diff options
author | Rusty Russell <rusty@rustcorp.com.au> | 2009-07-30 18:03:45 -0400 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-07-30 02:33:45 -0400 |
commit | 2e04ef76916d1e29a077ea9d0f2003c8fd86724d (patch) | |
tree | 2ff8d625d6e467be9f9f1b67a3674cb6e125e970 /drivers/lguest/hypercalls.c | |
parent | e969fed542cae08cb11d666efac4f7c5d624d09f (diff) |
lguest: fix comment style
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does. And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Diffstat (limited to 'drivers/lguest/hypercalls.c')
-rw-r--r-- | drivers/lguest/hypercalls.c | 141 |
1 files changed, 92 insertions, 49 deletions
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c index c29ffa19cb74..787ab4bc09f0 100644 --- a/drivers/lguest/hypercalls.c +++ b/drivers/lguest/hypercalls.c | |||
@@ -1,8 +1,10 @@ | |||
1 | /*P:500 Just as userspace programs request kernel operations through a system | 1 | /*P:500 |
2 | * Just as userspace programs request kernel operations through a system | ||
2 | * call, the Guest requests Host operations through a "hypercall". You might | 3 | * 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 | * 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 | * 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 | * code is basically a one big switch statement. |
7 | :*/ | ||
6 | 8 | ||
7 | /* Copyright (C) 2006 Rusty Russell IBM Corporation | 9 | /* Copyright (C) 2006 Rusty Russell IBM Corporation |
8 | 10 | ||
@@ -28,30 +30,41 @@ | |||
28 | #include <asm/pgtable.h> | 30 | #include <asm/pgtable.h> |
29 | #include "lg.h" | 31 | #include "lg.h" |
30 | 32 | ||
31 | /*H:120 This is the core hypercall routine: where the Guest gets what it wants. | 33 | /*H:120 |
32 | * Or gets killed. Or, in the case of LHCALL_SHUTDOWN, both. */ | 34 | * This is the core hypercall routine: where the Guest gets what it wants. |
35 | * Or gets killed. Or, in the case of LHCALL_SHUTDOWN, both. | ||
36 | */ | ||
33 | static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) | 37 | static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) |
34 | { | 38 | { |
35 | switch (args->arg0) { | 39 | switch (args->arg0) { |
36 | case LHCALL_FLUSH_ASYNC: | 40 | case LHCALL_FLUSH_ASYNC: |
37 | /* This call does nothing, except by breaking out of the Guest | 41 | /* |
38 | * it makes us process all the asynchronous hypercalls. */ | 42 | * This call does nothing, except by breaking out of the Guest |
43 | * it makes us process all the asynchronous hypercalls. | ||
44 | */ | ||
39 | break; | 45 | break; |
40 | case LHCALL_SEND_INTERRUPTS: | 46 | case LHCALL_SEND_INTERRUPTS: |
41 | /* This call does nothing too, but by breaking out of the Guest | 47 | /* |
42 | * it makes us process any pending interrupts. */ | 48 | * This call does nothing too, but by breaking out of the Guest |
49 | * it makes us process any pending interrupts. | ||
50 | */ | ||
43 | break; | 51 | break; |
44 | case LHCALL_LGUEST_INIT: | 52 | case LHCALL_LGUEST_INIT: |
45 | /* You can't get here unless you're already initialized. Don't | 53 | /* |
46 | * do that. */ | 54 | * You can't get here unless you're already initialized. Don't |
55 | * do that. | ||
56 | */ | ||
47 | kill_guest(cpu, "already have lguest_data"); | 57 | kill_guest(cpu, "already have lguest_data"); |
48 | break; | 58 | break; |
49 | case LHCALL_SHUTDOWN: { | 59 | case LHCALL_SHUTDOWN: { |
50 | /* Shutdown is such a trivial hypercall that we do it in four | ||
51 | * lines right here. */ | ||
52 | char msg[128]; | 60 | char msg[128]; |
53 | /* If the lgread fails, it will call kill_guest() itself; the | 61 | /* |
54 | * kill_guest() with the message will be ignored. */ | 62 | * Shutdown is such a trivial hypercall that we do it in four |
63 | * lines right here. | ||
64 | * | ||
65 | * If the lgread fails, it will call kill_guest() itself; the | ||
66 | * kill_guest() with the message will be ignored. | ||
67 | */ | ||
55 | __lgread(cpu, msg, args->arg1, sizeof(msg)); | 68 | __lgread(cpu, msg, args->arg1, sizeof(msg)); |
