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/*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 <asm/page.h>
#include <asm/pgtable.h>
#include <irq_vectors.h>
#include "lg.h"
static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
{
switch (regs->eax) {
case LHCALL_FLUSH_ASYNC:
break;
case LHCALL_LGUEST_INIT:
kill_guest(lg, "already have lguest_data");
break;
case LHCALL_CRASH: {
char msg[128];
lgread(lg, msg, regs->edx, sizeof(msg));
msg[sizeof(msg)-1] = '\0';
kill_guest(lg, "CRASH: %s", msg);
break;
}
case LHCALL_FLUSH_TLB:
if (regs->edx)
guest_pagetable_clear_all(lg);
else
guest_pagetable_flush_user(lg);
break;
case LHCALL_GET_WALLCLOCK: {
struct timespec ts;
ktime_get_real_ts(&ts);
regs->eax = ts.tv_sec;
break;
}
case LHCALL_BIND_DMA:
regs->eax = bind_dma(lg, regs->edx, regs->ebx,
regs->ecx >> 8, regs->ecx & 0xFF);
break;
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;
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(lg, regs->edx);
break;
case LHCALL_SET_STACK:
guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
break;
case LHCALL_SET_PTE:
guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
break;
case LHCALL_SET_PMD:
guest_set_pmd(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_TLS:
guest_load_tls(lg, regs->edx);
break;
case LHCALL_SET_CLOCKEVENT:
guest_set_clockevent(lg, regs->edx);
break;
case LHCALL_TS:
lg->ts = regs->edx;
break;
case LHCALL_HALT:
lg->halted = 1;
break;
default:
kill_guest(lg, "Bad hypercall %li\n", regs->eax);
}
}
/* We always do queued calls before actual hypercall. */
static void do_async_hcalls(struct lguest *lg)
{
unsigned int i;
u8 st[LHCALL_RING_SIZE];
if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
return;
for (i = 0; i < ARRAY_SIZE(st); i++) {
struct lguest_regs regs;
unsigned int n = lg->next_hcall;
if (st[n] == 0xFF)
break;
if (++lg->next_hcall == LHCALL_RING_SIZE)
lg->next_hcall = 0;
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");
break;
}
do_hcall(lg, ®s);
if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
kill_guest(lg, "Writing result for async hypercall");
break;
}
if (lg->dma_is_pending)
break;
}
}
static void initialize(struct lguest *lg)
{
u32 tsc_speed;
if (lg->regs->eax != LHCALL_LGUEST_INIT) {
kill_guest(lg, "hypercall %li before LGUEST_INIT",
lg->regs->eax);
return;
}
/* We only tell the guest to use the TSC if it's reliable. */
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
tsc_speed = tsc_khz;
else
tsc_speed = 0;
lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
/* We check here so we can simply copy_to_user/from_user */
if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
kill_guest(lg, "bad guest page %p", lg->lguest_data);
return;
}
if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
/* We reserve the top pgd entry. */
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
|| put_user(tsc_speed, &lg->lguest_data->tsc_khz)
|| put_user(lg->guestid, &lg->lguest_data->guestid))
kill_guest(lg, "bad guest page %p", lg->lguest_data);
/* 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);
}
/* Even if we go out to userspace and come back, we don't want to do
* the hypercall again. */
static void clear_hcall(struct lguest *lg)
{
lg->regs->trapnum = 255;
}
void do_hypercalls(struct lguest *lg)
{
if (unlikely(!lg->lguest_data)) {
if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
initialize(lg);
clear_hcall(lg);
}
return;
}
do_async_hcalls(lg);
if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
do_hcall(lg, lg->regs);
clear_hcall(lg);
}
}
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