RFC NOTE: we need to confirm if all Westmere/SandyBridge/IvyBridge CPUs out there support PCID, before applying this patch.
RFC NOTE 2: in parallel, we are evaluating the possibility of enabling PCID on the existing Westmere/SandyBridge/IvyBridge CPU models, see https://patchew.org/QEMU/20180108205052.24385-1-vinc...@bernat.im/ and https://patchew.org/QEMU/20180109070112.30806-1-vinc...@bernat.im/ PCID was already available on Westmere, SandyBridge and IvyBridge, but we can't easily add it to the existing CPU models without breaking libvirt expectations about CPU model runnability (a runnable CPU model shouldn't become runnable just because of a machine-type or QEMU upgrade). However, Westmere-IBRS, SandyBridge-IBRS and IvyBridge-IBRS are new CPU models, so we can safely add PCID to them. Note that PCID is not necessary to mitigate Meltdown and/or Spectre, but it is really helpful to make performance not suffer when enabling KPTI on guest kernels. Cc: Jiri Denemark <jdene...@redhat.com> Suggested-by: Vincent Bernat <vinc...@bernat.im> Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> --- target/i386/cpu.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 9c36f9bd44..ad79fbb111 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1119,6 +1119,7 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_PGE | CPUID_MTRR | CPUID_SEP | CPUID_APIC | CPUID_CX8 | CPUID_MCE | CPUID_PAE | CPUID_MSR | CPUID_TSC | CPUID_PSE | CPUID_DE | CPUID_FP87, + /* Missing: CPUID_EXT_PCID */ .features[FEAT_1_ECX] = CPUID_EXT_AES | CPUID_EXT_POPCNT | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | @@ -1148,7 +1149,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_ECX] = CPUID_EXT_AES | CPUID_EXT_POPCNT | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | - CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3, + CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3 | CPUID_EXT_PCID, .features[FEAT_8000_0001_EDX] = CPUID_EXT2_LM | CPUID_EXT2_SYSCALL | CPUID_EXT2_NX, .features[FEAT_8000_0001_ECX] = @@ -1173,6 +1174,7 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_PGE | CPUID_MTRR | CPUID_SEP | CPUID_APIC | CPUID_CX8 | CPUID_MCE | CPUID_PAE | CPUID_MSR | CPUID_TSC | CPUID_PSE | CPUID_DE | CPUID_FP87, + /* Missing: CPUID_EXT_PCID */ .features[FEAT_1_ECX] = CPUID_EXT_AVX | CPUID_EXT_XSAVE | CPUID_EXT_AES | CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_POPCNT | @@ -1209,7 +1211,7 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_POPCNT | CPUID_EXT_X2APIC | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ | - CPUID_EXT_SSE3, + CPUID_EXT_SSE3 | CPUID_EXT_PCID, .features[FEAT_8000_0001_EDX] = CPUID_EXT2_LM | CPUID_EXT2_RDTSCP | CPUID_EXT2_NX | CPUID_EXT2_SYSCALL, @@ -1237,6 +1239,7 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_PGE | CPUID_MTRR | CPUID_SEP | CPUID_APIC | CPUID_CX8 | CPUID_MCE | CPUID_PAE | CPUID_MSR | CPUID_TSC | CPUID_PSE | CPUID_DE | CPUID_FP87, + /* Missing: CPUID_EXT_PCID */ .features[FEAT_1_ECX] = CPUID_EXT_AVX | CPUID_EXT_XSAVE | CPUID_EXT_AES | CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_POPCNT | @@ -1276,7 +1279,7 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_POPCNT | CPUID_EXT_X2APIC | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ | - CPUID_EXT_SSE3 | CPUID_EXT_F16C | CPUID_EXT_RDRAND, + CPUID_EXT_SSE3 | CPUID_EXT_F16C | CPUID_EXT_RDRAND | CPUID_EXT_PCID, .features[FEAT_7_0_EBX] = CPUID_7_0_EBX_FSGSBASE | CPUID_7_0_EBX_SMEP | CPUID_7_0_EBX_ERMS, -- 2.14.3
