aboutsummaryrefslogtreecommitdiff
path: root/virt
diff options
context:
space:
mode:
authorMarcelo Tosatti <mtosatti@redhat.com>2009-05-07 17:55:13 -0300
committerAvi Kivity <avi@redhat.com>2009-06-10 11:48:53 +0300
commit547de29e5b1662deb05b5f90917902dc0e9ac182 (patch)
treec8c8d913729f4577251d3bceb9fe52b676f7a5a8 /virt
parent32f8840064d88cc3f6e85203aec7b6b57bebcb97 (diff)
downloadlinux-linaro-stable-547de29e5b1662deb05b5f90917902dc0e9ac182.tar.gz
KVM: protect assigned dev workqueue, int handler and irq acker
kvm_assigned_dev_ack_irq is vulnerable to a race condition with the interrupt handler function. It does: if (dev->host_irq_disabled) { enable_irq(dev->host_irq); dev->host_irq_disabled = false; } If an interrupt triggers before the host->dev_irq_disabled assignment, it will disable the interrupt and set dev->host_irq_disabled to true. On return to kvm_assigned_dev_ack_irq, dev->host_irq_disabled is set to false, and the next kvm_assigned_dev_ack_irq call will fail to reenable it. Other than that, having the interrupt handler and work handlers run in parallel sounds like asking for trouble (could not spot any obvious problem, but better not have to, its fragile). CC: sheng.yang@intel.com Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 29c0afb064da..687d113a3e5e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -42,6 +42,7 @@
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/bitops.h>
+#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/io.h>
@@ -130,6 +131,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
* finer-grained lock, update this
*/
mutex_lock(&kvm->lock);
+ spin_lock_irq(&assigned_dev->assigned_dev_lock);
if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
struct kvm_guest_msix_entry *guest_entries =
assigned_dev->guest_msix_entries;
@@ -156,18 +158,21 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
}
}
+ spin_unlock_irq(&assigned_dev->assigned_dev_lock);
mutex_unlock(&assigned_dev->kvm->lock);
}
static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
{
+ unsigned long flags;
struct kvm_assigned_dev_kernel *assigned_dev =
(struct kvm_assigned_dev_kernel *) dev_id;
+ spin_lock_irqsave(&assigned_dev->assigned_dev_lock, flags);
if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
int index = find_index_from_host_irq(assigned_dev, irq);
if (index < 0)
- return IRQ_HANDLED;
+ goto out;
assigned_dev->guest_msix_entries[index].flags |=
KVM_ASSIGNED_MSIX_PENDING;
}
@@ -177,6 +182,8 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
disable_irq_nosync(irq);
assigned_dev->host_irq_disabled = true;
+out:
+ spin_unlock_irqrestore(&assigned_dev->assigned_dev_lock, flags);
return IRQ_HANDLED;
}
@@ -184,6 +191,7 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
{
struct kvm_assigned_dev_kernel *dev;
+ unsigned long flags;
if (kian->gsi == -1)
return;
@@ -196,10 +204,12 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
/* The guest irq may be shared so this ack may be
* from another device.
*/
+ spin_lock_irqsave(&dev->assigned_dev_lock, flags);
if (dev->host_irq_disabled) {
enable_irq(dev->host_irq);
dev->host_irq_disabled = false;
}
+ spin_unlock_irqrestore(&dev->assigned_dev_lock, flags);
}
static void deassign_guest_irq(struct kvm *kvm,
@@ -615,6 +625,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
match->host_devfn = assigned_dev->devfn;
match->flags = assigned_dev->flags;
match->dev = dev;
+ spin_lock_init(&match->assigned_dev_lock);
match->irq_source_id = -1;
match->kvm = kvm;
match->ack_notifier.irq_acked = kvm_assigned_dev_ack_irq;