From 3ff107d00519e66ee350f34fcad7739df32411a5 Mon Sep 17 00:00:00 2001
Message-Id: <3ff107d00519e66ee350f34fcad7739df32411a5@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Thu, 23 Apr 2020 20:59:53 +0200
Subject: [PATCH] =?UTF-8?q?RHEL:=20Fix=20migration=20on=20AMD=C2=A0hosts?=
 =?UTF-8?q?=20with=20old=20QEMU?=
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Fix for a RHEL-only hack for qemu-kvm-1.5.3-*

Downstream commit 6244ce5a6f started adding virt-ssbd feature to all
host-model CPUs before starting a domain to make sure it is enabled if
possible (qemu-kvm-1.5.3-* is too old for probing whether virt-ssbd may
be enabled, we just have to try). However, we add this feature to the
CPU definition before the definition is copied to priv->origCPU and the
definition stored there is used with QEMU older than 2.10 to start the
domain after it's been saved or during migration. And because the CPU
definition contains virt-ssbd which is not provided by the host CPU,
starting or migrating fails with

    the CPU is incompatible with host CPU: Host CPU does not provide
    required features: virt-ssbd

We need to copy the original CPU definition to priv->origCPU before
adding virt-ssbd there (normally priv->origCPU is set in
qemuProcessUpdateLiveGuestCPU when QEMU is already running).

https://bugzilla.redhat.com/show_bug.cgi?id=1815572

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Message-Id: <e4a8522926cad816fcfb60a05f1c28493ddbcd63.1587659979.git.jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_process.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 7a7fc8f205..ea55ccf7ec 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -5776,10 +5776,11 @@ qemuProcessSetupHotpluggableVcpus(virQEMUDriverPtr driver,
 
 static int
 qemuProcessUpdateGuestCPU(virDomainDefPtr def,
-                          virQEMUCapsPtr qemuCaps,
+                          qemuDomainObjPrivatePtr priv,
                           virCapsPtr caps,
                           unsigned int flags)
 {
+    virQEMUCapsPtr qemuCaps = priv->qemuCaps;
     int ret = -1;
     bool host_model = false;
 
@@ -5846,8 +5847,12 @@ qemuProcessUpdateGuestCPU(virDomainDefPtr def,
         virCPUDefPtr hostCPU;
         hostCPU = virQEMUCapsGetHostModel(qemuCaps, def->virtType,
                                          VIR_QEMU_CAPS_HOST_CPU_REPORTED);
-        if (hostCPU->fallback == VIR_CPU_FALLBACK_ALLOW)
+        if (hostCPU->fallback == VIR_CPU_FALLBACK_ALLOW) {
+            if (!priv->origCPU && !(priv->origCPU = virCPUDefCopy(def->cpu)))
+                goto cleanup;
+
             virCPUDefUpdateFeature(def->cpu, "virt-ssbd", VIR_CPU_FEATURE_REQUIRE);
+        }
     }
 
     def->cpu->fallback = VIR_CPU_FALLBACK_FORBID;
@@ -6069,7 +6074,7 @@ qemuProcessPrepareDomain(virQEMUDriverPtr driver,
     priv->runningReason = VIR_DOMAIN_RUNNING_UNKNOWN;
 
     VIR_DEBUG("Updating guest CPU definition");
-    if (qemuProcessUpdateGuestCPU(vm->def, priv->qemuCaps, caps, flags) < 0)
+    if (qemuProcessUpdateGuestCPU(vm->def, priv, caps, flags) < 0)
         goto cleanup;
 
     for (i = 0; i < vm->def->nshmems; i++) {
-- 
2.26.0