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authorPaolo Bonzini <pbonzini@redhat.com>2017-06-06 12:57:05 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-05 09:47:33 +0200
commite275005508a7a16e74c0e3dd49e31b7050b2763d (patch)
tree54a78820bf72b561274fa07d060b5666dd6f4cba
parent5170abd410a8eb619af4701ec5360832d97b29cf (diff)
KVM: VMX: avoid double list add with VT-d posted interrupts
commit 8b306e2f3c41939ea528e6174c88cfbfff893ce1 upstream. In some cases, for example involving hot-unplug of assigned devices, pi_post_block can forget to remove the vCPU from the blocked_vcpu_list. When this happens, the next call to pi_pre_block corrupts the list. Fix this in two ways. First, check vcpu->pre_pcpu in pi_pre_block and WARN instead of adding the element twice in the list. Second, always do the list removal in pi_post_block if vcpu->pre_pcpu is set (not -1). The new code keeps interrupts disabled for the whole duration of pi_pre_block/pi_post_block. This is not strictly necessary, but easier to follow. For the same reason, PI.ON is checked only after the cmpxchg, and to handle it we just call the post-block code. This removes duplication of the list removal code. Cc: Huangweidong <weidong.huang@huawei.com> Cc: Gonglei <arei.gonglei@huawei.com> Cc: wangxin <wangxinxin.wang@huawei.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Tested-by: Longpeng (Mike) <longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/vmx.c62
1 files changed, 25 insertions, 37 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 11dec3afcb8d..c1daec922ae4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11394,10 +11394,11 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct pi_desc old, new;
unsigned int dest;
- unsigned long flags;
do {
old.control = new.control = pi_desc->control;
+ WARN(old.nv != POSTED_INTR_WAKEUP_VECTOR,
+ "Wakeup handler not enabled while the VCPU is blocked\n");
dest = cpu_physical_id(vcpu->cpu);
@@ -11414,14 +11415,10 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
- if(vcpu->pre_pcpu != -1) {
- spin_lock_irqsave(
- &per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
+ if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {
+ spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_del(&vcpu->blocked_vcpu_list);
- spin_unlock_irqrestore(
- &per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
+ spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
vcpu->pre_pcpu = -1;
}
}
@@ -11441,7 +11438,6 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
*/
static int pi_pre_block(struct kvm_vcpu *vcpu)
{
- unsigned long flags;
unsigned int dest;
struct pi_desc old, new;
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
@@ -11451,34 +11447,20 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
!kvm_vcpu_apicv_active(vcpu))
return 0;
- vcpu->pre_pcpu = vcpu->cpu;
- spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
- list_add_tail(&vcpu->blocked_vcpu_list,
- &per_cpu(blocked_vcpu_on_cpu,
- vcpu->pre_pcpu));
- spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
+ WARN_ON(irqs_disabled());
+ local_irq_disable();
+ if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) {
+ vcpu->pre_pcpu = vcpu->cpu;
+ spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
+ list_add_tail(&vcpu->blocked_vcpu_list,
+ &per_cpu(blocked_vcpu_on_cpu,
+ vcpu->pre_pcpu));
+ spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
+ }
do {
old.control = new.control = pi_desc->control;
- /*
- * We should not block the vCPU if
- * an interrupt is posted for it.
- */
- if (pi_test_on(pi_desc) == 1) {
- spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
- list_del(&vcpu->blocked_vcpu_list);
- spin_unlock_irqrestore(
- &per_cpu(blocked_vcpu_on_cpu_lock,
- vcpu->pre_pcpu), flags);
- vcpu->pre_pcpu = -1;
-
- return 1;
- }
-
WARN((pi_desc->sn == 1),
"Warning: SN field of posted-interrupts "
"is set before blocking\n");
@@ -11503,7 +11485,12 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
- return 0;
+ /* We should not block the vCPU if an interrupt is posted for it. */
+ if (pi_test_on(pi_desc) == 1)
+ __pi_post_block(vcpu);
+
+ local_irq_enable();
+ return (vcpu->pre_pcpu == -1);
}
static int vmx_pre_block(struct kvm_vcpu *vcpu)
@@ -11519,12 +11506,13 @@ static int vmx_pre_block(struct kvm_vcpu *vcpu)
static void pi_post_block(struct kvm_vcpu *vcpu)
{
- if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (vcpu->pre_pcpu == -1)
return;
+ WARN_ON(irqs_disabled());
+ local_irq_disable();
__pi_post_block(vcpu);
+ local_irq_enable();
}
static void vmx_post_block(struct kvm_vcpu *vcpu)