[libvirt] [PATCH v2 0/3] Use non-blacklisted family/model/stepping for Haswell CPU model
Changes v1 -> v2: * Coding style fixes * Make series simpler: * Don't use trick: char vendor[static (CPUID_VENDOR_SZ + 1)] because it confuses checkpatch.pl * Removed patch "Add explicit array size to x86_cpu_vendor_words2str()" * Rebased on top of my x86-next branch: https://github.com/ehabkost/qemu x86-next Git branch for testing: https://github.com/ehabkost/qemu-hacks work/x86-rtm-blacklist Diff from v1: diff --git a/target/i386/cpu.h b/target/i386/cpu.h index cd94726e43..647435a1d9 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1431,7 +1431,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, void cpu_clear_apic_feature(CPUX86State *env); void host_cpuid(uint32_t function, uint32_t count, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx); -void host_vendor_fms(char vendor[static (CPUID_VENDOR_SZ + 1)], int *family, int *model, int *stepping); +void host_vendor_fms(char *vendor, int *family, int *model, int *stepping); /* helper.c */ int x86_cpu_handle_mmu_fault(CPUState *cpu, vaddr addr, diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 25c6c5e115..eab1ad7935 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -682,7 +682,7 @@ void host_cpuid(uint32_t function, uint32_t count, *edx = vec[3]; } -void host_vendor_fms(char vendor[static (CPUID_VENDOR_SZ + 1)], int *family, int *model, int *stepping) +void host_vendor_fms(char *vendor, int *family, int *model, int *stepping) { uint32_t eax, ebx, ecx, edx; @@ -1570,7 +1570,8 @@ static void host_x86_cpu_class_init(ObjectClass *oc, void *data) xcc->kvm_required = true; xcc->ordering = 9; - host_vendor_fms(host_cpudef.vendor, &host_cpudef.family, &host_cpudef.model, &host_cpudef.stepping); + host_vendor_fms(host_cpudef.vendor, &host_cpudef.family, + &host_cpudef.model, &host_cpudef.stepping); cpu_x86_fill_model_id(host_cpudef.model_id); --- A recent glibc commit[1] added a blacklist to ensure it won't use TSX on hosts that are known to have a broken TSX implementation. Our existing Haswell CPU model has a blacklisted family/model/stepping combination, so it has to be updated to make sure guests will really use TSX. This is done by patch 5/5. However, to do this safely we need to ensure the host CPU is not a blacklisted one, so we won't mislead guests by exposing known-to-be-good FMS values on a known-to-be-broken host. This is done by patch 3/5. [1] https://sourceware.org/git/?p=glibc.git;a=commit;h=2702856bf45c82cf8e69f2064... --- Cc: dgilbert@redhat.com Cc: fweimer@redhat.com Cc: carlos@redhat.com Cc: triegel@redhat.com Cc: berrange@redhat.com Cc: jdenemar@redhat.com Cc: pbonzini@redhat.com Eduardo Habkost (3): i386: host_vendor_fms() helper function i386/kvm: Blacklist TSX on known broken hosts i386: Change stepping of Haswell to non-blacklisted value include/hw/i386/pc.h | 5 +++++ target/i386/cpu.h | 1 + target/i386/cpu.c | 31 ++++++++++++++++++++++--------- target/i386/kvm.c | 17 +++++++++++++++++ 4 files changed, 45 insertions(+), 9 deletions(-) -- 2.11.0.259.g40922b1
Helper function for code that needs to check the host CPU vendor/family/model/stepping values. Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- Changes v1 -> v2: * Coding style fix (split long lines) --- target/i386/cpu.h | 1 + target/i386/cpu.c | 29 +++++++++++++++++++++-------- 2 files changed, 22 insertions(+), 8 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 5f75ab1b15..647435a1d9 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1431,6 +1431,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, void cpu_clear_apic_feature(CPUX86State *env); void host_cpuid(uint32_t function, uint32_t count, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx); +void host_vendor_fms(char *vendor, int *family, int *model, int *stepping); /* helper.c */ int x86_cpu_handle_mmu_fault(CPUState *cpu, vaddr addr, diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 7a04e6ff34..a8e4f37e27 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -682,6 +682,25 @@ void host_cpuid(uint32_t function, uint32_t count, *edx = vec[3]; } +void host_vendor_fms(char *vendor, int *family, int *model, int *stepping) +{ + uint32_t