linux-kernel - Re: [PATCH 1/8] KVM: SEV-ES: fix length of string I/O

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Date:   Fri, 22 Oct 2021 02:10:08 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     fwilhelm@...gle.com, seanjc@...gle.com, oupton@...gle.com,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/8] KVM: SEV-ES: fix length of string I/O

On Wed, 2021-10-13 at 12:56 -0400, Paolo Bonzini wrote:
> The size of the data in the scratch buffer is not divided by the size of
> each port I/O operation, so vcpu->arch.pio.count ends up being larger
> than it should be by a factor of size.
> 
> Cc: stable@...r.kernel.org
> Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest")
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/svm/sev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index c36b5fe4c27c..e672493b5d8d 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2583,7 +2583,7 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in)
>  		return -EINVAL;
>  
>  	return kvm_sev_es_string_io(&svm->vcpu, size, port,
> -				    svm->ghcb_sa, svm->ghcb_sa_len, in);
> +				    svm->ghcb_sa, svm->ghcb_sa_len / size, in);
>  }
>  
>  void sev_es_init_vmcb(struct vcpu_svm *svm)

This ends in kvm_sev_es_ins/outs and both indeed expect count of operations which they pass to emulator_pio_{out|in}_emulated

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky