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Message-ID: <9875fd216464cabcc14cbaa2df374b2b3dc937bb.camel@redhat.com>
Subject: Re: [RFCv2 PATCH 11/12] KVM: SVM: Do not throw warning when calling
 avic_vcpu_load on a running vcpu
From:   Maxim Levitsky <mlevitsk@redhat.com>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     pbonzini@redhat.com, seanjc@google.com, joro@8bytes.org,
        jon.grimm@amd.com, wei.huang2@amd.com, terry.bowman@amd.com
Date:   Thu, 24 Mar 2022 17:42:00 +0200
In-Reply-To: <20220308163926.563994-12-suravee.suthikulpanit@amd.com>
References: <20220308163926.563994-1-suravee.suthikulpanit@amd.com>
         <20220308163926.563994-12-suravee.suthikulpanit@amd.com>
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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 <suravee.suthikulpanit@amd.com>
> ---
>  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 <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky