-/*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
#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_GET_WALLCLOCK: {
- /* The Guest wants to know the real time in seconds since 1970,
- * in good Unix tradition. */
- struct timespec ts;
- ktime_get_real_ts(&ts);
- regs->eax = ts.tv_sec;
- 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 so it can
+ * set its clock.
+ */
+ write_timestamp(cpu);
+
+ /* 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
+ /*
+ * 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
* 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 lg_cpu *cpu)
+{
+ struct timespec now;
+ ktime_get_real_ts(&now);
+ if (copy_to_user(&cpu->lg->lguest_data->time,
+ &now, sizeof(struct timespec)))
+ kill_guest(cpu, "Writing timestamp");
+}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff