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linux/virt/kvm/ioapic.c
Mark McLoughlin 35baff256d KVM: IOAPIC: Fix level-triggered irq injection hang 
The "remote_irr" variable is used to indicate an interrupt
which has been received by the LAPIC, but not acked.

In our EOI handler, we unset remote_irr and re-inject the
interrupt if the interrupt line is still asserted.

However, we do not set remote_irr here, leading to a
situation where if kvm_ioapic_set_irq() is called, then we go
ahead and call ioapic_service(). This means that IRR is
re-asserted even though the interrupt is currently in service
(i.e. LAPIC IRR is cleared and ISR/TMR set)

The issue with this is that when the currently executing
interrupt handler finishes and writes LAPIC EOI, then TMR is
unset and EOI sent to the IOAPIC. Since IRR is now asserted,
but TMR is not, then when the second interrupt is handled,
no EOI is sent and if there is any pending interrupt, it is
not re-injected.

This fixes a hang only seen while running mke2fs -j on an
8Gb virtio disk backed by a fully sparse raw file, with
aliguori "avoid fragmented virtio-blk transfers by copying"
changes.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-06 11:05:35 +03:00

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/*
* Copyright (C) 2001 MandrakeSoft S.A.
*
* MandrakeSoft S.A.
* 43, rue d'Aboukir
* 75002 Paris - France
* http://www.linux-mandrake.com/
* http://www.mandrakesoft.com/
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Yunhong Jiang <yunhong.jiang@intel.com>
* Yaozu (Eddie) Dong <eddie.dong@intel.com>
* Based on Xen 3.1 code.
*/
#include <linux/kvm_host.h>
#include <linux/kvm.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/smp.h>
#include <linux/hrtimer.h>
#include <linux/io.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/current.h>
#include "ioapic.h"
#include "lapic.h"
#if 0
#define ioapic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg)
#else
#define ioapic_debug(fmt, arg...)
#endif
static int ioapic_deliver(struct kvm_ioapic *vioapic, int irq);
static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
unsigned long addr,
unsigned long length)
{
unsigned long result = 0;
switch (ioapic->ioregsel) {
case IOAPIC_REG_VERSION:
result = ((((IOAPIC_NUM_PINS - 1) & 0xff) << 16)
| (IOAPIC_VERSION_ID & 0xff));
break;
case IOAPIC_REG_APIC_ID:
case IOAPIC_REG_ARB_ID:
result = ((ioapic->id & 0xf) << 24);
break;
default:
{
u32 redir_index = (ioapic->ioregsel - 0x10) >> 1;
u64 redir_content;
ASSERT(redir_index < IOAPIC_NUM_PINS);
redir_content = ioapic->redirtbl[redir_index].bits;
result = (ioapic->ioregsel & 0x1) ?
(redir_content >> 32) & 0xffffffff :
redir_content & 0xffffffff;
break;
}
}
return result;
}
static void ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx)
{
union ioapic_redir_entry *pent;
pent = &ioapic->redirtbl[idx];
if (!pent->fields.mask) {
int injected = ioapic_deliver(ioapic, idx);
if (injected && pent->fields.trig_mode == IOAPIC_LEVEL_TRIG)
pent->fields.remote_irr = 1;
}
if (!pent->fields.trig_mode)
ioapic->irr &= ~(1 << idx);
}
static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
{
unsigned index;
switch (ioapic->ioregsel) {
case IOAPIC_REG_VERSION:
/* Writes are ignored. */
break;
case IOAPIC_REG_APIC_ID:
ioapic->id = (val >> 24) & 0xf;
