[PATCH v2 1/2] KVM: LAPIC: Return 0 when getting the tscdeadline timer if the lapic is hw disabled

[PATCH v2 1/2] KVM: LAPIC: Return 0 when getting the tscdeadline timer if the lapic is hw disabled

[Wanpeng Li]

From: Wanpeng Li <wanpengli@tencent.com>

Return 0 when getting the tscdeadline timer if the lapic is hw disabled.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v1 -> v2:
 * fix indentation

 arch/x86/kvm/lapic.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 5ccbee7..79599af 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2183,8 +2183,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
-	if (!lapic_in_kernel(vcpu) ||
-		!apic_lvtt_tscdeadline(apic))
+	if (!kvm_apic_present(vcpu) || !apic_lvtt_tscdeadline(apic))
 		return 0;
 
 	return apic->lapic_timer.tscdeadline;
-- 
2.7.4 

[PATCH v2 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

[Wanpeng Li]

From: Wanpeng Li <wanpengli@tencent.com>

Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
wrmsr MSR_IA32_TSCDEADLINE.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v1 -> v2:
 * fix indentation

 arch/x86/kvm/lapic.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 79599af..abaf48e 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2193,8 +2193,7 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
-	if (!kvm_apic_present(vcpu) || apic_lvtt_oneshot(apic) ||
-			apic_lvtt_period(apic))
+	if (!kvm_apic_present(vcpu) || !apic_lvtt_tscdeadline(apic))
 		return;
 
 	hrtimer_cancel(&apic->lapic_timer.timer);
-- 
2.7.4

Re: [PATCH v2 1/2] KVM: LAPIC: Return 0 when getting the tscdeadline timer if the lapic is hw disabled

[Sean Christopherson]

On Wed, Aug 12, 2020 at 02:30:37PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Return 0 when getting the tscdeadline timer if the lapic is hw disabled.

It'd be helpful to reference the SDM for the general behavior of the MSR.

  In other timer modes (LVT bit 18 = 0), the IA32_TSC_DEADLINE MSR reads
  zero and writes are ignored.

I'd also vote to squash the two patches together, they really are paired
changes to match the architectural behavior.

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

Re: [PATCH v2 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

[Sean Christopherson]

On Wed, Aug 12, 2020 at 02:30:38PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
> and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
> wrmsr MSR_IA32_TSCDEADLINE.
> 
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>

Gah, I take back my comment about squashing these, I assumed this was the
same fix but just in the write path.

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

> ---
> v1 -> v2:
>  * fix indentation
> 
>  arch/x86/kvm/lapic.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 79599af..abaf48e 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2193,8 +2193,7 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
>  {
>  	struct kvm_lapic *apic = vcpu->arch.apic;
>  
> -	if (!kvm_apic_present(vcpu) || apic_lvtt_oneshot(apic) ||
> -			apic_lvtt_period(apic))
> +	if (!kvm_apic_present(vcpu) || !apic_lvtt_tscdeadline(apic))
>  		return;
>  
>  	hrtimer_cancel(&apic->lapic_timer.timer);
> -- 
> 2.7.4
> 

Re: [PATCH v2 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

[Wanpeng Li]

ping :)
On Wed, 12 Aug 2020 at 14:30, Wanpeng Li <kernellwp@gmail.com> wrote:
>
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
> and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
> wrmsr MSR_IA32_TSCDEADLINE.
>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> v1 -> v2:
>  * fix indentation
>
>  arch/x86/kvm/lapic.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 79599af..abaf48e 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2193,8 +2193,7 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
>  {
>         struct kvm_lapic *apic = vcpu->arch.apic;
>
> -       if (!kvm_apic_present(vcpu) || apic_lvtt_oneshot(apic) ||
> -                       apic_lvtt_period(apic))
> +       if (!kvm_apic_present(vcpu) || !apic_lvtt_tscdeadline(apic))
>                 return;
>
>         hrtimer_cancel(&apic->lapic_timer.timer);
> --
> 2.7.4
>

Re: [PATCH v2 1/2] KVM: LAPIC: Return 0 when getting the tscdeadline timer if the lapic is hw disabled

[Sean Christopherson]

On Wed, Aug 12, 2020 at 02:30:37PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Return 0 when getting the tscdeadline timer if the lapic is hw disabled.
> 
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

Re: [PATCH v2 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

[Sean Christopherson]

On Wed, Aug 12, 2020 at 02:30:38PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
> and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
> wrmsr MSR_IA32_TSCDEADLINE.
> 
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>