[libvirt] [PATCHv3] Add invariant TSC cpu flag

Add suport for invariant TSC flag (CPUID 0x80000007, bit 8 of EDX). If this flag is enabled, the TSC ticks at a constant rate across all ACPI P-, C- and T-states. This can be enabled by adding: <feature name='invtsc'/> to the <cpu> element. Migration and saving the domain does not work with this flag. QEMU support for this is not merged yet: https://lists.gnu.org/archive/html/qemu-devel/2014-04/msg05024.html The feature name "invtsc" differs from the name "" used by the linux kernel: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch... --- v1: https://www.redhat.com/archives/libvir-list/2014-May/msg00183.html v2: https://www.redhat.com/archives/libvir-list/2014-May/msg00297.html add it as a cpu flag instead of a timer v3: check if the feature wasn't filtered out on domain startup src/cpu/cpu_map.xml | 5 +++++ src/qemu/qemu_migration.c | 14 ++++++++++++++ src/qemu/qemu_process.c | 15 +++++++++++++++ 3 files changed, 34 insertions(+) diff --git a/src/cpu/cpu_map.xml b/src/cpu/cpu_map.xml index 7d34d40..ffaeb92 100644 --- a/src/cpu/cpu_map.xml +++ b/src/cpu/cpu_map.xml @@ -327,6 +327,11 @@ <cpuid function='0x00000007' ebx='0x00100000'/> </feature> + <!-- Advanced Power Management edx features --> + <feature name='invtsc'> + <cpuid function='0x80000007' edx='0x00000100'/> + </feature> + <!-- models --> <model name='486'> <feature name='fpu'/> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index f0df1a6..7504a38 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -1513,6 +1513,20 @@ qemuMigrationIsAllowed(virQEMUDriverPtr driver, virDomainObjPtr vm, return false; } + for (i = 0; i < def->cpu->nfeatures; i++) { + virCPUFeatureDefPtr feature = &def->cpu->features[i]; + + if (feature->policy != VIR_CPU_FEATURE_REQUIRE) + continue; + + if (STREQ(feature->name, "invtsc")) { + virReportError(VIR_ERR_OPERATION_INVALID, + _("domain has CPU feature: %s"), + feature->name); + return false; + } + } + return true; } diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index a83780f..0824afe 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -3568,6 +3568,7 @@ qemuProcessVerifyGuestCPU(virQEMUDriverPtr driver, virDomainObjPtr vm) qemuDomainObjPrivatePtr priv = vm->privateData; int rc; bool ret = false; + size_t i; switch (arch) { case VIR_ARCH_I686: @@ -3590,6 +3591,20 @@ qemuProcessVerifyGuestCPU(virQEMUDriverPtr driver, virDomainObjPtr vm) goto cleanup; } } + + for (i = 0; i < def->cpu->nfeatures; i++) { + virCPUFeatureDefPtr feature = &def->cpu->features[i]; + + if (feature->policy != VIR_CPU_FEATURE_REQUIRE) + continue; + + if (STREQ(feature->name, "invtsc") && + !cpuHasFeature(guestcpu, feature->name)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("host doesn't support invariant TSC")); + goto cleanup; + } + } break; default: -- 1.8.3.2