linux-kernel - Re: [PATCH v2] svm/avic: Fix invalidate logical APIC id entry

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Message-ID: <5425ef2b-75bc-d500-d39a-3d73e217a13c@redhat.com>
Date:   Tue, 9 Apr 2019 18:39:53 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Cc:     "joro@...tes.org" <joro@...tes.org>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>
Subject: Re: [PATCH v2] svm/avic: Fix invalidate logical APIC id entry

On 26/03/19 04:57, Suthikulpanit, Suravee wrote:
> Only clear the valid bit when invalidate logical APIC id entry.
> The current logic clear the valid bit, but also set the rest of
> the bits (including reserved bits) to 1.
> 
> Fixes: 98d90582be2e ('svm: Fix AVIC DFR and LDR handling')
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  arch/x86/kvm/svm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 7a4ce1a22ca0..8a123bd0f591 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -270,6 +270,7 @@ struct amd_svm_iommu_ir {
>  };
>  
>  #define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK	(0xFF)
> +#define AVIC_LOGICAL_ID_ENTRY_VALID_BIT			31
>  #define AVIC_LOGICAL_ID_ENTRY_VALID_MASK		(1 << 31)
>  
>  #define AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK	(0xFFULL)
> @@ -4640,7 +4641,7 @@ static void avic_invalidate_logical_id_entry(struct kvm_vcpu *vcpu)
>  	u32 *entry = avic_get_logical_id_entry(vcpu, svm->ldr_reg, flat);
>  
>  	if (entry)
> -		WRITE_ONCE(*entry, (u32) ~AVIC_LOGICAL_ID_ENTRY_VALID_MASK);
> +		clear_bit(AVIC_LOGICAL_ID_ENTRY_VALID_BIT, (unsigned long *)entry);
>  }
>  
>  static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
> 

Queued both this and the revert, thanks.

Paolo