Rusty Russell | f938d2c | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 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 |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 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> |
| 28 | #include <irq_vectors.h> |
| 29 | #include "lg.h" |
| 30 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 31 | /*H:120 This is the core hypercall routine: where the Guest gets what it |
| 32 | * wants. Or gets killed. Or, in the case of LHCALL_CRASH, both. |
| 33 | * |
| 34 | * Remember from the Guest: %eax == which call to make, and the arguments are |
| 35 | * packed into %edx, %ebx and %ecx if needed. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 36 | static void do_hcall(struct lguest *lg, struct lguest_regs *regs) |
| 37 | { |
| 38 | switch (regs->eax) { |
| 39 | case LHCALL_FLUSH_ASYNC: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 40 | /* This call does nothing, except by breaking out of the Guest |
| 41 | * it makes us process all the asynchronous hypercalls. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 42 | break; |
| 43 | case LHCALL_LGUEST_INIT: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 44 | /* You can't get here unless you're already initialized. Don't |
| 45 | * do that. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 46 | kill_guest(lg, "already have lguest_data"); |
| 47 | break; |
| 48 | case LHCALL_CRASH: { |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 49 | /* Crash is such a trivial hypercall that we do it in four |
| 50 | * lines right here. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 51 | char msg[128]; |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 52 | /* If the lgread fails, it will call kill_guest() itself; the |
| 53 | * kill_guest() with the message will be ignored. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 54 | lgread(lg, msg, regs->edx, sizeof(msg)); |
| 55 | msg[sizeof(msg)-1] = '\0'; |
| 56 | kill_guest(lg, "CRASH: %s", msg); |
| 57 | break; |
| 58 | } |
| 59 | case LHCALL_FLUSH_TLB: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 60 | /* FLUSH_TLB comes in two flavors, depending on the |
| 61 | * argument: */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 62 | if (regs->edx) |
| 63 | guest_pagetable_clear_all(lg); |
| 64 | else |
| 65 | guest_pagetable_flush_user(lg); |
| 66 | break; |
| 67 | case LHCALL_GET_WALLCLOCK: { |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 68 | /* The Guest wants to know the real time in seconds since 1970, |
| 69 | * in good Unix tradition. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 70 | struct timespec ts; |
| 71 | ktime_get_real_ts(&ts); |
| 72 | regs->eax = ts.tv_sec; |
| 73 | break; |
| 74 | } |
| 75 | case LHCALL_BIND_DMA: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 76 | /* BIND_DMA really wants four arguments, but it's the only call |
| 77 | * which does. So the Guest packs the number of buffers and |
| 78 | * the interrupt number into the final argument, and we decode |
| 79 | * it here. This can legitimately fail, since we currently |
| 80 | * place a limit on the number of DMA pools a Guest can have. |
| 81 | * So we return true or false from this call. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 82 | regs->eax = bind_dma(lg, regs->edx, regs->ebx, |
| 83 | regs->ecx >> 8, regs->ecx & 0xFF); |
| 84 | break; |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 85 | |
| 86 | /* All these calls simply pass the arguments through to the right |
| 87 | * routines. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 88 | case LHCALL_SEND_DMA: |
| 89 | send_dma(lg, regs->edx, regs->ebx); |
| 90 | break; |
| 91 | case LHCALL_LOAD_GDT: |
| 92 | load_guest_gdt(lg, regs->edx, regs->ebx); |
| 93 | break; |
| 94 | case LHCALL_LOAD_IDT_ENTRY: |
| 95 | load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx); |
| 96 | break; |
| 97 | case LHCALL_NEW_PGTABLE: |
| 98 | guest_new_pagetable(lg, regs->edx); |
| 99 | break; |
| 100 | case LHCALL_SET_STACK: |
| 101 | guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx); |
| 102 | break; |
| 103 | case LHCALL_SET_PTE: |
| 104 | guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx)); |
| 105 | break; |
| 106 | case LHCALL_SET_PMD: |
| 107 | guest_set_pmd(lg, regs->edx, regs->ebx); |
| 108 | break; |
| 109 | case LHCALL_LOAD_TLS: |
| 110 | guest_load_tls(lg, regs->edx); |
| 111 | break; |
| 112 | case LHCALL_SET_CLOCKEVENT: |
| 113 | guest_set_clockevent(lg, regs->edx); |
| 114 | break; |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 115 | |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 116 | case LHCALL_TS: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 117 | /* This sets the TS flag, as we saw used in run_guest(). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 118 | lg->ts = regs->edx; |
| 119 | break; |
| 120 | case LHCALL_HALT: |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 121 | /* Similarly, this sets the halted flag for run_guest(). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 122 | lg->halted = 1; |
| 123 | break; |
| 124 | default: |
| 125 | kill_guest(lg, "Bad hypercall %li\n", regs->eax); |
