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Subject: Re: [PATCH] KVM: x86: document behavior of measurement ioctls with
 len==0
To:     Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
References: <20210420093411.1498840-1-pbonzini@redhat.com>
From:   Brijesh Singh <brijesh.singh@amd.com>
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On 4/20/21 4:34 AM, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>


Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>

Thanks

> ---
>  Documentation/virt/kvm/amd-memory-encryption.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index 469a6308765b..34ce2d1fcb89 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -148,6 +148,9 @@ measurement. Since the guest owner knows the initial contents of the guest at
>  boot, the measurement can be verified by comparing it to what the guest owner
>  expects.
>  
> +If len is zero on entry, the measurement blob length is written to len and
> +uaddr is unused.
> +
>  Parameters (in): struct  kvm_sev_launch_measure
>  
>  Returns: 0 on success, -negative on error
> @@ -271,6 +274,9 @@ report containing the SHA-256 digest of the guest memory and VMSA passed through
>  commands and signed with the PEK. The digest returned by the command should match the digest
>  used by the guest owner with the KVM_SEV_LAUNCH_MEASURE.
>  
> +If len is zero on entry, the measurement blob length is written to len and
> +uaddr is unused.
> +
>  Parameters (in): struct kvm_sev_attestation
>  
>  Returns: 0 on success, -negative on error