[libvirt] [PATCH v2 6/7] qemu: Forbid MSR features with old QEMU
Without "unavailable-features" CPU property we cannot properly detect
whether a specific MSR feature we asked for (either explicitly or
implicitly via a CPU model) was disabled by QEMU for some reason.
Because this could break migration, snapshots, and save/restore
operaions, it's better to just forbid any use of MSR features with QEMU
which lacks "unavailable-features" CPU property.
Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com>
---
src/qemu/qemu_process.c | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index fa82adbc1e..45997dad49 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -59,6 +59,7 @@
#include "qemu_firmware.h"
#include "cpu/cpu.h"
+#include "cpu/cpu_x86.h"
#include "datatypes.h"
#include "virlog.h"
#include "virerror.h"
@@ -5407,9 +5408,31 @@ qemuProcessStartValidate(virQEMUDriverPtr driver,
if (qemuProcessStartValidateShmem(vm) < 0)
return -1;
- if (vm->def->cpu &&
- virCPUValidateFeatures(vm->def->os.arch, vm->def->cpu) < 0)
- return -1;
+ if (vm->def->cpu) {
+ if (virCPUValidateFeatures(vm->def->os.arch, vm->def->cpu) < 0)
+ return -1;
+
+ if (ARCH_IS_X86(vm->def->os.arch) &&
+ !virQEMUCapsGet(qemuCaps, QEMU_CAPS_CPU_UNAVAILABLE_FEATURES)) {
+ VIR_AUTOSTRINGLIST features = NULL;
+ int n;
+
+ if ((n = virCPUDefCheckFeatures(vm->def->cpu,
+ virCPUx86FeatureIsMSR, NULL,
+ &features)) < 0)
+ return -1;
+
+ if (n > 0) {
+ VIR_AUTOFREE(char *) str = NULL;
+
+ str = virStringListJoin((const char **)features, ", ");
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("Some features cannot be reliably used "
+ "with this QEMU: %s"), str);
+ return -1;
+ }
+ }
+ }
if (qemuProcessStartValidateDisks(vm, qemuCaps) < 0)
return -1;
--
2.22.0