| 126 | } |
| 127 | } |
| 128 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 129 | /* Asynchronous hypercalls are easy: we just look in the array in the Guest's |
| 130 | * "struct lguest_data" and see if there are any new ones marked "ready". |
| 131 | * |
| 132 | * We are careful to do these in order: obviously we respect the order the |
| 133 | * Guest put them in the ring, but we also promise the Guest that they will |
| 134 | * happen before any normal hypercall (which is why we check this before |
| 135 | * checking for a normal hcall). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 136 | static void do_async_hcalls(struct lguest *lg) |
| 137 | { |
| 138 | unsigned int i; |
| 139 | u8 st[LHCALL_RING_SIZE]; |
| 140 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 141 | /* For simplicity, we copy the entire call status array in at once. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 142 | if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st))) |
| 143 | return; |
| 144 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 145 | |
| 146 | /* We process "struct lguest_data"s hcalls[] ring once. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 147 | for (i = 0; i < ARRAY_SIZE(st); i++) { |
| 148 | struct lguest_regs regs; |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 149 | /* We remember where we were up to from last time. This makes |
| 150 | * sure that the hypercalls are done in the order the Guest |
| 151 | * places them in the ring. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 152 | unsigned int n = lg->next_hcall; |
| 153 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 154 | /* 0xFF means there's no call here (yet). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 155 | if (st[n] == 0xFF) |
| 156 | break; |
| 157 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 158 | /* OK, we have hypercall. Increment the "next_hcall" cursor, |
| 159 | * and wrap back to 0 if we reach the end. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 160 | if (++lg->next_hcall == LHCALL_RING_SIZE) |
| 161 | lg->next_hcall = 0; |
| 162 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 163 | /* We copy the hypercall arguments into a fake register |
| 164 | * structure. This makes life simple for do_hcall(). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 165 | if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax) |
| 166 | || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx) |
| 167 | || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx) |
| 168 | || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) { |
| 169 | kill_guest(lg, "Fetching async hypercalls"); |
| 170 | break; |
| 171 | } |
| 172 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 173 | /* Do the hypercall, same as a normal one. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 174 | do_hcall(lg, ®s); |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 175 | |
| 176 | /* Mark the hypercall done. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 177 | if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) { |
| 178 | kill_guest(lg, "Writing result for async hypercall"); |
| 179 | break; |
| 180 | } |
| 181 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 182 | /* Stop doing hypercalls if we've just done a DMA to the |
| 183 | * Launcher: it needs to service this first. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 184 | if (lg->dma_is_pending) |
| 185 | break; |
| 186 | } |
| 187 | } |
| 188 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 189 | /* Last of all, we look at what happens first of all. The very first time the |
| 190 | * Guest makes a hypercall, we end up here to set things up: */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 191 | static void initialize(struct lguest *lg) |
| 192 | { |
| 193 | u32 tsc_speed; |
| 194 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 195 | /* You can't do anything until you're initialized. The Guest knows the |
| 196 | * rules, so we're unforgiving here. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 197 | if (lg->regs->eax != LHCALL_LGUEST_INIT) { |
| 198 | kill_guest(lg, "hypercall %li before LGUEST_INIT", |
| 199 | lg->regs->eax); |
| 200 | return; |
| 201 | } |
| 202 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 203 | /* We insist that the Time Stamp Counter exist and doesn't change with |
| 204 | * cpu frequency. Some devious chip manufacturers decided that TSC |
| 205 | * changes could be handled in software. I decided that time going |
| 206 | * backwards might be good for benchmarks, but it's bad for users. |
| 207 | * |
| 208 | * We also insist that the TSC be stable: the kernel detects unreliable |
| 209 | * TSCs for its own purposes, and we use that here. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 210 | if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable()) |
| 211 | tsc_speed = tsc_khz; |
| 212 | else |
| 213 | tsc_speed = 0; |
| 214 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 215 | /* The pointer to the Guest's "struct lguest_data" is the only |
