From 5e1f4ab125d37efb4c8224184f4cd7dd7a0cfdcd Mon Sep 17 00:00:00 2001
Message-Id: <5e1f4ab125d37efb4c8224184f4cd7dd7a0cfdcd@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Fri, 22 Nov 2019 11:19:22 +0100
Subject: [PATCH] qemu: Drop disabled CPU features unknown to QEMU
MIME-Version: 1.0
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When a CPU definition wants to explicitly disable some features that are
unknown to QEMU, we can safely drop them from the definition before
starting QEMU. Naturally QEMU won't enable such features implicitly.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit ac34e141596fab70fbe91a396311f80db6cb57c5)

https://bugzilla.redhat.com/show_bug.cgi?id=1775133
https://bugzilla.redhat.com/show_bug.cgi?id=1775134
https://bugzilla.redhat.com/show_bug.cgi?id=1775137

Conflicts:
	src/qemu/qemu_process.c
            - downstream still uses cleanup label

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Message-Id: <1c07cf7bb969d38770555e7369d4578ba57bd38c.1574417839.git.jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_process.c                       | 32 +++++++++++++++++++
 ...-Icelake-Server-pconfig.x86_64-latest.args |  2 +-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 0cd61f02bb..0700b054f3 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -5730,6 +5730,26 @@ qemuProcessSetupHotpluggableVcpus(virQEMUDriverPtr driver,
 }
 
 
+static bool
+qemuProcessDropUnknownCPUFeatures(const char *name,
+                                  virCPUFeaturePolicy policy,
+                                  void *opaque)
+{
+    const char **features = opaque;
+
+    if (policy != VIR_CPU_FEATURE_DISABLE &&
+        policy != VIR_CPU_FEATURE_FORBID)
+        return true;
+
+    if (virStringListHasString(features, name))
+        return true;
+
+    /* Features unknown to QEMU are implicitly disabled, we can just drop them
+     * from the definition. */
+    return false;
+}
+
+
 static int
 qemuProcessUpdateGuestCPU(virDomainDefPtr def,
                           virQEMUCapsPtr qemuCaps,
@@ -5792,6 +5812,18 @@ qemuProcessUpdateGuestCPU(virDomainDefPtr def,
                         virQEMUCapsGetCPUDefinitions(qemuCaps, def->virtType)) < 0)
         goto cleanup;
 
+    if (ARCH_IS_X86(def->os.arch)) {
+        VIR_AUTOSTRINGLIST features = NULL;
+
+        if (virQEMUCapsGetCPUFeatures(qemuCaps, def->virtType, false, &features) < 0)
+            goto cleanup;
+
+        if (features &&
+            virCPUDefFilterFeatures(def->cpu, qemuProcessDropUnknownCPUFeatures,
+                                    features) < 0)
+            goto cleanup;
+    }
+
     def->cpu->fallback = VIR_CPU_FALLBACK_FORBID;
     ret = 0;
 
diff --git a/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64-latest.args b/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64-latest.args
index 664db44e7b..de737bfed7 100644
--- a/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64-latest.args
+++ b/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64-latest.args
@@ -10,7 +10,7 @@ QEMU_AUDIO_DRV=none \
 -object secret,id=masterKey0,format=raw,\
 file=/tmp/lib/domain--1-test/master-key.aes \
 -machine pc,accel=kvm,usb=off,dump-guest-core=off \
--cpu Icelake-Server,pconfig=off \
+-cpu Icelake-Server \
 -m 214 \
 -realtime mlock=off \
 -smp 1,sockets=1,cores=1,threads=1 \
-- 
2.24.0