-/*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 <asm/pgtable.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_SHUTDOWN, both. */
+/*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 (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. */
+ /*
+ * 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. */
+ /*
+ * You can't get here unless you're already initialized. Don't
+ * do that.
+ */
kill_guest(cpu, "already have lguest_data");
break;
case LHCALL_SHUTDOWN: {
- /* Shutdown is such a trivial hypercall that we do it in four
- * lines right here. */
char msg[128];
- /* If the lgread fails, it will call kill_guest() itself; the
- * kill_guest() with the message will be ignored. */
+ /*
+ * 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(cpu, "CRASH: %s", msg);
break;
}
case LHCALL_FLUSH_TLB:
- /* FLUSH_TLB comes in two flavors, depending on the
- * argument: */
+ /* FLUSH_TLB comes in two flavors, depending on the argument: */
if (args->arg1)
guest_pagetable_clear_all(cpu);
else
guest_pagetable_flush_user(cpu);
break;
- /* All these calls simply pass the arguments through to the right
- * routines. */
+ /*
+ * All these calls simply pass the arguments through to the right
+ * routines.
+ */
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(cpu, args->arg1);
break;
kill_guest(cpu, "Bad hypercall %li\n", args->arg0);
}
}
-/*:*/
-/*H:124 Asynchronous hypercalls are easy: we just look in the array in the
+/*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). */
+ * checking for a normal hcall).
+ */
static void do_async_hcalls(struct lg_cpu *cpu)
{
unsigned int i;
/* We process "struct lguest_data"s hcalls[] ring once. */
for (i = 0; i < ARRAY_SIZE(st); i++) {
struct hcall_args args;
- /* We remember where we were up to from last time. This makes
+ /*
+ * 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. */
+ * 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. */
+ /*
+ * 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;
- /* Copy the hypercall arguments into a local copy of
- * the hcall_args struct. */
+ /*
+ * 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;
}
- /* Stop doing hypercalls if they want to notify the Launcher:
- * it needs to service this first. */
+ /*
+ * 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: */
+/*
+ * 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)
{
- /* You can't do anything until you're initialized. The Guest knows the
- * rules, so we're unforgiving here. */
+ /*
+ * 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;
if (lguest_arch_init_hypercalls(cpu))
kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
- /* The Guest tells us where we're not to deliver interrupts by putting
- * the range of addresses into "struct 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. */
+ /*
+ * 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 old page might be (read-only) in the Guest
- * pagetable. */
+ * pagetable.
+ */
guest_pagetable_clear_all(cpu);
}
/*:*/
-/*M:013 If a Guest reads from a page (so creates a mapping) that it has never
+/*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. :*/
+ * a similar scenario might one day bite us, so it's worth mentioning.
+ *
+ * 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
return;
}
- /* The Guest has initialized.
+ /*
+ * The Guest has initialized.
*
- * Look in the hypercall ring for the async hypercalls: */
+ * 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
+ /*
+ * 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. */
+ * the hypercall.
+ */
if (!cpu->pending_notify) {
do_hcall(cpu, cpu->hcall);
- /* Tricky point: we reset the hcall pointer to mark the
+ /*
+ * 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
* 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. */
+ * 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. */
+/*
+ * 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;
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