| 216 | * argument. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 217 | lg->lguest_data = (struct lguest_data __user *)lg->regs->edx; |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 218 | /* If we check the address they gave is OK now, we can simply |
| 219 | * copy_to_user/from_user from now on rather than using lgread/lgwrite. |
| 220 | * I put this in to show that I'm not immune to writing stupid |
| 221 | * optimizations. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 222 | if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) { |
| 223 | kill_guest(lg, "bad guest page %p", lg->lguest_data); |
| 224 | return; |
| 225 | } |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 226 | /* The Guest tells us where we're not to deliver interrupts by putting |
| 227 | * the range of addresses into "struct lguest_data". */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 228 | if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start) |
| 229 | || get_user(lg->noirq_end, &lg->lguest_data->noirq_end) |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 230 | /* We tell the Guest that it can't use the top 4MB of virtual |
| 231 | * addresses used by the Switcher. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 232 | || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem) |
| 233 | || put_user(tsc_speed, &lg->lguest_data->tsc_khz) |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 234 | /* We also give the Guest a unique id, as used in lguest_net.c. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 235 | || put_user(lg->guestid, &lg->lguest_data->guestid)) |
| 236 | kill_guest(lg, "bad guest page %p", lg->lguest_data); |
| 237 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 238 | /* This is the one case where the above accesses might have been the |
| 239 | * first write to a Guest page. This may have caused a copy-on-write |
| 240 | * fault, but the Guest might be referring to the old (read-only) |
| 241 | * page. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 242 | guest_pagetable_clear_all(lg); |
| 243 | } |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 244 | /* Now we've examined the hypercall code; our Guest can make requests. There |
| 245 | * is one other way we can do things for the Guest, as we see in |
| 246 | * emulate_insn(). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 247 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 248 | /*H:110 Tricky point: we mark the hypercall as "done" once we've done it. |
| 249 | * Normally we don't need to do this: the Guest will run again and update the |
| 250 | * trap number before we come back around the run_guest() loop to |
| 251 | * do_hypercalls(). |
| 252 | * |
| 253 | * However, if we are signalled or the Guest sends DMA to the Launcher, that |
| 254 | * loop will exit without running the Guest. When it comes back it would try |
| 255 | * to re-run the hypercall. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 256 | static void clear_hcall(struct lguest *lg) |
| 257 | { |
| 258 | lg->regs->trapnum = 255; |
| 259 | } |
| 260 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 261 | /*H:100 |
| 262 | * Hypercalls |
| 263 | * |
| 264 | * Remember from the Guest, hypercalls come in two flavors: normal and |
| 265 | * asynchronous. This file handles both of types. |
| 266 | */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 267 | void do_hypercalls(struct lguest *lg) |
| 268 | { |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 269 | /* Not initialized yet? */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 270 | if (unlikely(!lg->lguest_data)) { |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 271 | /* Did the Guest make a hypercall? We might have come back for |
| 272 | * some other reason (an interrupt, a different trap). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 273 | if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) { |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 274 | /* Set up the "struct lguest_data" */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 275 | initialize(lg); |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 276 | /* The hypercall is done. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 277 | clear_hcall(lg); |
| 278 | } |
| 279 | return; |
| 280 | } |
| 281 | |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 282 | /* The Guest has initialized. |
| 283 | * |
| 284 | * Look in the hypercall ring for the async hypercalls: */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 285 | do_async_hcalls(lg); |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 286 | |
| 287 | /* If we stopped reading the hypercall ring because the Guest did a |
| 288 | * SEND_DMA to the Launcher, we want to return now. Otherwise if the |
| 289 | * Guest asked us to do a hypercall, we do it. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 290 | if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) { |
| 291 | do_hcall(lg, lg->regs); |
Rusty Russell | bff672e | 2007-07-26 10:41:04 -0700 | [diff] [blame^] | 292 | /* The hypercall is done. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 293 | clear_hcall(lg); |
| 294 | } |
| 295 | } |