diff options
Diffstat (limited to 'drivers/lguest/hypercalls.c')
| -rw-r--r-- | drivers/lguest/hypercalls.c | 364 |
1 files changed, 188 insertions, 176 deletions
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c index db6caace3b9..83511eb0923 100644 --- a/drivers/lguest/hypercalls.c +++ b/drivers/lguest/hypercalls.c @@ -1,8 +1,10 @@ -/*P:500 Just as userspace programs request kernel operations through a system +/*P:500 + * Just as userspace programs request kernel operations through a system * call, the Guest requests Host operations through a "hypercall". You might * notice this nomenclature doesn't really follow any logic, but the name has * been around for long enough that we're stuck with it. As you'd expect, this - * code is basically a one big switch statement. :*/ + * code is basically a one big switch statement. +:*/ /* Copyright (C) 2006 Rusty Russell IBM Corporation @@ -23,235 +25,231 @@ #include <linux/uaccess.h> #include <linux/syscalls.h> #include <linux/mm.h> +#include <linux/ktime.h> #include <asm/page.h> #include <asm/pgtable.h> -#include <irq_vectors.h> #include "lg.h" -/*H:120 This is the core hypercall routine: where the Guest gets what it - * wants. Or gets killed. Or, in the case of LHCALL_CRASH, both. - * - * Remember from the Guest: %eax == which call to make, and the arguments are - * packed into %edx, %ebx and %ecx if needed. */ -static void do_hcall(struct lguest *lg, struct lguest_regs *regs) +/*H:120 + * This is the core hypercall routine: where the Guest gets what it wants. + * Or gets killed. Or, in the case of LHCALL_SHUTDOWN, both. + */ +static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) { - switch (regs->eax) { + switch (args->arg0) { case LHCALL_FLUSH_ASYNC: - /* This call does nothing, except by breaking out of the Guest - * it makes us process all the asynchronous hypercalls. */ + /* + * This call does nothing, except by breaking out of the Guest + * it makes us process all the asynchronous hypercalls. + */ + break; + case LHCALL_SEND_INTERRUPTS: + /* + * This call does nothing too, but by breaking out of the Guest + * it makes us process any pending interrupts. + */ break; case LHCALL_LGUEST_INIT: - /* You can't get here unless you're already initialized. Don't - * do that. */ - kill_guest(lg, "already have lguest_data"); + /* + * You can't get here unless you're already initialized. Don't + * do that. + */ + kill_guest(cpu, "already have lguest_data"); break; - case LHCALL_CRASH: { - /* Crash is such a trivial hypercall that we do it in four - * lines right here. */ + case LHCALL_SHUTDOWN: { char msg[128]; - /* If the lgread fails, it will call kill_guest() itself; the - * kill_guest() with the message will be ignored. */ - lgread(lg, msg, regs->edx, sizeof(msg)); + /* + * Shutdown is such a trivial hypercall that we do it in five + * lines right here. + * + * If the lgread fails, it will call kill_guest() itself; the + * kill_guest() with the message will be ignored. + */ + __lgread(cpu, msg, args->arg1, sizeof(msg)); msg[sizeof(msg)-1] = '\0'; - kill_guest(lg, "CRASH: %s", msg); + kill_guest(cpu, "CRASH: %s", msg); + if (args->arg2 == LGUEST_SHUTDOWN_RESTART) + cpu->lg->dead = ERR_PTR(-ERESTART); break; } case LHCALL_FLUSH_TLB: - /* FLUSH_TLB comes in two flavors, depending on the - * argument: */ - if (regs->edx) - guest_pagetable_clear_all(lg); + /* FLUSH_TLB comes in two flavors, depending on the argument: */ + if (args->arg1) + guest_pagetable_clear_all(cpu); else - guest_pagetable_flush_user(lg); - break; - case LHCALL_BIND_DMA: - /* BIND_DMA really wants four arguments, but it's the only call - * which does. So the Guest packs the number of buffers and - * the interrupt number into the final argument, and we decode - * it here. This can legitimately fail, since we currently - * place a limit on the number of DMA pools a Guest can have. - * So we return true or false from this call. */ - regs->eax = bind_dma(lg, regs->edx, regs->ebx, - regs->ecx >> 8, regs->ecx & 0xFF); + guest_pagetable_flush_user(cpu); break; - /* All these calls simply pass the arguments through to the right - * routines. */ - case LHCALL_SEND_DMA: - send_dma(lg, regs->edx, regs->ebx); - break; - case LHCALL_LOAD_GDT: - load_guest_gdt(lg, regs->edx, regs->ebx); - break; - case