2022-03-08 19:49:02

by Suthikulpanit, Suravee

Subject: [RFCv2 PATCH 11/12] KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu

Originalliy, this WARN_ON is designed to detect when calling
avic_vcpu_load() on an already running vcpu in AVIC mode (i.e. the AVIC
is_running bit is set).

However, for x2AVIC, the vCPU can switch from xAPIC to x2APIC mode while in
running state, in which the avic_vcpu_load() will be called from
svm_refresh_apicv_exec_ctrl().

Therefore, remove this warning since it is no longer appropriate.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
---
arch/x86/kvm/svm/avic.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index b8d6bf6b6ed5..015888aad8fc 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -1038,7 +1038,6 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
return;

entry = READ_ONCE(*(svm->avic_physical_id_cache));
- WARN_ON(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK);

entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);
--
2.25.1

2022-03-25 02:45:51

by Maxim Levitsky

Subject: Re: [RFCv2 PATCH 11/12] KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu

On Tue, 2022-03-08 at 10:39 -0600, Suravee Suthikulpanit wrote:
> Originalliy, this WARN_ON is designed to detect when calling
> avic_vcpu_load() on an already running vcpu in AVIC mode (i.e. the AVIC
> is_running bit is set).
>
> However, for x2AVIC, the vCPU can switch from xAPIC to x2APIC mode while in
> running state, in which the avic_vcpu_load() will be called from
> svm_refresh_apicv_exec_ctrl().
>
> Therefore, remove this warning since it is no longer appropriate.
>
> Signed-off-by: Suravee Suthikulpanit <[email protected]>
> ---
> arch/x86/kvm/svm/avic.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index b8d6bf6b6ed5..015888aad8fc 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -1038,7 +1038,6 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> return;
>
> entry = READ_ONCE(*(svm->avic_physical_id_cache));
> - WARN_ON(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK);
>
> entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
> entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);


Reviewed-by: Maxim Levitsky <[email protected]>

Best regards,
Maxim Levitsky