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>
26 #include <linux/ktime.h>
28 #include <asm/pgtable.h>
31 /*H:120 This is the core hypercall routine: where the Guest gets what it wants.
32 * Or gets killed. Or, in the case of LHCALL_SHUTDOWN, both. */
33 static void do_hcall(struct lg_cpu
*cpu
, struct hcall_args
*args
)
36 case LHCALL_FLUSH_ASYNC
:
37 /* This call does nothing, except by breaking out of the Guest
38 * it makes us process all the asynchronous hypercalls. */
40 case LHCALL_LGUEST_INIT
:
41 /* You can't get here unless you're already initialized. Don't
43 kill_guest(cpu
, "already have lguest_data");
45 case LHCALL_SHUTDOWN
: {
46 /* Shutdown is such a trivial hypercall that we do it in four
47 * lines right here. */
49 /* If the lgread fails, it will call kill_guest() itself; the
50 * kill_guest() with the message will be ignored. */
51 __lgread(cpu
, msg
, args
->arg1
, sizeof(msg
));
52 msg
[sizeof(msg
)-1] = '\0';
53 kill_guest(cpu
, "CRASH: %s", msg
);
54 if (args
->arg2
== LGUEST_SHUTDOWN_RESTART
)
55 cpu
->lg
->dead
= ERR_PTR(-ERESTART
);
58 case LHCALL_FLUSH_TLB
:
59 /* FLUSH_TLB comes in two flavors, depending on the
62 guest_pagetable_clear_all(cpu
);
64 guest_pagetable_flush_user(cpu
);
67 /* All these calls simply pass the arguments through to the right
69 case LHCALL_NEW_PGTABLE
:
70 guest_new_pagetable(cpu
, args
->arg1
);
72 case LHCALL_SET_STACK
:
73 guest_set_stack(cpu
, args
->arg1
, args
->arg2
, args
->arg3
);
76 guest_set_pte(cpu
, args
->arg1
, args
->arg2
, __pte(args
->arg3
));
79 guest_set_pmd(cpu
->lg
, args
->arg1
, args
->arg2
);
81 case LHCALL_SET_CLOCKEVENT
:
82 guest_set_clockevent(cpu
, args
->arg1
);
85 /* This sets the TS flag, as we saw used in run_guest(). */
89 /* Similarly, this sets the halted flag for run_guest(). */
93 cpu
->pending_notify
= args
->arg1
;
96 /* It should be an architecture-specific hypercall. */
97 if (lguest_arch_do_hcall(cpu
, args
))
98 kill_guest(cpu
, "Bad hypercall %li\n", args
->arg0
);
103 /*H:124 Asynchronous hypercalls are easy: we just look in the array in the
104 * Guest's "struct lguest_data" to see if any new ones are marked "ready".
106 * We are careful to do these in order: obviously we respect the order the
107 * Guest put them in the ring, but we also promise the Guest that they will
108 * happen before any normal hypercall (which is why we check this before
109 * checking for a normal hcall). */
110 static void do_async_hcalls(struct lg_cpu
*cpu
)
113 u8 st
[LHCALL_RING_SIZE
];
115 /* For simplicity, we copy the entire call status array in at once. */
116 if (copy_from_user(&st
, &cpu
->lg
->lguest_data
->hcall_status
, sizeof(st
)))
119 /* We process "struct lguest_data"s hcalls[] ring once. */
120 for (i
= 0; i
< ARRAY_SIZE(st
); i
++) {
121 struct hcall_args args
;
122 /* We remember where we were up to from last time. This makes
123 * sure that the hypercalls are done in the order the Guest
124 * places them in the ring. */
125 unsigned int n
= cpu
->next_hcall
;
127 /* 0xFF means there's no call here (yet). */
131 /* OK, we have hypercall. Increment the "next_hcall" cursor,
132 * and wrap back to 0 if we reach the end. */
133 if (++cpu
->next_hcall
== LHCALL_RING_SIZE
)
136 /* Copy the hypercall arguments into a local copy of
137 * the hcall_args struct. */
138 if (copy_from_user(&args
, &cpu
->lg
->lguest_data
->hcalls
[n
],
139 sizeof(struct hcall_args
))) {
140 kill_guest(cpu
, "Fetching async hypercalls");
144 /* Do the hypercall, same as a normal one. */
145 do_hcall(cpu
, &args
);
147 /* Mark the hypercall done. */