56 | msg[sizeof(msg)-1] = '\0'; | 69 | msg[sizeof(msg)-1] = '\0'; |
57 | kill_guest(cpu, "CRASH: %s", msg); | 70 | kill_guest(cpu, "CRASH: %s", msg); |
@@ -60,16 +73,17 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) | |||
60 | break; | 73 | break; |
61 | } | 74 | } |
62 | case LHCALL_FLUSH_TLB: | 75 | case LHCALL_FLUSH_TLB: |
63 | /* FLUSH_TLB comes in two flavors, depending on the | 76 | /* FLUSH_TLB comes in two flavors, depending on the argument: */ |
64 | * argument: */ | ||
65 | if (args->arg1) | 77 | if (args->arg1) |
66 | guest_pagetable_clear_all(cpu); | 78 | guest_pagetable_clear_all(cpu); |
67 | else | 79 | else |
68 | guest_pagetable_flush_user(cpu); | 80 | guest_pagetable_flush_user(cpu); |
69 | break; | 81 | break; |
70 | 82 | ||
71 | /* All these calls simply pass the arguments through to the right | 83 | /* |
72 | * routines. */ | 84 | * All these calls simply pass the arguments through to the right |
85 | * routines. | ||
86 | */ | ||
73 | case LHCALL_NEW_PGTABLE: | 87 | case LHCALL_NEW_PGTABLE: |
74 | guest_new_pagetable(cpu, args->arg1); | 88 | guest_new_pagetable(cpu, args->arg1); |
75 | break; | 89 | break; |
@@ -112,15 +126,16 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) | |||
112 | kill_guest(cpu, "Bad hypercall %li\n", args->arg0); | 126 | kill_guest(cpu, "Bad hypercall %li\n", args->arg0); |
113 | } | 127 | } |
114 | } | 128 | } |
115 | /*:*/ | ||
116 | 129 | ||
117 | /*H:124 Asynchronous hypercalls are easy: we just look in the array in the | 130 | /*H:124 |
131 | * Asynchronous hypercalls are easy: we just look in the array in the | ||
118 | * Guest's "struct lguest_data" to see if any new ones are marked "ready". | 132 | * Guest's "struct lguest_data" to see if any new ones are marked "ready". |
119 | * | 133 | * |
120 | * We are careful to do these in order: obviously we respect the order the | 134 | * We are careful to do these in order: obviously we respect the order the |
121 | * Guest put them in the ring, but we also promise the Guest that they will | 135 | * Guest put them in the ring, but we also promise the Guest that they will |
122 | * happen before any normal hypercall (which is why we check this before | 136 | * happen before any normal hypercall (which is why we check this before |
123 | * checking for a normal hcall). */ | 137 | * checking for a normal hcall). |
138 | */ | ||
124 | static void do_async_hcalls(struct lg_cpu *cpu) | 139 | static void do_async_hcalls(struct lg_cpu *cpu) |
125 | { | 140 | { |
126 | unsigned int i; | 141 | unsigned int i; |
@@ -133,22 +148,28 @@ static void do_async_hcalls(struct lg_cpu *cpu) | |||
133 | /* We process "struct lguest_data"s hcalls[] ring once. */ | 148 | /* We process "struct lguest_data"s hcalls[] ring once. */ |
134 | for (i = 0; i < ARRAY_SIZE(st); i++) { | 149 | for (i = 0; i < ARRAY_SIZE(st); i++) { |
135 | struct hcall_args args; | 150 | struct hcall_args args; |
136 | /* We remember where we were up to from last time. This makes | 151 | /* |
152 | * We remember where we were up to from last time. This makes | ||
137 | * sure that the hypercalls are done in the order the Guest | 153 | * sure that the hypercalls are done in the order the Guest |
138 | * places them in the ring. */ | 154 | * places them in the ring. |
155 | */ | ||
139 | unsigned int n = cpu->next_hcall; | 156 | unsigned int n = cpu->next_hcall; |
140 | 157 | ||
141 | /* 0xFF means there's no call here (yet). */ | 158 | /* 0xFF means there's no call here (yet). */ |
142 | if (st[n] == 0xFF) | 159 | if (st[n] == 0xFF) |
143 | break; | 160 | break; |
144 | 161 | ||
145 | /* OK, we have hypercall. Increment the "next_hcall" cursor, | 162 | /* |
146 | * and wrap back to 0 if we reach the end. */ | 163 | * OK, we have hypercall. Increment the "next_hcall" cursor, |
164 | * and wrap back to 0 if we reach the end. | ||
165 | */ | ||
147 | if (++cpu->next_hcall == LHCALL_RING_SIZE) | 166 | if (++cpu->next_hcall == LHCALL_RING_SIZE) |
148 | cpu->next_hcall = 0; | 167 | cpu->next_hcall = 0; |