LHCALL_LOAD_IDT_ENTRY: - load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx); - break; + /* + * All these calls simply pass the arguments through to the right + * routines. + */ case LHCALL_NEW_PGTABLE: - guest_new_pagetable(lg, regs->edx); + guest_new_pagetable(cpu, args->arg1); break; case LHCALL_SET_STACK: - guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx); + guest_set_stack(cpu, args->arg1, args->arg2, args->arg3); break; case LHCALL_SET_PTE: - guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx)); +#ifdef CONFIG_X86_PAE + guest_set_pte(cpu, args->arg1, args->arg2, + __pte(args->arg3 | (u64)args->arg4 << 32)); +#else + guest_set_pte(cpu, args->arg1, args->arg2, __pte(args->arg3)); +#endif break; - case LHCALL_SET_PMD: - guest_set_pmd(lg, regs->edx, regs->ebx); + case LHCALL_SET_PGD: + guest_set_pgd(cpu->lg, args->arg1, args->arg2); break; - case LHCALL_LOAD_TLS: - guest_load_tls(lg, regs->edx); +#ifdef CONFIG_X86_PAE + case LHCALL_SET_PMD: + guest_set_pmd(cpu->lg, args->arg1, args->arg2); break; +#endif case LHCALL_SET_CLOCKEVENT: - guest_set_clockevent(lg, regs->edx); + guest_set_clockevent(cpu, args->arg1); break; - case LHCALL_TS: /* This sets the TS flag, as we saw used in run_guest(). */ - lg->ts = regs->edx; + cpu->ts = args->arg1; break; case LHCALL_HALT: /* Similarly, this sets the halted flag for run_guest(). */ - lg->halted = 1; + cpu->halted = 1; + break; + case LHCALL_NOTIFY: + cpu->pending_notify = args->arg1; break; default: - kill_guest(lg, "Bad hypercall %li\n", regs->eax); + /* It should be an architecture-specific hypercall. */ + if (lguest_arch_do_hcall(cpu, args)) + kill_guest(cpu, "Bad hypercall %li\n", args->arg0); } } -/* Asynchronous hypercalls are easy: we just look in the array in the Guest's - * "struct lguest_data" and see if there are any new ones marked "ready". +/*H:124 + * Asynchronous hypercalls are easy: we just look in the array in the + * Guest's "struct lguest_data" to see if any new ones are marked "ready". * * We are careful to do these in order: obviously we respect the order the * Guest put them in the ring, but we also promise the Guest that they will * happen before any normal hypercall (which is why we check this before - * checking for a normal hcall). */ -static void do_async_hcalls(struct lguest *lg) + * checking for a normal hcall). + */ +static void do_async_hcalls(struct lg_cpu *cpu) { unsigned int i; u8 st[LHCALL_RING_SIZE]; /* For simplicity, we copy the entire call status array in at once. */ - if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st))) + if (copy_from_user(&st, &cpu->lg->lguest_data->hcall_status, sizeof(st))) return; - /* We process "struct lguest_data"s hcalls[] ring once. */ for (i = 0; i < ARRAY_SIZE(st); i++) { - struct lguest_regs regs; - /* We remember where we were up to from last time. This makes + struct hcall_args args; + /* + * We remember where we were up to from last time. This makes * sure that the hypercalls are done in the order the Guest - * places them in the ring. */ - unsigned int n = lg->next_hcall; + * places them in the ring. + */ + unsigned int n = cpu->next_hcall; /* 0xFF means there's no call here (yet). */ if (st[n] == 0xFF) break; - /* OK, we have hypercall. Increment the "next_hcall" cursor, - * and wrap back to 0 if we reach the end. */ - if (++lg->next_hcall == LHCALL_RING_SIZE) - lg->next_hcall = 0; + /* + * OK, we have hypercall. Increment the "next_hcall" cursor, + * and wrap back to 0 if we reach the end. + */ + if (++cpu->next_hcall == LHCALL_RING_SIZE) + cpu->next_hcall = 0; - /* We copy the hypercall arguments into a fake register - * structure. This makes life simple for do_hcall(). */ - if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax) - || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx) - || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx) - || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) { - kill_guest(lg, "Fetching async hypercalls"); + /* + * Copy the hypercall arguments into a local copy of the + * hcall_args struct. + */ + if (copy_from_user(&args, &cpu->lg->lguest_data->hcalls[n], + sizeof(struct hcall_args))) { + kill_guest(cpu, "Fetching async hypercalls"); break; } /* Do the hypercall, same as