercalls. */
39 case LHCALL_LGUEST_INIT:
40 /* You can't get here unless you're already initialized. Don't
42 kill_guest(lg, "already have lguest_data");
45 /* Crash is such a trivial hypercall that we do it in four
46 * lines right here. */
48 /* If the lgread fails, it will call kill_guest() itself; the
49 * kill_guest() with the message will be ignored. */
50 lgread(lg, msg, args->arg1, sizeof(msg));
51 msg[sizeof(msg)-1] = '\0';
52 kill_guest(lg, "CRASH: %s", msg);
55 case LHCALL_FLUSH_TLB:
56 /* FLUSH_TLB comes in two flavors, depending on the
59 guest_pagetable_clear_all(lg);
61 guest_pagetable_flush_user(lg);
64 /* 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. */
70 args->arg0 = bind_dma(lg, args->arg1, args->arg2,
71 args->arg3 >> 8, args->arg3 & 0xFF);
74 /* All these calls simply pass the arguments through to the right
77 send_dma(lg, args->arg1, args->arg2);
79 case LHCALL_NEW_PGTABLE:
80 guest_new_pagetable(lg, args->arg1);
82 case LHCALL_SET_STACK:
83 guest_set_stack(lg, args->arg1, args->arg2, args->arg3);
86 guest_set_pte(lg, args->arg1, args->arg2, mkgpte(args->arg3));
89 guest_set_pmd(lg, args->arg1, args->arg2);
91 case LHCALL_SET_CLOCKEVENT:
92 guest_set_clockevent(lg, args->arg1);
95 /* This sets the TS flag, as we saw used in run_guest(). */
99 /* Similarly, this sets the halted flag for run_guest(). */
103 if (lguest_arch_do_hcall(lg, args))
104 kill_guest(lg, "Bad hypercall %li\n", args->arg0);
109 /*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".
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). */
116 static void do_async_hcalls(struct lguest *lg)
119 u8 st[LHCALL_RING_SIZE];
121 /* For simplicity, we copy the entire call status array in at once. */
122 if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
125 /* We process "struct lguest_data"s hcalls[] ring once. */
126 for (i = 0; i < ARRAY_SIZE(st); i++) {
127 struct hcall_args args;
128 /* 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. */
131 unsigned int n = lg->next_hcall;
133 /* 0xFF means there's no call here (yet). */
137 /* OK, we have hypercall. Increment the "next_hcall" cursor,
138 * and wrap back to 0 if we reach the end. */
139 if (++lg->next_hcall == LHCALL_RING_SIZE)
142 /* 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))) {
146 kill_guest(lg, "Fetching async hypercalls");
150 /* Do the hypercall, same as a normal one. */
153 /* Mark the hypercall done. */
154 if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
155 kill_guest(lg, "Writing result for async hypercall");
159 /* Stop doing hypercalls if we've just done a DMA to the
160 * Launcher: it needs to service this first. */
161 if (lg->dma_is_pending)
166 /* 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: */
168 static void initialize(struct lguest *lg)
171 /* You can't do anything until you're initialized. The Guest knows the
172 * rules, so we're unforgiving here. */
173 if (lg->hcall->arg0 != LHCALL_LGUEST_INIT) {
174 kill_guest(lg, "hypercall %li before INIT", lg->hcall->arg0);
178 if (lguest_arch_init_hypercalls(lg))
179 kill_guest(lg, "bad guest page %p", lg->lguest_data);
181 /* The Guest tells us where we're not to deliver interrupts by putting
182 * the range of addresses into "struct lguest_data". */
183 if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
184 || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
185 /* We tell the Guest that it can't use the top 4MB of virtual
186 * addresses used by the Switcher. */
187 || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem))
188 kill_guest(lg, "bad guest page %p", lg->lguest_data);
190 /* We write the current time into the Guest's data page once now. */
193 /* 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)
197 guest_pagetable_clear_all(lg);
203 * Remember from the Guest, hypercalls come in two flavors: normal and
204 * asynchronous. This file handles both of types.
206 void do_hypercalls(struct lguest *lg)
208 /* Not initialized yet? This hypercall must do it. */
209 if (unlikely(!lg->lguest_data)) {
210 /* Set up the "struct lguest_data" */
217 /* The Guest has initialized.
219 * Look in the hypercall ring for the async hypercalls: */
222 /* If we stopped reading the hypercall ring because the Guest did a
223 * SEND_DMA to the Launcher, we want to return now. Otherwise we do
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.
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
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. */
243 void write_timestamp(struct lguest *lg)
246 ktime_get_real_ts(&now);
247 if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec)))
248 kill_guest(lg, "Writing timestamp");