149 | 168 | ||
150 | /* Copy the hypercall arguments into a local copy of | 169 | /* |
151 | * the hcall_args struct. */ | 170 | * Copy the hypercall arguments into a local copy of the |
171 | * hcall_args struct. | ||
172 | */ | ||
152 | if (copy_from_user(&args, &cpu->lg->lguest_data->hcalls[n], | 173 | if (copy_from_user(&args, &cpu->lg->lguest_data->hcalls[n], |
153 | sizeof(struct hcall_args))) { | 174 | sizeof(struct hcall_args))) { |
154 | kill_guest(cpu, "Fetching async hypercalls"); | 175 | kill_guest(cpu, "Fetching async hypercalls"); |
@@ -164,19 +185,25 @@ static void do_async_hcalls(struct lg_cpu *cpu) | |||
164 | break; | 185 | break; |
165 | } | 186 | } |
166 | 187 | ||
167 | /* Stop doing hypercalls if they want to notify the Launcher: | 188 | /* |
168 | * it needs to service this first. */ | 189 | * Stop doing hypercalls if they want to notify the Launcher: |
190 | * it needs to service this first. | ||
191 | */ | ||
169 | if (cpu->pending_notify) | 192 | if (cpu->pending_notify) |
170 | break; | 193 | break; |
171 | } | 194 | } |
172 | } | 195 | } |
173 | 196 | ||
174 | /* Last of all, we look at what happens first of all. The very first time the | 197 | /* |
175 | * Guest makes a hypercall, we end up here to set things up: */ | 198 | * Last of all, we look at what happens first of all. The very first time the |
199 | * Guest makes a hypercall, we end up here to set things up: | ||
200 | */ | ||
176 | static void initialize(struct lg_cpu *cpu) | 201 | static void initialize(struct lg_cpu *cpu) |
177 | { | 202 | { |
178 | /* You can't do anything until you're initialized. The Guest knows the | 203 | /* |
179 | * rules, so we're unforgiving here. */ | 204 | * You can't do anything until you're initialized. The Guest knows the |
205 | * rules, so we're unforgiving here. | ||
206 | */ | ||
180 | if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) { | 207 | if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) { |
181 | kill_guest(cpu, "hypercall %li before INIT", cpu->hcall->arg0); | 208 | kill_guest(cpu, "hypercall %li before INIT", cpu->hcall->arg0); |
182 | return; | 209 | return; |
@@ -185,32 +212,40 @@ static void initialize(struct lg_cpu *cpu) | |||
185 | if (lguest_arch_init_hypercalls(cpu)) | 212 | if (lguest_arch_init_hypercalls(cpu)) |
186 | kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); | 213 | kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); |
187 | 214 | ||
188 | /* The Guest tells us where we're not to deliver interrupts by putting | 215 | /* |
189 | * the range of addresses into "struct lguest_data". */ | 216 | * The Guest tells us where we're not to deliver interrupts by putting |
217 | * the range of addresses into "struct lguest_data". | ||
218 | */ | ||
190 | if (get_user(cpu->lg->noirq_start, &cpu->lg->lguest_data->noirq_start) | 219 | if (get_user(cpu->lg->noirq_start, &cpu->lg->lguest_data->noirq_start) |
191 | || get_user(cpu->lg->noirq_end, &cpu->lg->lguest_data->noirq_end)) | 220 | || get_user(cpu->lg->noirq_end, &cpu->lg->lguest_data->noirq_end)) |
192 | kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); | 221 | kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); |
193 | 222 | ||
194 | /* We write the current time into the Guest's data page once so it can | 223 | /* |
195 | * set its clock. */ | 224 | * We write the current time into the Guest's data page once so it can |
225 | * set its clock. | ||
226 | */ | ||
196 | write_timestamp(cpu); | 227 | write_timestamp(cpu); |
197 | 228 | ||
198 | /* page_tables.c will also do some setup. */ | 229 | /* page_tables.c will also do some setup. */ |
199 | page_table_guest_data_init(cpu); | 230 | page_table_guest_data_init(cpu); |
200 | 231 | ||
201 | /* This is the one case where the above accesses might have been the | 232 | /* |
233 | * This is the one case where the above accesses might have been the | ||
202 | * first write to a Guest page. This may have caused a copy-on-write | 234 | * first write to a Guest page. This may have caused a copy-on-write |