148 if (put_user(0xFF, &cpu
->lg
->lguest_data
->hcall_status
[n
])) {
149 kill_guest(cpu
, "Writing result for async hypercall");
153 /* Stop doing hypercalls if they want to notify the Launcher:
154 * it needs to service this first. */
155 if (cpu
->pending_notify
)
160 /* Last of all, we look at what happens first of all. The very first time the
161 * Guest makes a hypercall, we end up here to set things up: */
162 static void initialize(struct lg_cpu
*cpu
)
164 /* You can't do anything until you're initialized. The Guest knows the
165 * rules, so we're unforgiving here. */
166 if (cpu
->hcall
->arg0
!= LHCALL_LGUEST_INIT
) {
167 kill_guest(cpu
, "hypercall %li before INIT", cpu
->hcall
->arg0
);
171 if (lguest_arch_init_hypercalls(cpu
))
172 kill_guest(cpu
, "bad guest page %p", cpu
->lg
->lguest_data
);
174 /* The Guest tells us where we're not to deliver interrupts by putting
175 * the range of addresses into "struct lguest_data". */
176 if (get_user(cpu
->lg
->noirq_start
, &cpu
->lg
->lguest_data
->noirq_start
)
177 || get_user(cpu
->lg
->noirq_end
, &cpu
->lg
->lguest_data
->noirq_end
))
178 kill_guest(cpu
, "bad guest page %p", cpu
->lg
->lguest_data
);
180 /* We write the current time into the Guest's data page once so it can
182 write_timestamp(cpu
);
184 /* page_tables.c will also do some setup. */
185 page_table_guest_data_init(cpu
);
187 /* This is the one case where the above accesses might have been the
188 * first write to a Guest page. This may have caused a copy-on-write
189 * fault, but the old page might be (read-only) in the Guest
191 guest_pagetable_clear_all(cpu
);
195 /*M:013 If a Guest reads from a page (so creates a mapping) that it has never
196 * written to, and then the Launcher writes to it (ie. the output of a virtual
197 * device), the Guest will still see the old page. In practice, this never
198 * happens: why would the Guest read a page which it has never written to? But
199 * a similar scenario might one day bite us, so it's worth mentioning. :*/
204 * Remember from the Guest, hypercalls come in two flavors: normal and
205 * asynchronous. This file handles both of types.
207 void do_hypercalls(struct lg_cpu
*cpu
)
209 /* Not initialized yet? This hypercall must do it. */
210 if (unlikely(!cpu
->lg
->lguest_data
)) {
211 /* Set up the "struct lguest_data" */
218 /* The Guest has initialized.
220 * Look in the hypercall ring for the async hypercalls: */
221 do_async_hcalls(cpu
);
223 /* If we stopped reading the hypercall ring because the Guest did a
224 * NOTIFY to the Launcher, we want to return now. Otherwise we do
226 if (!cpu
->pending_notify
) {
227 do_hcall(cpu
, cpu
->hcall
);
228 /* Tricky point: we reset the hcall pointer to mark the
229 * hypercall as "done". We use the hcall pointer rather than
230 * the trap number to indicate a hypercall is pending.
231 * Normally it doesn't matter: the Guest will run again and
232 * update the trap number before we come back here.
234 * However, if we are signalled or the Guest sends I/O to the
235 * Launcher, the run_guest() loop will exit without running the
236 * Guest. When it comes back it would try to re-run the
237 * hypercall. Finding that bug sucked. */
242 /* This routine supplies the Guest with time: it's used for wallclock time at
243 * initial boot and as a rough time source if the TSC isn't available. */
244 void write_timestamp(struct lg_cpu
*cpu
)
247 ktime_get_real_ts(&now
);
248 if (copy_to_user(&cpu
->lg
->lguest_data
->time
,
249 &now
, sizeof(struct timespec
)))
250 kill_guest(cpu
, "Writing timestamp");