From 6a6f6b91e0e76480ea961f83135efcb4faf3284a Mon Sep 17 00:00:00 2001 From: Jiri Denemark Date: Fri, 6 Oct 2017 14:49:07 +0200 Subject: [PATCH] qemu: Fix CPU model broken by older libvirt When libvirt older than 3.9.0 reconnected to a running domain started by old libvirt it could have messed up the expansion of host-model by adding features QEMU does not support (such as cmt). Thus whenever we reconnect to a running domain, revert to an active snapshot, or restore a saved domain we need to check the guest CPU model and remove the CPU features unknown to QEMU. We can do this because we know the domain was successfully started, which means the CPU did not contain the features when libvirt started the domain. https://bugzilla.redhat.com/show_bug.cgi?id=1495171 Signed-off-by: Jiri Denemark Reviewed-by: Pavel Hrdina --- src/qemu/qemu_domain.c | 76 +++++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_domain.h | 4 +++ src/qemu/qemu_driver.c | 14 ++++++++ src/qemu/qemu_process.c | 9 +++++ 4 files changed, 103 insertions(+) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 173fbca6ed..05e8b96aa4 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -10027,6 +10027,82 @@ qemuDomainUpdateCPU(virDomainObjPtr vm, return 0; } + +/** + * qemuDomainFixupCPUS: + * @vm: domain object + * @origCPU: original CPU used when the domain was started + * + * Libvirt older than 3.9.0 could have messed up the expansion of host-model + * CPU when reconnecting to a running domain by adding features QEMU does not + * support (such as cmt). This API fixes both the actual CPU provided by QEMU + * (stored in the domain object) and the @origCPU used when starting the + * domain. + * + * This is safe even if the original CPU definition used mode='custom' (rather + * than host-model) since we know QEMU was able to start the domain and thus + * the CPU definitions do not contain any features unknown to QEMU. + * + * This function can only be used on an active domain or when restoring a + * domain which was running. + * + * Returns 0 on success, -1 on error. + */ +int +qemuDomainFixupCPUs(virDomainObjPtr vm, + virCPUDefPtr *origCPU) +{ + virCPUDefPtr fixedCPU = NULL; + virCPUDefPtr fixedOrig = NULL; + virArch arch = vm->def->os.arch; + int ret = 0; + + if (!ARCH_IS_X86(arch)) + return 0; + + if (!vm->def->cpu || + vm->def->cpu->mode != VIR_CPU_MODE_CUSTOM || + !vm->def->cpu->model) + return 0; + + /* Missing origCPU means QEMU created exactly the same virtual CPU which + * we asked for or libvirt was too old to mess up the translation from + * host-model. + */ + if (!*origCPU) + return 0; + + if (virCPUDefFindFeature(vm->def->cpu, "cmt") && + (!(fixedCPU = virCPUDefCopyWithoutModel(vm->def->cpu)) || + virCPUDefCopyModelFilter(fixedCPU, vm->def->cpu, false, + virQEMUCapsCPUFilterFeatures, &arch) < 0)) + goto cleanup; + + if (virCPUDefFindFeature(*origCPU, "cmt") && + (!(fixedOrig = virCPUDefCopyWithoutModel(*origCPU)) || + virCPUDefCopyModelFilter(fixedOrig, *origCPU, false, + virQEMUCapsCPUFilterFeatures, &arch) < 0)) + goto cleanup; + + if (fixedCPU) { + virCPUDefFree(vm->def->cpu); + VIR_STEAL_PTR(vm->def->cpu, fixedCPU); + } + + if (fixedOrig) { + virCPUDefFree(*origCPU); + VIR_STEAL_PTR(*origCPU, fixedOrig); + } + + ret = 0; + + cleanup: + virCPUDefFree(fixedCPU); + virCPUDefFree(fixedOrig); + return ret; +} + + char * qemuDomainGetMachineName(virDomainObjPtr vm) { diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index 00226a3fc8..5201c6a0ac 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -971,6 +971,10 @@ qemuDomainUpdateCPU(virDomainObjPtr vm, virCPUDefPtr cpu, virCPUDefPtr *origCPU); +int +qemuDomainFixupCPUs(virDomainObjPtr vm, + virCPUDefPtr *origCPU); + char * qemuDomainGetMachineName(virDomainObjPtr vm); diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 7c8ad32675..fb4d722368 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -6551,6 +6551,13 @@ qemuDomainSaveImageStartVM(virConnectPtr conn, } } + /* No cookie means libvirt which saved the domain was too old to mess up + * the CPU definitions. + */ + if (cookie && + qemuDomainFixupCPUs(vm, &cookie->cpu) < 0) + goto cleanup; + if (qemuProcessStart(conn, driver, vm, cookie ? cookie->cpu : NULL, asyncJob, "stdio", *fd, path, NULL, VIR_NETDEV_VPORT_PROFILE_OP_RESTORE, @@ -15756,6 +15763,13 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot, if (config) virDomainObjAssignDef(vm, config, false, NULL); + /* No cookie means libvirt which saved the domain was too old to + * mess up the CPU definitions. + */ + if (cookie && + qemuDomainFixupCPUs(vm, &cookie->cpu) < 0) + goto cleanup; + rc = qemuProcessStart(snapshot->domain->conn, driver, vm, cookie ? cookie->cpu : NULL, QEMU_ASYNC_JOB_START, NULL, -1, NULL, snap, diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index f1ad7ad1f1..e062194294 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -6881,6 +6881,7 @@ qemuProcessRefreshCPU(virQEMUDriverPtr driver, virDomainObjPtr vm) { virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false); + qemuDomainObjPrivatePtr priv = vm->privateData; virCPUDefPtr host = NULL; virCPUDefPtr cpu = NULL; int ret = -1; @@ -6915,6 +6916,14 @@ qemuProcessRefreshCPU(virQEMUDriverPtr driver, if (qemuProcessUpdateCPU(driver, vm, QEMU_ASYNC_JOB_NONE) < 0) goto cleanup; + } else if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION)) { + /* We only try to fix CPUs when the libvirt/QEMU combo used to start + * the domain did not know about query-cpu-model-expansion in which + * case the host-model is known to not contain features which QEMU + * doesn't know about. + */ + if (qemuDomainFixupCPUs(vm, &priv->origCPU) < 0) + goto cleanup; } ret = 0;