break;
case IOAPIC_REG_ARB_ID:
break;
default:
index = (ioapic->ioregsel - 0x10) >> 1;
ioapic_debug("change redir index %x val %x\n", index, val);
if (index >= IOAPIC_NUM_PINS)
return;
if (ioapic->ioregsel & 1) {
ioapic->redirtbl[index].bits &= 0xffffffff;
ioapic->redirtbl[index].bits |= (u64) val << 32;
} else {
ioapic->redirtbl[index].bits &= ~0xffffffffULL;
ioapic->redirtbl[index].bits |= (u32) val;
ioapic->redirtbl[index].fields.remote_irr = 0;
}
if (ioapic->irr & (1 << index))
ioapic_service(ioapic, index);
break;
}
}
static int ioapic_inj_irq(struct kvm_ioapic *ioapic,
struct kvm_vcpu *vcpu,
u8 vector, u8 trig_mode, u8 delivery_mode)
{
ioapic_debug("irq %d trig %d deliv %d\n", vector, trig_mode,
delivery_mode);
ASSERT((delivery_mode == IOAPIC_FIXED) ||
(delivery_mode == IOAPIC_LOWEST_PRIORITY));
return kvm_apic_set_irq(vcpu, vector, trig_mode);
}
static u32 ioapic_get_delivery_bitmask(struct kvm_ioapic *ioapic, u8 dest,
u8 dest_mode)
{
u32 mask = 0;
int i;
struct kvm *kvm = ioapic->kvm;
struct kvm_vcpu *vcpu;
ioapic_debug("dest %d dest_mode %d\n", dest, dest_mode);
if (dest_mode == 0) { /* Physical mode. */
if (dest == 0xFF) { /* Broadcast. */
for (i = 0; i < KVM_MAX_VCPUS; ++i)
if (kvm->vcpus[i] && kvm->vcpus[i]->arch.apic)
mask |= 1 << i;
return mask;
}
for (i = 0; i < KVM_MAX_VCPUS; ++i) {
vcpu = kvm->vcpus[i];
if (!vcpu)
continue;
if (kvm_apic_match_physical_addr(vcpu->arch.apic, dest)) {
if (vcpu->arch.apic)
mask = 1 << i;
break;
}
}
} else if (dest != 0) /* Logical mode, MDA non-zero. */
for (i = 0; i < KVM_MAX_VCPUS; ++i) {
vcpu = kvm->vcpus[i];
if (!vcpu)
continue;
if (vcpu->arch.apic &&
kvm_apic_match_logical_addr(vcpu->arch.apic, dest))
mask |= 1 << vcpu->vcpu_id;
}
ioapic_debug("mask %x\n", mask);
return mask;
}
static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
{
u8 dest = ioapic->redirtbl[irq].fields.dest_id;
u8 dest_mode = ioapic->redirtbl[irq].fields.dest_mode;
u8 delivery_mode = ioapic->redirtbl[irq].fields.delivery_mode;
u8 vector = ioapic->redirtbl[irq].fields.vector;
u8 trig_mode = ioapic->redirtbl[irq].fields.trig_mode;
u32 deliver_bitmask;
struct kvm_vcpu *vcpu;
int vcpu_id, r = 0;
ioapic_debug("dest=%x dest_mode=%x delivery_mode=%x "
"vector=%x trig_mode=%x\n",
dest, dest_mode, delivery_mode, vector, trig_mode);
deliver_bitmask = ioapic_get_delivery_bitmask(ioapic, dest, dest_mode);
if (!deliver_bitmask) {
ioapic_debug("no target on destination\n");
return 0;
}
switch (delivery_mode) {
case IOAPIC_LOWEST_PRIORITY:
vcpu = kvm_get_lowest_prio_vcpu(ioapic->kvm, vector,
deliver_bitmask);
#ifdef CONFIG_X86
if (irq == 0)
vcpu = ioapic->kvm->vcpus[0];
#endif
if (vcpu != NULL)
r = ioapic_inj_irq(ioapic, vcpu, vector,
trig_mode, delivery_mode);
else
ioapic_debug("null lowest prio vcpu: "
"mask=%x vector=%x delivery_mode=%x\n",
deliver_bitmask, vector, IOAPIC_LOWEST_PRIORITY);
break;
case IOAPIC_FIXED:
#ifdef CONFIG_X86
if (irq == 0)
deliver_bitmask = 1;
#endif
for (vcpu_id = 0; deliver_bitmask != 0; vcpu_id++) {
if (!(deliver_bitmask & (1 << vcpu_id)))
continue;
deliver_bitmask &= ~(1 << vcpu_id);
vcpu = ioapic->kvm->vcpus[vcpu_id];
if (vcpu) {
r = ioapic_inj_irq(ioapic, vcpu, vector,
trig_mode, delivery_mode);
}
}
break;
/* TODO: NMI */
default:
printk(KERN_WARNING "Unsupported delivery mode %d\n",
