Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Paolo Bonzini <pbonzini@redhat.com>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH] KVM: x86: document behavior of measurement ioctls with len==0
Date:   Tue, 20 Apr 2021 05:34:11 -0400
Message-Id: <20210420093411.1498840-1-pbonzini@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 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
-- 
2.26.2