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f938d2c8 RR |
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. :*/ | |
6 | ||
7 | /* Copyright (C) 2006 Rusty Russell IBM Corporation | |
d7e28ffe RR |
8 | |
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> | |
d7e28ffe RR |
28 | #include "lg.h" |
29 | ||
b410e7b1 JS |
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) | |
d7e28ffe | 33 | { |
b410e7b1 | 34 | switch (args->arg0) { |
d7e28ffe | 35 | case LHCALL_FLUSH_ASYNC: |
bff672e6 RR |
36 | /* This call does nothing, except by breaking out of the Guest |
37 | * it makes us process all the asynchronous hypercalls. */ | |
d7e28ffe RR |
38 | break; |
39 | case LHCALL_LGUEST_INIT: | |
bff672e6 RR |
40 | /* You can't get here unless you're already initialized. Don't |
41 | * do that. */ | |
d7e28ffe RR |
42 | kill_guest(lg, "already have lguest_data"); |
43 | break; | |
44 | case LHCALL_CRASH: { | |
bff672e6 RR |
45 | /* Crash is such a trivial hypercall that we do it in four |
46 | * lines right here. */ | |
d7e28ffe | 47 | char msg[128]; |
bff672e6 RR |
48 | /* If the lgread fails, it will call kill_guest() itself; the |
49 | * kill_guest() with the message will be ignored. */ | |
2d37f94a | 50 | __lgread(lg, msg, args->arg1, sizeof(msg)); |
d7e28ffe RR |
51 | msg[sizeof(msg)-1] = '\0'; |
52 | kill_guest(lg, "CRASH: %s", msg); | |
53 | break; | |
54 | } | |
55 | case LHCALL_FLUSH_TLB: | |
bff672e6 RR |
56 | /* FLUSH_TLB comes in two flavors, depending on the |
57 | * argument: */ | |
b410e7b1 | 58 | if (args->arg1) |
d7e28ffe RR |
59 | guest_pagetable_clear_all(lg); |
60 | else | |
61 | guest_pagetable_flush_user(lg); | |
62 | break; | |
bff672e6 RR |
63 | |
64 | /* All these calls simply pass the arguments through to the right | |
65 | * routines. */ | |
d7e28ffe | 66 | case LHCALL_NEW_PGTABLE: |
b410e7b1 | 67 | guest_new_pagetable(lg, args->arg1); |
d7e28ffe RR |
68 | break; |
69 | case LHCALL_SET_STACK: | |
b410e7b1 | 70 | guest_set_stack(lg, args->arg1, args->arg2, args->arg3); |
d7e28ffe RR |
71 | break; |
72 | case LHCALL_SET_PTE: | |
df29f43e | 73 | guest_set_pte(lg, args->arg1, args->arg2, __pte(args->arg3)); |
d7e28ffe RR |
74 | break; |
75 | case LHCALL_SET_PMD: | |
b410e7b1 | 76 | guest_set_pmd(lg, args->arg1, args->arg2); |
d7e28ffe RR |
77 | break; |
78 | case LHCALL_SET_CLOCKEVENT: | |
b410e7b1 | 79 | guest_set_clockevent(lg, args->arg1); |
d7e28ffe RR |
80 | break; |
81 | case LHCALL_TS: | |
bff672e6 | 82 | /* This sets the TS flag, as we saw used in run_guest(). */ |
b410e7b1 | 83 | lg->ts = args->arg1; |
d7e28ffe RR |
84 | break; |
85 | case LHCALL_HALT: | |
bff672e6 | 86 | /* Similarly, this sets the halted flag for run_guest(). */ |
d7e28ffe RR |
87 | lg->halted = 1; |
88 | break; | |
15045275 RR |
89 | case LHCALL_NOTIFY: |
90 | lg->pending_notify = args->arg1; | |
91 | break; | |
d7e28ffe | 92 | default: |
e1e72965 | 93 | /* It should be an architecture-specific hypercall. */ |
b410e7b1 JS |
94 | if (lguest_arch_do_hcall(lg, args)) |
95 | kill_guest(lg, "Bad hypercall %li\n", args->arg0); | |
d7e28ffe RR |
96 | } |
97 | } | |
b410e7b1 | 98 | /*:*/ |
d7e28ffe | 99 | |
b410e7b1 JS |
100 | /*H:124 Asynchronous hypercalls are easy: we just look in the array in the |