delivery_mode);
break;
}
return r;
}
void kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
{
u32 old_irr = ioapic->irr;
u32 mask = 1 << irq;
union ioapic_redir_entry entry;
if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
entry = ioapic->redirtbl[irq];
level ^= entry.fields.polarity;
if (!level)
ioapic->irr &= ~mask;
else {
ioapic->irr |= mask;
if ((!entry.fields.trig_mode && old_irr != ioapic->irr)
|| !entry.fields.remote_irr)
ioapic_service(ioapic, irq);
}
}
}
static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int gsi)
{
union ioapic_redir_entry *ent;
ent = &ioapic->redirtbl[gsi];
ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
ent->fields.remote_irr = 0;
if (!ent->fields.mask && (ioapic->irr & (1 << gsi)))
ioapic_service(ioapic, gsi);
}
void kvm_ioapic_update_eoi(struct kvm *kvm, int vector)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++)
if (ioapic->redirtbl[i].fields.vector == vector)
__kvm_ioapic_update_eoi(ioapic, i);
}
static int ioapic_in_range(struct kvm_io_device *this, gpa_t addr)
{
struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private;
return ((addr >= ioapic->base_address &&
(addr < ioapic->base_address + IOAPIC_MEM_LENGTH)));
}
static void ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
void *val)
{
struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private;
u32 result;
ioapic_debug("addr %lx\n", (unsigned long)addr);
ASSERT(!(addr & 0xf)); /* check alignment */
addr &= 0xff;
switch (addr) {
case IOAPIC_REG_SELECT:
result = ioapic->ioregsel;
break;
case IOAPIC_REG_WINDOW:
result = ioapic_read_indirect(ioapic, addr, len);
break;
default:
result = 0;
break;
}
switch (len) {
case 8:
*(u64 *) val = result;
break;
case 1:
case 2:
case 4:
memcpy(val, (char *)&result, len);
break;
default:
printk(KERN_WARNING "ioapic: wrong length %d\n", len);
}
}
static void ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
const void *val)
{
struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private;
u32 data;
ioapic_debug("ioapic_mmio_write addr=%p len=%d val=%p\n",
(void*)addr, len, val);
ASSERT(!(addr & 0xf)); /* check alignment */
if (len == 4 || len == 8)
data = *(u32 *) val;
else {
printk(KERN_WARNING "ioapic: Unsupported size %d\n", len);
return;
}
addr &= 0xff;
switch (addr) {
case IOAPIC_REG_SELECT:
ioapic->ioregsel = data;
break;
case IOAPIC_REG_WINDOW:
ioapic_write_indirect(ioapic, data);
break;
#ifdef CONFIG_IA64
case IOAPIC_REG_EOI:
kvm_ioapic_update_eoi(ioapic->kvm, data);
break;
#endif
default:
break;
}
}
void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
{
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++)
ioapic->redirtbl[i].fields.mask = 1;
ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
ioapic->ioregsel = 0;
ioapic->irr = 0;
ioapic->id = 0;
}
int kvm_ioapic_init(struct kvm *kvm)
{
struct kvm_ioapic *ioapic;
ioapic = kzalloc(sizeof(struct kvm_ioapic), GFP_KERNEL);
if (!ioapic)
return -ENOMEM;
kvm->arch.vioapic = ioapic;
kvm_ioapic_reset(ioapic);
ioapic->dev.read = ioapic_mmio_read;
ioapic->dev.write = ioapic_mmio_write;
ioapic->dev.in_range = ioapic_in_range;
ioapic->dev.private = ioapic;
ioapic->kvm = kvm;
kvm_io_bus_register_dev(&kvm->mmio_bus, &ioapic->dev);
return 0;
}
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