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From 9adf5e57df32df464e7465b1df72c993d0ed4ed4 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 31 Jul 2020 18:08:35 -0400
Subject: [PATCH 3/4] target/i386: sev: fail query-sev-capabilities if QEMU
 cannot use SEV
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20200731180835.86786-3-pbonzini@redhat.com>
Patchwork-id: 98124
O-Subject: [RHEL-8.3.0 qemu-kvm PATCH 2/2] target/i386: sev: fail query-sev-capabilities if QEMU cannot use SEV
Bugzilla: 1689341
RH-Acked-by: Danilo de Paula <ddepaula@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

In some cases, such as if the kvm-amd "sev" module parameter is set
to 0, SEV will be unavailable but query-sev-capabilities will still
return all the information.  This tricks libvirt into erroneously
reporting that SEV is available.  Check the actual usability of the
feature and return the appropriate error if QEMU cannot use KVM
or KVM cannot use SEV.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
cherry picked from commit 1b38750c40281dd0d068f8536b2ea95d7b9bd585
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 target/i386/sev.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 054f2d846a..a47f0d3880 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -504,6 +504,15 @@ sev_get_capabilities(Error **errp)
     uint32_t ebx;
     int fd;
 
+    if (!kvm_enabled()) {
+        error_setg(errp, "KVM not enabled");
+        return NULL;
+    }
+    if (kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_OP, NULL) < 0) {
+        error_setg(errp, "SEV is not enabled in KVM");
+        return NULL;
+    }
+
     fd = open(DEFAULT_SEV_DEVICE, O_RDWR);
     if (fd < 0) {
         error_setg_errno(errp, errno, "Failed to open %s",
-- 
2.27.0