203 | * fault, but the old page might be (read-only) in the Guest | 235 | * fault, but the old page might be (read-only) in the Guest |
204 | * pagetable. */ | 236 | * pagetable. |
237 | */ | ||
205 | guest_pagetable_clear_all(cpu); | 238 | guest_pagetable_clear_all(cpu); |
206 | } | 239 | } |
207 | /*:*/ | 240 | /*:*/ |
208 | 241 | ||
209 | /*M:013 If a Guest reads from a page (so creates a mapping) that it has never | 242 | /*M:013 |
243 | * If a Guest reads from a page (so creates a mapping) that it has never | ||
210 | * written to, and then the Launcher writes to it (ie. the output of a virtual | 244 | * written to, and then the Launcher writes to it (ie. the output of a virtual |
211 | * device), the Guest will still see the old page. In practice, this never | 245 | * device), the Guest will still see the old page. In practice, this never |
212 | * happens: why would the Guest read a page which it has never written to? But | 246 | * happens: why would the Guest read a page which it has never written to? But |
213 | * a similar scenario might one day bite us, so it's worth mentioning. :*/ | 247 | * a similar scenario might one day bite us, so it's worth mentioning. |
248 | :*/ | ||
214 | 249 | ||
215 | /*H:100 | 250 | /*H:100 |
216 | * Hypercalls | 251 | * Hypercalls |
@@ -229,17 +264,22 @@ void do_hypercalls(struct lg_cpu *cpu) | |||
229 | return; | 264 | return; |
230 | } | 265 | } |
231 | 266 | ||
232 | /* The Guest has initialized. | 267 | /* |
268 | * The Guest has initialized. | ||
233 | * | 269 | * |
234 | * Look in the hypercall ring for the async hypercalls: */ | 270 | * Look in the hypercall ring for the async hypercalls: |
271 | */ | ||
235 | do_async_hcalls(cpu); | 272 | do_async_hcalls(cpu); |
236 | 273 | ||
237 | /* If we stopped reading the hypercall ring because the Guest did a | 274 | /* |
275 | * If we stopped reading the hypercall ring because the Guest did a | ||
238 | * NOTIFY to the Launcher, we want to return now. Otherwise we do | 276 | * NOTIFY to the Launcher, we want to return now. Otherwise we do |
239 | * the hypercall. */ | 277 | * the hypercall. |
278 | */ | ||
240 | if (!cpu->pending_notify) { | 279 | if (!cpu->pending_notify) { |
241 | do_hcall(cpu, cpu->hcall); | 280 | do_hcall(cpu, cpu->hcall); |
242 | /* Tricky point: we reset the hcall pointer to mark the | 281 | /* |
282 | * Tricky point: we reset the hcall pointer to mark the | ||
243 | * hypercall as "done". We use the hcall pointer rather than | 283 | * hypercall as "done". We use the hcall pointer rather than |
244 | * the trap number to indicate a hypercall is pending. | 284 | * the trap number to indicate a hypercall is pending. |
245 | * Normally it doesn't matter: the Guest will run again and | 285 | * Normally it doesn't matter: the Guest will run again and |
@@ -248,13 +288,16 @@ void do_hypercalls(struct lg_cpu *cpu) | |||
248 | * However, if we are signalled or the Guest sends I/O to the | 288 | * However, if we are signalled or the Guest sends I/O to the |
249 | * Launcher, the run_guest() loop will exit without running the | 289 | * Launcher, the run_guest() loop will exit without running the |
250 | * Guest. When it comes back it would try to re-run the | 290 | * Guest. When it comes back it would try to re-run the |
251 | * hypercall. Finding that bug sucked. */ | 291 | * hypercall. Finding that bug sucked. |
292 | */ | ||
252 | cpu->hcall = NULL; | 293 | cpu->hcall = NULL; |
253 | } | 294 | } |
254 | } | 295 | } |
255 | 296 | ||
256 | /* This routine supplies the Guest with time: it's used for wallclock time at | 297 | /* |
257 | * initial boot and as a rough time source if the TSC isn't available. */ | 298 | * This routine supplies the Guest with time: it's used for wallclock time at |
299 | * initial boot and as a rough time source if the TSC isn't available. | ||
300 | */ | ||
258 | void write_timestamp(struct lg_cpu *cpu) | 301 | void write_timestamp(struct lg_cpu *cpu) |
259 | { | 302 | { |
260 | struct timespec now; | 303 | struct timespec now; |