linux-kernel - Re: [PATCH] x86:kvm:Fix error handling in the function kvm_lapic_sync_from

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Date:	Wed, 5 Aug 2015 16:54:58 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Nicholas Krause <xerofoify@...il.com>, gleb@...nel.org
Cc:	x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86:kvm:Fix error handling in the function
 kvm_lapic_sync_from_vapic



On 05/08/2015 16:44, Nicholas Krause wrote:
> This fixes error handling in the function kvm_lapic_sync_from_vapic
> by checking if the call to kvm_read_guest_cached has returned a
> error code to signal to its caller the call to this function has
> failed and due to this we must immediately return to the caller
> of kvm_lapic_sync_from_vapic to avoid incorrectly call apic_set_tpc
> if a error has occurred here.
> 
> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> ---
>  arch/x86/kvm/lapic.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 2a5ca97..9a3e342 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1900,8 +1900,9 @@ void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
>  	if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention))
>  		return;
>  
> -	kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data,
> -				sizeof(u32));
> +	if (kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data,
> +				  sizeof(u32)))
> +		return;
>  
>  	apic_set_tpr(vcpu->arch.apic, data & 0xff);
>  }
> 

Congratulations, this patch is good! :)

I'm applying it to kvm.git's queue branch.

Paolo
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