a normal one. */ - do_hcall(lg, ®s); + do_hcall(cpu, &args); /* Mark the hypercall done. */ - if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) { - kill_guest(lg, "Writing result for async hypercall"); + if (put_user(0xFF, &cpu->lg->lguest_data->hcall_status[n])) { + kill_guest(cpu, "Writing result for async hypercall"); break; } - /* Stop doing hypercalls if we've just done a DMA to the - * Launcher: it needs to service this first. */ - if (lg->dma_is_pending) + /* + * Stop doing hypercalls if they want to notify the Launcher: + * it needs to service this first. + */ + if (cpu->pending_notify) break; } } -/* Last of all, we look at what happens first of all. The very first time the - * Guest makes a hypercall, we end up here to set things up: */ -static void initialize(struct lguest *lg) +/* + * Last of all, we look at what happens first of all. The very first time the + * Guest makes a hypercall, we end up here to set things up: + */ +static void initialize(struct lg_cpu *cpu) { - u32 tsc_speed; - - /* You can't do anything until you're initialized. The Guest knows the - * rules, so we're unforgiving here. */ - if (lg->regs->eax != LHCALL_LGUEST_INIT) { - kill_guest(lg, "hypercall %li before LGUEST_INIT", - lg->regs->eax); + /* + * You can't do anything until you're initialized. The Guest knows the + * rules, so we're unforgiving here. + */ + if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) { + kill_guest(cpu, "hypercall %li before INIT", cpu->hcall->arg0); return; } - /* We insist that the Time Stamp Counter exist and doesn't change with - * cpu frequency. Some devious chip manufacturers decided that TSC - * changes could be handled in software. I decided that time going - * backwards might be good for benchmarks, but it's bad for users. - * - * We also insist that the TSC be stable: the kernel detects unreliable - * TSCs for its own purposes, and we use that here. */ - if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable()) - tsc_speed = tsc_khz; - else - tsc_speed = 0; + if (lguest_arch_init_hypercalls(cpu)) + kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); - /* The pointer to the Guest's "struct lguest_data" is the only - * argument. */ - lg->lguest_data = (struct lguest_data __user *)lg->regs->edx; - /* If we check the address they gave is OK now, we can simply - * copy_to_user/from_user from now on rather than using lgread/lgwrite. - * I put this in to show that I'm not immune to writing stupid - * optimizations. */ - if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) { - kill_guest(lg, "bad guest page %p", lg->lguest_data); - return; - } - /* The Guest tells us where we're not to deliver interrupts by putting - * the range of addresses into "struct lguest_data". */ - if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start) - || get_user(lg->noirq_end, &lg->lguest_data->noirq_end) - /* We tell the Guest that it can't use the top 4MB of virtual - * addresses used by the Switcher. */ - || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem) - || put_user(tsc_speed, &lg->lguest_data->tsc_khz) - /* We also give the Guest a unique id, as used in lguest_net.c. */ - || put_user(lg->guestid, &lg->lguest_data->guestid)) - kill_guest(lg, "bad guest page %p", lg->lguest_data); + /* + * The Guest tells us where we're not to deliver interrupts by putting + * the range of addresses into "struct lguest_data". + */ + if (get_user(cpu->lg->noirq_start, &cpu->lg->lguest_data->noirq_start) + || get_user(cpu->lg->noirq_end, &cpu->lg->lguest_data->noirq_end)) + kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); - /* We write the current time into the Guest's data page once now. */ - write_timestamp(lg); + /* + * We write the current time into the Guest's data page once so it can + * set its clock. + */ + write_timestamp(cpu); - /* This is the one case where the above accesses might have been the + /* page_tables.c will also do some setup. */ + page_table_guest_data_init(cpu); + + /* + * This is the one case where the above accesses might have been the * first write to a Guest page. This may have caused a copy-on-write - * fault, but the Guest might be referring to the old (read-only) - * page. */ - guest_pagetable_clear_all(lg); + * fault, but the old