eax, ebx, ecx, edx; + + host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx); + x86_cpu_vendor_words2str(vendor, ebx, edx, ecx); + + host_cpuid(0x1, 0, &eax, &ebx, &ecx, &edx); + if (family) { + *family = ((eax >> 8) & 0x0F) + ((eax >> 20) & 0xFF); + } + if (model) { + *model = ((eax >> 4) & 0x0F) | ((eax & 0xF0000) >> 12); + } + if (stepping) { + *stepping = eax & 0x0F; + } +} + /* CPU class name definitions: */ #define X86_CPU_TYPE_SUFFIX "-" TYPE_X86_CPU @@ -1547,18 +1566,12 @@ static void host_x86_cpu_class_init(ObjectClass *oc, void *data) { DeviceClass *dc = DEVICE_CLASS(oc); X86CPUClass *xcc = X86_CPU_CLASS(oc); - uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0; xcc->kvm_required = true; xcc->ordering = 9; - host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx); - x86_cpu_vendor_words2str(host_cpudef.vendor, ebx, edx, ecx); - - host_cpuid(0x1, 0, &eax, &ebx, &ecx, &edx); - host_cpudef.family = ((eax >> 8) & 0x0F) + ((eax >> 20) & 0xFF); - host_cpudef.model = ((eax >> 4) & 0x0F) | ((eax & 0xF0000) >> 12); - host_cpudef.stepping = eax & 0x0F; + host_vendor_fms(host_cpudef.vendor, &host_cpudef.family, + &host_cpudef.model, &host_cpudef.stepping); cpu_x86_fill_model_id(host_cpudef.model_id); -- 2.11.0.259.g40922b1
Some Intel CPUs are known to have a broken TSX implementation. A microcode update from Intel disabled TSX on those CPUs, but GET_SUPPORTED_CPUID might be reporting it as supported if the hosts were not updated yet. Manually fixup the GET_SUPPORTED_CPUID data to ensure we will never enable TSX when running on those hosts. Reference: * glibc commit 2702856bf45c82cf8e69f2064f5aa15c0ceb6359: https://sourceware.org/git/?p=glibc.git;a=commit;h=2702856bf45c82cf8e69f2064... Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- target/i386/kvm.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 27fd0505df..2694f35e74 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -273,6 +273,19 @@ static int get_para_features(KVMState *s) return features; } +static bool host_tsx_blacklisted(void) +{ + int family, model, stepping;\ + char vendor[CPUID_VENDOR_SZ + 1]; + + host_vendor_fms(vendor, &family, &model, &stepping); + + /* Check if we are running on a Haswell host known to have broken TSX */ + return !strcmp(vendor, CPUID_VENDOR_INTEL) && + (family == 6) && + ((model == 63 && stepping < 4) || + model == 60 || model == 69 || model == 70); +} /* Returns the value for a specific register on the cpuid entry */ @@ -356,6 +369,10 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, } } else if (function == 6 && reg == R_EAX) { ret |= CPUID_6_EAX_ARAT; /* safe to allow because of emulated APIC */ + } else if (function == 7 && index == 0 && reg == R_EBX) { + if (host_tsx_blacklisted()) { + ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); + } } else if (function == 0x80000001 && reg == R_EDX) { /* On Intel, kvm returns cpuid according to the Intel spec, * so add missing bits according to the AMD spec: -- 2.11.0.259.g40922b1
glibc blacklists TSX on Haswell CPUs with model==60 and stepping < 4. To make the Haswell CPU model more useful, make those guests actually use TSX by changing CPU stepping to 4. References: * glibc commit 2702856bf45c82cf8e69f2064f5aa15c0ceb6359 https://sourceware.org/git/?p=glibc.git;a=commit;h=2702856bf45c82cf8e69f2064... Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- include/hw/i386/pc.h | 5 +++++ target/i386/cpu.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 079e8d9393..2ada479138 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -390,6 +390,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); .driver = TYPE_X86_CPU,\ .property = "vmware-cpuid-freq",\ .value = "off",\ + },\ + {\ + .driver = "Haswell-" TYPE_X86_CPU,\ + .property = "stepping",\ + .value = "1",\ }, #define PC_COMPAT_2_7 \ diff --git a/target/i386/cpu.c b/target/i386/cpu.c index a8e4f37e27..eab1ad7935 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1190,7 +1190,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .vendor = CPUID_VENDOR_INTEL, .family = 6, .model = 60, - .stepping = 1, + .stepping = 4, .features[FEAT_1_EDX] = CPUID_VME | CPUID_SSE2 | CPUID_SSE | CPUID_FXSR | CPUID_MMX | CPUID_CLFLUSH | CPUID_PSE36 | CPUID_PAT | CPUID_CMOV | CPUID_MCA | -- 2.11.0.259.g40922b1
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Eduardo Habkost