[PATCH qemu-server] cpu config: sev: add attestation parameters

[Loh Yu Chen <lohyuchen@gmail.com>]

The QEMU sev-guest object supports dh-cert-file and session-file parameters,
required for guest owner launch measurement attestation, but those are not
currently exposed.

These parameters are only applicable for type=std and type=es, as type=snp uses
a different attestation mechanism.

See https://www.qemu.org/docs/master/system/i386/amd-memory-encryption.html

Signed-off-by: Loh Yu Chen <lohyuchen@gmail.com>
---
 src/PVE/QemuServer/CPUConfig.pm | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/PVE/QemuServer/CPUConfig.pm b/src/PVE/QemuServer/CPUConfig.pm
index 32ec4954..8ae05b91 100644
--- a/src/PVE/QemuServer/CPUConfig.pm
+++ b/src/PVE/QemuServer/CPUConfig.pm
@@ -413,6 +413,20 @@ my $sev_fmt = {
         default => 0,
         optional => 1,
     },
+    "dh-cert-file" => {
+        description => "Path to guest owner Diffie-Hellman certificate file for SEV(-ES) attestation"
+            . " (Ignored for SEV-SNP)",
+        type => 'string',
+        format_description => 'filepath',
+        optional => 1,
+    },
+    "session-file" => {
+        description => "Path to the session blob file generated by the guest owner for SEV(-ES) attestation"
+            . " (Ignored for SEV-SNP)",
+        type => 'string',
+        format_description => 'filepath',
+        optional => 1,
+    },
 };
 PVE::JSONSchema::register_format('pve-qemu-sev-fmt', $sev_fmt);
 
@@ -1173,6 +1187,20 @@ sub get_amd_sev_object {
         $policy |= 1 << 2 if $amd_sev_conf->{type} eq 'es';
         # disable migration with bit 3 nosend to prevent amd-sev-migration-attack
         $policy |= 1 << 3;
+
+        if (defined($amd_sev_conf->{'dh-cert-file'}) xor defined($amd_sev_conf->{'session-file'})) {
+            die "dh-cert-file and session-file must be specified together.\n";
+        }
+        if (defined($amd_sev_conf->{'dh-cert-file'})) {
+            if (!-f $amd_sev_conf->{'dh-cert-file'}) {
+                die "dh-cert-file '$amd_sev_conf->{'dh-cert-file'}' does not exist.\n";
+            }
+            if (!-f $amd_sev_conf->{'session-file'}) {
+                die "session-file '$amd_sev_conf->{'session-file'}' does not exist.\n";
+            }
+            $sev_mem_object .= ',dh-cert-file=' . $amd_sev_conf->{'dh-cert-file'};
+            $sev_mem_object .= ',session-file=' . $amd_sev_conf->{'session-file'};
+        }
     } elsif ($amd_sev_conf->{type} eq 'snp') {
         $sev_mem_object .= 'sev-snp-guest,id=sev0';
         $sev_mem_object .= ',cbitpos=' . $sev_hw_caps->{cbitpos};
-- 
2.53.0.windows.1