page might be (read-only) in the Guest + * pagetable. + */ + guest_pagetable_clear_all(cpu); } -/* Now we've examined the hypercall code; our Guest can make requests. There - * is one other way we can do things for the Guest, as we see in - * emulate_insn(). */ +/*:*/ -/*H:110 Tricky point: we mark the hypercall as "done" once we've done it. - * Normally we don't need to do this: the Guest will run again and update the - * trap number before we come back around the run_guest() loop to - * do_hypercalls(). +/*M:013 + * If a Guest reads from a page (so creates a mapping) that it has never + * written to, and then the Launcher writes to it (ie. the output of a virtual + * device), the Guest will still see the old page. In practice, this never + * happens: why would the Guest read a page which it has never written to? But + * a similar scenario might one day bite us, so it's worth mentioning. * - * However, if we are signalled or the Guest sends DMA to the Launcher, that - * loop will exit without running the Guest. When it comes back it would try - * to re-run the hypercall. */ -static void clear_hcall(struct lguest *lg) -{ - lg->regs->trapnum = 255; -} + * Note that if we used a shared anonymous mapping in the Launcher instead of + * mapping /dev/zero private, we wouldn't worry about cop-on-write. And we + * need that to switch the Launcher to processes (away from threads) anyway. +:*/ /*H:100 * Hypercalls @@ -259,42 +257,56 @@ static void clear_hcall(struct lguest *lg) * Remember from the Guest, hypercalls come in two flavors: normal and * asynchronous. This file handles both of types. */ -void do_hypercalls(struct lguest *lg) +void do_hypercalls(struct lg_cpu *cpu) { - /* Not initialized yet? */ - if (unlikely(!lg->lguest_data)) { - /* Did the Guest make a hypercall? We might have come back for - * some other reason (an interrupt, a different trap). */ - if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) { - /* Set up the "struct lguest_data" */ - initialize(lg); - /* The hypercall is done. */ - clear_hcall(lg); - } + /* Not initialized yet? This hypercall must do it. */ + if (unlikely(!cpu->lg->lguest_data)) { + /* Set up the "struct lguest_data" */ + initialize(cpu); + /* Hcall is done. */ + cpu->hcall = NULL; return; } - /* The Guest has initialized. + /* + * The Guest has initialized. * - * Look in the hypercall ring for the async hypercalls: */ - do_async_hcalls(lg); + * Look in the hypercall ring for the async hypercalls: + */ + do_async_hcalls(cpu); - /* If we stopped reading the hypercall ring because the Guest did a - * SEND_DMA to the Launcher, we want to return now. Otherwise if the - * Guest asked us to do a hypercall, we do it. */ - if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) { - do_hcall(lg, lg->regs); - /* The hypercall is done. */ - clear_hcall(lg); + /* + * If we stopped reading the hypercall ring because the Guest did a + * NOTIFY to the Launcher, we want to return now. Otherwise we do + * the hypercall. + */ + if (!cpu->pending_notify) { + do_hcall(cpu, cpu->hcall); + /* + * Tricky point: we reset the hcall pointer to mark the + * hypercall as "done". We use the hcall pointer rather than + * the trap number to indicate a hypercall is pending. + * Normally it doesn't matter: the Guest will run again and + * update the trap number before we come back here. + * + * However, if we are signalled or the Guest sends I/O to the + * Launcher, the run_guest() loop will exit without running the + * Guest. When it comes back it would try to re-run the + * hypercall. Finding that bug sucked. + */ + cpu->hcall = NULL; } } -/* This routine supplies the Guest with time: it's used for wallclock time at - * initial boot and as a rough time source if the TSC isn't available. */ -void write_timestamp(struct lguest *lg) +/* + * This routine supplies the Guest with time: it's used for wallclock time at + * initial boot and as a rough time source if the TSC isn't available. + */ +void write_timestamp(struct lg_cpu *cpu) { struct timespec now; ktime_get_real_ts(&now); - if (put_user(now, &lg->lguest_data->time)) - kill_guest(lg, "Writing timestamp"); + if (copy_to_user(&cpu->lg->lguest_data->time, + &now, sizeof(struct timespec))) + kill_guest(cpu, "Writing timestamp"); } |