File 764491c9-qemu-fix-probing-sev-support.patch of Package libvirt.22293

commit 764491c9dddf063292adf1433769ccccb1a50db6
Author: Erik Skultety <eskultet@redhat.com>
Date:   Tue Aug 14 15:54:46 2018 +0200

    qemu: Fix probing of AMD SEV support
    
    So the procedure to detect SEV support works like this:
    1) we detect that sev-guest is among the QOM types and set the cap flag
    2) we probe the monitor for SEV support
        - this is tricky, because QEMU with compiled SEV support will always
        report -object sev-guest and query-sev-capabilities command, that
        however doesn't mean SEV is supported
    3) depending on what the monitor returned, we either keep or clear the
    capability flag for SEV
    
    Commit a349c6c21c6 added an explicit check for "GenericError" in the
    monitor reply to prevent libvirtd to spam logs about missing
    'query-sev-capabilities' command. At the same time though, it returned
    success in this case which means that we didn't clear the capability
    flag afterwards and happily formatted SEV into qemuCaps. Therefore,
    adjust all the relevant callers to handle -1 on errors, 0 on SEV being
    unsupported and 1 on SEV being supported.
    
    Signed-off-by: Erik Skultety <eskultet@redhat.com>
    Acked-by: Peter Krempa <pkrempa@redhat.com>

Index: libvirt-4.0.0/src/qemu/qemu_capabilities.c
===================================================================
--- libvirt-4.0.0.orig/src/qemu/qemu_capabilities.c
+++ libvirt-4.0.0/src/qemu/qemu_capabilities.c
@@ -3322,18 +3322,20 @@ virQEMUCapsProbeQMPGICCapabilities(virQE
 }
 
 
+/* Returns -1 on error, 0 if SEV is not supported, 1 if SEV is supported */
 static int
 virQEMUCapsProbeQMPSEVCapabilities(virQEMUCapsPtr qemuCaps,
                                    qemuMonitorPtr mon)
 {
+    int rc = -1;
     virSEVCapability *caps = NULL;
 
-    if (qemuMonitorGetSEVCapabilities(mon, &caps) < 0)
-        return -1;
+    if ((rc = qemuMonitorGetSEVCapabilities(mon, &caps)) <= 0)
+        return rc;
 
     virSEVCapabilitiesFree(qemuCaps->sevCapabilities);
     qemuCaps->sevCapabilities = caps;
-    return 0;
+    return rc;
 }
 
 
@@ -4949,7 +4951,12 @@ virQEMUCapsInitQMPMonitor(virQEMUCapsPtr
 
     /* Probe for SEV capabilities */
     if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV_GUEST)) {
-        if (virQEMUCapsProbeQMPSEVCapabilities(qemuCaps, mon) < 0)
+        int rc = virQEMUCapsProbeQMPSEVCapabilities(qemuCaps, mon);
+
+        if (rc < 0)
+            goto cleanup;
+
+        if (rc == 0)
             virQEMUCapsClear(qemuCaps, QEMU_CAPS_SEV_GUEST);
     }
 
Index: libvirt-4.0.0/src/qemu/qemu_monitor_json.c
===================================================================
--- libvirt-4.0.0.orig/src/qemu/qemu_monitor_json.c
+++ libvirt-4.0.0/src/qemu/qemu_monitor_json.c
@@ -6263,6 +6263,20 @@ qemuMonitorJSONGetGICCapabilities(qemuMo
 }
 
 
+/**
+ * qemuMonitorJSONGetSEVCapabilities:
+ * @mon: qemu monitor object
+ * @capabilities: pointer to pointer to a SEV capability structure to be filled
+ *
+ * This function queries and fills in AMD's SEV platform-specific data.
+ * Note that from QEMU's POV both -object sev-guest and query-sev-capabilities
+ * can be present even if SEV is not available, which basically leaves us with
+ * checking for JSON "GenericError" in order to differentiate between
+ * compiled-in support and actual SEV support on the platform.
+ *
+ * Returns -1 on error, 0 if SEV is not supported, and 1 if SEV is supported on
+ * the platform.
+ */
 int
 qemuMonitorJSONGetSEVCapabilities(qemuMonitorPtr mon,
                                   virSEVCapability **capabilities)
@@ -6284,8 +6298,7 @@ qemuMonitorJSONGetSEVCapabilities(qemuMo
     if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
         goto cleanup;
 
-    /* Both -object sev-guest and query-sev-capabilities can be present
-     * even if SEV is not available */
+    /* QEMU has only compiled-in support of SEV */
     if (qemuMonitorJSONHasError(reply, "GenericError")) {
         ret = 0;
         goto cleanup;
@@ -6337,8 +6350,7 @@ qemuMonitorJSONGetSEVCapabilities(qemuMo
     capability->cbitpos = cbitpos;
     capability->reduced_phys_bits = reduced_phys_bits;
     VIR_STEAL_PTR(*capabilities, capability);
-    ret = 0;
-
+    ret = 1;
  cleanup:
     virSEVCapabilitiesFree(capability);
     virJSONValueFree(cmd);