101 | * Guest's "struct lguest_data" to see if any new ones are marked "ready". | |
bff672e6 RR |
102 | * |
103 | * We are careful to do these in order: obviously we respect the order the | |
104 | * Guest put them in the ring, but we also promise the Guest that they will | |
105 | * happen before any normal hypercall (which is why we check this before | |
106 | * checking for a normal hcall). */ | |
d7e28ffe RR |
107 | static void do_async_hcalls(struct lguest *lg) |
108 | { | |
109 | unsigned int i; | |
110 | u8 st[LHCALL_RING_SIZE]; | |
111 | ||
bff672e6 | 112 | /* For simplicity, we copy the entire call status array in at once. */ |
d7e28ffe RR |
113 | if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st))) |
114 | return; | |
115 | ||
bff672e6 | 116 | /* We process "struct lguest_data"s hcalls[] ring once. */ |
d7e28ffe | 117 | for (i = 0; i < ARRAY_SIZE(st); i++) { |
b410e7b1 | 118 | struct hcall_args args; |
bff672e6 RR |
119 | /* We remember where we were up to from last time. This makes |
120 | * sure that the hypercalls are done in the order the Guest | |
121 | * places them in the ring. */ | |
d7e28ffe RR |
122 | unsigned int n = lg->next_hcall; |
123 | ||
bff672e6 | 124 | /* 0xFF means there's no call here (yet). */ |
d7e28ffe RR |
125 | if (st[n] == 0xFF) |
126 | break; | |
127 | ||
bff672e6 RR |
128 | /* OK, we have hypercall. Increment the "next_hcall" cursor, |
129 | * and wrap back to 0 if we reach the end. */ | |
d7e28ffe RR |
130 | if (++lg->next_hcall == LHCALL_RING_SIZE) |
131 | lg->next_hcall = 0; | |
132 | ||
b410e7b1 JS |
133 | /* Copy the hypercall arguments into a local copy of |
134 | * the hcall_args struct. */ | |
135 | if (copy_from_user(&args, &lg->lguest_data->hcalls[n], | |
136 | sizeof(struct hcall_args))) { | |
d7e28ffe RR |
137 | kill_guest(lg, "Fetching async hypercalls"); |
138 | break; | |
139 | } | |
140 | ||
bff672e6 | 141 | /* Do the hypercall, same as a normal one. */ |
b410e7b1 | 142 | do_hcall(lg, &args); |
bff672e6 RR |
143 | |
144 | /* Mark the hypercall done. */ | |
d7e28ffe RR |
145 | if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) { |
146 | kill_guest(lg, "Writing result for async hypercall"); | |
147 | break; | |
148 | } | |
149 | ||
15045275 RR |
150 | /* Stop doing hypercalls if they want to notify the Launcher: |
151 | * it needs to service this first. */ | |
152 | if (lg->pending_notify) | |
d7e28ffe RR |
153 | break; |
154 | } | |
155 | } | |
156 | ||
bff672e6 RR |
157 | /* Last of all, we look at what happens first of all. The very first time the |
158 | * Guest makes a hypercall, we end up here to set things up: */ | |
d7e28ffe RR |
159 | static void initialize(struct lguest *lg) |
160 | { | |
bff672e6 RR |
161 | /* You can't do anything until you're initialized. The Guest knows the |
162 | * rules, so we're unforgiving here. */ | |
b410e7b1 JS |
163 | if (lg->hcall->arg0 != LHCALL_LGUEST_INIT) { |
164 | kill_guest(lg, "hypercall %li before INIT", lg->hcall->arg0); | |
d7e28ffe RR |
165 | return; |
166 | } | |
167 | ||
b410e7b1 | 168 | if (lguest_arch_init_hypercalls(lg)) |
d7e28ffe | 169 | kill_guest(lg, "bad guest page %p", lg->lguest_data); |
3c6b5bfa | 170 | |
bff672e6 RR |
