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* [PATCH] KVM: x86: fix vcpu initialization with userspace lapic
@ 2018-03-01 14:24 Radim Krčmář
  2018-03-01 14:27 ` Dmitry Vyukov
  2018-03-01 14:37 ` Paolo Bonzini
  0 siblings, 2 replies; 3+ messages in thread
From: Radim Krčmář @ 2018-03-01 14:24 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: Paolo Bonzini, Dmitry Vyukov, stable

Moving the code around broke this rare configuration.
Use this opportunity to finally call lapic reset from vcpu reset.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Fixes: 0b2e9904c159 ("KVM: x86: move LAPIC initialization after VMCS creation")
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 arch/x86/kvm/lapic.c | 10 ++++------
 arch/x86/kvm/x86.c   |  3 ++-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index cc5fe7a50dde..391dda8d43b7 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2002,14 +2002,13 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 
 void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
-	struct kvm_lapic *apic;
+	struct kvm_lapic *apic = vcpu->arch.apic;
 	int i;
 
-	apic_debug("%s\n", __func__);
+	if (!apic)
+		return;
 
-	ASSERT(vcpu);
-	apic = vcpu->arch.apic;
-	ASSERT(apic != NULL);
+	apic_debug("%s\n", __func__);
 
 	/* Stop the timer in case it's a reset to an active apic */
 	hrtimer_cancel(&apic->lapic_timer.timer);
@@ -2568,7 +2567,6 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 
 	pe = xchg(&apic->pending_events, 0);
 	if (test_bit(KVM_APIC_INIT, &pe)) {
-		kvm_lapic_reset(vcpu, true);
 		kvm_vcpu_reset(vcpu, true);
 		if (kvm_vcpu_is_bsp(apic->vcpu))
 			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a3ed81031f1..3f96b51d0495 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8123,7 +8123,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 	kvm_vcpu_mtrr_init(vcpu);
 	vcpu_load(vcpu);
 	kvm_vcpu_reset(vcpu, false);
-	kvm_lapic_reset(vcpu, false);
 	kvm_mmu_setup(vcpu);
 	vcpu_put(vcpu);
 	return 0;
@@ -8166,6 +8165,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 
 void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
+	kvm_lapic_reset(vcpu, init_event);
+
 	vcpu->arch.hflags = 0;
 
 	vcpu->arch.smi_pending = 0;
-- 
2.15.1

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: fix vcpu initialization with userspace lapic
  2018-03-01 14:24 [PATCH] KVM: x86: fix vcpu initialization with userspace lapic Radim Krčmář
@ 2018-03-01 14:27 ` Dmitry Vyukov
  2018-03-01 14:37 ` Paolo Bonzini
  1 sibling, 0 replies; 3+ messages in thread
From: Dmitry Vyukov @ 2018-03-01 14:27 UTC (permalink / raw)
  To: Radim Krčmář; +Cc: LKML, KVM list, Paolo Bonzini, stable

On Thu, Mar 1, 2018 at 3:24 PM, Radim Krčmář <rkrcmar@redhat.com> wrote:
> Moving the code around broke this rare configuration.
> Use this opportunity to finally call lapic reset from vcpu reset.
>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>

This was reported by syzbot:
https://groups.google.com/d/msg/syzkaller-bugs/QrDXoM_mQRk/mT2cebykBQAJ

Please add the
Reported-by: syzbot+fb7a33a4b6c35007a72b@syzkaller.appspotmail.com
tag so that syzbot will know when it's fixed.

> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: 0b2e9904c159 ("KVM: x86: move LAPIC initialization after VMCS creation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  arch/x86/kvm/lapic.c | 10 ++++------
>  arch/x86/kvm/x86.c   |  3 ++-
>  2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index cc5fe7a50dde..391dda8d43b7 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2002,14 +2002,13 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
>
>  void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
>  {
> -       struct kvm_lapic *apic;
> +       struct kvm_lapic *apic = vcpu->arch.apic;
>         int i;
>
> -       apic_debug("%s\n", __func__);
> +       if (!apic)
> +               return;
>
> -       ASSERT(vcpu);
> -       apic = vcpu->arch.apic;
> -       ASSERT(apic != NULL);
> +       apic_debug("%s\n", __func__);
>
>         /* Stop the timer in case it's a reset to an active apic */
>         hrtimer_cancel(&apic->lapic_timer.timer);
> @@ -2568,7 +2567,6 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
>
>         pe = xchg(&apic->pending_events, 0);
>         if (test_bit(KVM_APIC_INIT, &pe)) {
> -               kvm_lapic_reset(vcpu, true);
>                 kvm_vcpu_reset(vcpu, true);
>                 if (kvm_vcpu_is_bsp(apic->vcpu))
>                         vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1a3ed81031f1..3f96b51d0495 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8123,7 +8123,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>         kvm_vcpu_mtrr_init(vcpu);
>         vcpu_load(vcpu);
>         kvm_vcpu_reset(vcpu, false);
> -       kvm_lapic_reset(vcpu, false);
>         kvm_mmu_setup(vcpu);
>         vcpu_put(vcpu);
>         return 0;
> @@ -8166,6 +8165,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
>
>  void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>  {
> +       kvm_lapic_reset(vcpu, init_event);
> +
>         vcpu->arch.hflags = 0;
>
>         vcpu->arch.smi_pending = 0;
> --
> 2.15.1
>

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: fix vcpu initialization with userspace lapic
  2018-03-01 14:24 [PATCH] KVM: x86: fix vcpu initialization with userspace lapic Radim Krčmář
  2018-03-01 14:27 ` Dmitry Vyukov
@ 2018-03-01 14:37 ` Paolo Bonzini
  1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2018-03-01 14:37 UTC (permalink / raw)
  To: Radim Krčmář, linux-kernel, kvm; +Cc: Dmitry Vyukov, stable

On 01/03/2018 15:24, Radim Krčmář wrote:
> Moving the code around broke this rare configuration.
> Use this opportunity to finally call lapic reset from vcpu reset.
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: 0b2e9904c159 ("KVM: x86: move LAPIC initialization after VMCS creation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  arch/x86/kvm/lapic.c | 10 ++++------
>  arch/x86/kvm/x86.c   |  3 ++-
>  2 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index cc5fe7a50dde..391dda8d43b7 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2002,14 +2002,13 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
>  
>  void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
>  {
> -	struct kvm_lapic *apic;
> +	struct kvm_lapic *apic = vcpu->arch.apic;
>  	int i;
>  
> -	apic_debug("%s\n", __func__);
> +	if (!apic)
> +		return;
>  
> -	ASSERT(vcpu);
> -	apic = vcpu->arch.apic;
> -	ASSERT(apic != NULL);
> +	apic_debug("%s\n", __func__);
>  
>  	/* Stop the timer in case it's a reset to an active apic */
>  	hrtimer_cancel(&apic->lapic_timer.timer);
> @@ -2568,7 +2567,6 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
>  
>  	pe = xchg(&apic->pending_events, 0);
>  	if (test_bit(KVM_APIC_INIT, &pe)) {
> -		kvm_lapic_reset(vcpu, true);
>  		kvm_vcpu_reset(vcpu, true);
>  		if (kvm_vcpu_is_bsp(apic->vcpu))
>  			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1a3ed81031f1..3f96b51d0495 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8123,7 +8123,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>  	kvm_vcpu_mtrr_init(vcpu);
>  	vcpu_load(vcpu);
>  	kvm_vcpu_reset(vcpu, false);
> -	kvm_lapic_reset(vcpu, false);
>  	kvm_mmu_setup(vcpu);
>  	vcpu_put(vcpu);
>  	return 0;
> @@ -8166,6 +8165,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
>  
>  void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>  {
> +	kvm_lapic_reset(vcpu, init_event);
> +
>  	vcpu->arch.hflags = 0;
>  
>  	vcpu->arch.smi_pending = 0;
> 

Much better indeed, thanks.

Paolo

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-03-01 14:37 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2018-03-01 14:24 [PATCH] KVM: x86: fix vcpu initialization with userspace lapic Radim Krčmář
2018-03-01 14:27 ` Dmitry Vyukov
2018-03-01 14:37 ` Paolo Bonzini

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