309 lines
9.2 KiB
C
309 lines
9.2 KiB
C
|
/*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.
|
||
|
|
:*/
|
||
|
|
|
||
|
|
/* Copyright (C) 2006 Rusty Russell IBM Corporation
|
||
|
|
|
||
|
|
This program is free software; you can redistribute it and/or modify
|
||
|
|
it under the terms of the GNU General Public License as published by
|
||
|
|
the Free Software Foundation; either version 2 of the License, or
|
||
|
|
(at your option) any later version.
|
||
|
|
|
||
|
|
This program is distributed in the hope that it will be useful,
|
||
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
GNU General Public License for more details.
|
||
|
|
|
||
|
|
You should have received a copy of the GNU General Public License
|
||
|
|
along with this program; if not, write to the Free Software
|
||
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
||
|
|
*/
|
||
|
|
#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 "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.
|
||
|
|
*/
|
||
|
|
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.
|
||
|
|
*/
|
||
|
|
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(cpu, "already have lguest_data");
|
||
|
|
break;
|
||
|
|
case LHCALL_SHUTDOWN: {
|
||
|
|
char msg[128];
|
||
|
|
/*
|
||
|
|
* 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);
|
||
|
|
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 (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.
|
||
|
|
*/
|
||
|
|
case LHCALL_NEW_PGTABLE:
|
||
|
|
guest_new_pagetable(cpu, args->arg1);
|
||
|
|
break;
|
||
|
|
case LHCALL_SET_STACK:
|
||
|
|
guest_set_stack(cpu, args->arg1, args->arg2, args->arg3);
|
||
|
|
break;
|
||
|
|
case LHCALL_SET_PTE:
|
||
|
|
#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_PGD:
|
||
|
|
guest_set_pgd(cpu->lg, args->arg1, args->arg2);
|
||
|
|
break;
|
||
|
|
#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(cpu, args->arg1);
|
||
|
|
break;
|
||
|
|
case LHCALL_TS:
|
||
|
|
/* This sets the TS flag, as we saw used in run_guest(). */
|
||
|
|
cpu->ts = args->arg1;
|
||
|
|
break;
|
||
|
|
case LHCALL_HALT:
|
||
|
|
/* Similarly, this sets the halted flag for run_guest(). */
|
||
|
|
cpu->halted = 1;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
/* It should be an architecture-specific hypercall. */
|
||
|
|
if (lguest_arch_do_hcall(cpu, args))
|
||
|
|
kill_guest(cpu, "Bad hypercall %li\n", args->arg0);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/*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 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, &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 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 = 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 (++cpu->next_hcall == LHCALL_RING_SIZE)
|
||
|
|
cpu->next_hcall = 0;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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(cpu, &args);
|
||
|
|
|
||
|
|
/* Mark the hypercall done. */
|
||
|
|
if (put_user(0xFF, &cpu->lg->lguest_data->hcall_status[n])) {
|
||
|
|
kill_guest(cpu, "Writing result for async hypercall");
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Stop doing hypercalls if they want to notify the Launcher:
|
||
|
|
* it needs to service this first.
|
||
|
|
*/
|
||
|
|
if (cpu->pending.trap)
|
||
|
|
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 lg_cpu *cpu)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
* 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 instruction address into "struct lguest_data".
|
||
|
|
*/
|
||
|
|
if (get_user(cpu->lg->noirq_iret, &cpu->lg->lguest_data->noirq_iret))
|
||
|
|
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
|
||
|
|
* 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.
|
||
|
|
*/
|
||
|
|
guest_pagetable_clear_all(cpu);
|
||
|
|
}
|
||
|
|
/*:*/
|
||
|
|
|
||
|
|
/*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.
|
||
|
|
*
|
||
|
|
* 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 lg_cpu *cpu)
|
||
|
|
{
|
||
|
|
/* 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.
|
||
|
|
*
|
||
|
|
* 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
|
||
|
|
* NOTIFY to the Launcher, we want to return now. Otherwise we do
|
||
|
|
* the hypercall.
|
||
|
|
*/
|
||
|
|
if (!cpu->pending.trap) {
|
||
|
|
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");
|
||
|
|
}
|