171 | /* The Guest tells us where we're not to deliver interrupts by putting |
172 | * the range of addresses into "struct lguest_data". */ | |
d7e28ffe | 173 | if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start) |
47436aa4 | 174 | || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)) |
d7e28ffe RR |
175 | kill_guest(lg, "bad guest page %p", lg->lguest_data); |
176 | ||
e1e72965 RR |
177 | /* We write the current time into the Guest's data page once so it can |
178 | * set its clock. */ | |
6c8dca5d RR |
179 | write_timestamp(lg); |
180 | ||
47436aa4 RR |
181 | /* page_tables.c will also do some setup. */ |
182 | page_table_guest_data_init(lg); | |
183 | ||
bff672e6 RR |
184 | /* This is the one case where the above accesses might have been the |
185 | * first write to a Guest page. This may have caused a copy-on-write | |
e1e72965 RR |
186 | * fault, but the old page might be (read-only) in the Guest |
187 | * pagetable. */ | |
d7e28ffe RR |
188 | guest_pagetable_clear_all(lg); |
189 | } | |
190 | ||
bff672e6 RR |
191 | /*H:100 |
192 | * Hypercalls | |
193 | * | |
194 | * Remember from the Guest, hypercalls come in two flavors: normal and | |
195 | * asynchronous. This file handles both of types. | |
196 | */ | |
d7e28ffe RR |
197 | void do_hypercalls(struct lguest *lg) |
198 | { | |
cc6d4fbc | 199 | /* Not initialized yet? This hypercall must do it. */ |
d7e28ffe | 200 | if (unlikely(!lg->lguest_data)) { |
cc6d4fbc RR |
201 | /* Set up the "struct lguest_data" */ |
202 | initialize(lg); | |
203 | /* Hcall is done. */ | |
204 | lg->hcall = NULL; | |
d7e28ffe RR |
205 | return; |
206 | } | |
207 | ||
bff672e6 RR |
208 | /* The Guest has initialized. |
209 | * | |
210 | * Look in the hypercall ring for the async hypercalls: */ | |
d7e28ffe | 211 | do_async_hcalls(lg); |
bff672e6 RR |
212 | |
213 | /* If we stopped reading the hypercall ring because the Guest did a | |
15045275 | 214 | * NOTIFY to the Launcher, we want to return now. Otherwise we do |
cc6d4fbc | 215 | * the hypercall. */ |
15045275 | 216 | if (!lg->pending_notify) { |
cc6d4fbc RR |
217 | do_hcall(lg, lg->hcall); |
218 | /* Tricky point: we reset the hcall pointer to mark the | |
219 | * hypercall as "done". We use the hcall pointer rather than | |
220 | * the trap number to indicate a hypercall is pending. | |
221 | * Normally it doesn't matter: the Guest will run again and | |
222 | * update the trap number before we come back here. | |
223 | * | |
e1e72965 | 224 | * However, if we are signalled or the Guest sends I/O to the |
cc6d4fbc RR |
225 | * Launcher, the run_guest() loop will exit without running the |
226 | * Guest. When it comes back it would try to re-run the | |
227 | * hypercall. */ | |
228 | lg->hcall = NULL; | |
d7e28ffe RR |
229 | } |
230 | } | |
6c8dca5d RR |
231 | |
232 | /* This routine supplies the Guest with time: it's used for wallclock time at | |
233 | * initial boot and as a rough time source if the TSC isn't available. */ | |
234 | void write_timestamp(struct lguest *lg) | |
235 | { | |
236 | struct timespec now; | |
237 | ktime_get_real_ts(&now); | |
891ff65f | 238 | if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec))) |
6c8dca5d RR |
239 | kill_guest(lg, "Writing timestamp"); |
240 | } |