[libvirt] [QEMU PATCH] target-i386: Disable rdtscp on Opteron_G* CPU models
KVM can't virtualize rdtscp on AMD CPUs yet, so there's no point in enabling it by default on AMD CPU models, as all we are getting are confused users because of the "host doesn't support requested feature" warnings. Disable rdtscp on Opteron_G* models, but keep compatibility on pc-*-2.4 and older (just in case there are people are doing funny stuff using AMD CPU models on Intel hosts). Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- include/hw/i386/pc.h | 17 +++++++++++++++++ target-i386/cpu.c | 12 ++++++++---- 2 files changed, 25 insertions(+), 4 deletions(-) diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 4bbc0ff..854c330 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -347,8 +347,25 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); .driver = "qemu32" "-" TYPE_X86_CPU,\ .property = "popcnt",\ .value = "on",\ + },{\ + .driver = "Opteron_G2" "-" TYPE_X86_CPU,\ + .property = "rdtscp",\ + .value = "on",\ + },{\ + .driver = "Opteron_G3" "-" TYPE_X86_CPU,\ + .property = "rdtscp",\ + .value = "on",\ + },{\ + .driver = "Opteron_G4" "-" TYPE_X86_CPU,\ + .property = "rdtscp",\ + .value = "on",\ + },{\ + .driver = "Opteron_G5" "-" TYPE_X86_CPU,\ + .property = "rdtscp",\ + .value = "on",\ }, + #define PC_COMPAT_2_3 \ PC_COMPAT_2_4 \ HW_COMPAT_2_3 \ diff --git a/target-i386/cpu.c b/target-i386/cpu.c index e5f1c5b..11e5e39 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -1244,8 +1244,9 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_DE | CPUID_FP87, .features[FEAT_1_ECX] = CPUID_EXT_CX16 | CPUID_EXT_SSE3, + /* Missing: CPUID_EXT2_RDTSCP */ .features[FEAT_8000_0001_EDX] = - CPUID_EXT2_LM | CPUID_EXT2_RDTSCP | CPUID_EXT2_FXSR | + CPUID_EXT2_LM | CPUID_EXT2_FXSR | CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE | CPUID_EXT2_MTRR | CPUID_EXT2_SYSCALL | @@ -1273,8 +1274,9 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_ECX] = CPUID_EXT_POPCNT | CPUID_EXT_CX16 | CPUID_EXT_MONITOR | CPUID_EXT_SSE3, + /* Missing: CPUID_EXT2_RDTSCP */ .features[FEAT_8000_0001_EDX] = - CPUID_EXT2_LM | CPUID_EXT2_RDTSCP | CPUID_EXT2_FXSR | + CPUID_EXT2_LM | CPUID_EXT2_FXSR | CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE | CPUID_EXT2_MTRR | CPUID_EXT2_SYSCALL | @@ -1305,8 +1307,9 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_EXT_POPCNT | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3, + /* Missing: CPUID_EXT2_RDTSCP */ .features[FEAT_8000_0001_EDX] = - CPUID_EXT2_LM | CPUID_EXT2_RDTSCP | + CPUID_EXT2_LM | CPUID_EXT2_PDPE1GB | CPUID_EXT2_FXSR | CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE | @@ -1340,8 +1343,9 @@ static X86CPUDefinition builtin_x86_defs[] = { CPUID_EXT_AES | CPUID_EXT_POPCNT | CPUID_EXT_SSE42 | CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_FMA | CPUID_EXT_SSSE3 | CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3, + /* Missing: CPUID_EXT2_RDTSCP */ .features[FEAT_8000_0001_EDX] = - CPUID_EXT2_LM | CPUID_EXT2_RDTSCP | + CPUID_EXT2_LM | CPUID_EXT2_PDPE1GB | CPUID_EXT2_FXSR | CPUID_EXT2_MMX | CPUID_EXT2_NX | CPUID_EXT2_PSE36 | CPUID_EXT2_PAT | CPUID_EXT2_CMOV | CPUID_EXT2_MCA | CPUID_EXT2_PGE | -- 2.1.0
On 13/11/2015 20:07, Eduardo Habkost wrote:
KVM can't virtualize rdtscp on AMD CPUs yet, so there's no point in enabling it by default on AMD CPU models, as all we are getting are confused users because of the "host doesn't support requested feature" warnings.
Disable rdtscp on Opteron_G* models, but keep compatibility on pc-*-2.4 and older (just in case there are people are doing funny stuff using AMD CPU models on Intel hosts).
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Can we do it only on KVM and not on TCG? Paolo
On Mon, Nov 16, 2015 at 10:44:59AM +0100, Paolo Bonzini wrote:
On 13/11/2015 20:07, Eduardo Habkost wrote:
KVM can't virtualize rdtscp on AMD CPUs yet, so there's no point in enabling it by default on AMD CPU models, as all we are getting are confused users because of the "host doesn't support requested feature" warnings.
Disable rdtscp on Opteron_G* models, but keep compatibility on pc-*-2.4 and older (just in case there are people are doing funny stuff using AMD CPU models on Intel hosts).
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Can we do it only on KVM and not on TCG?
We can, but I would like to avoid it, if possible. It would require more complex compat code (the "Add optional class name to kvm_default_props¨ patch I sent some time ago), and people who need rdtscp will be able to use Opteron_G*-rdtscp soon. -- Eduardo
On Fri, Nov 13, 2015 at 05:07:13PM -0200, Eduardo Habkost wrote:
KVM can't virtualize rdtscp on AMD CPUs yet, so there's no point in enabling it by default on AMD CPU models, as all we are getting are confused users because of the "host doesn't support requested feature" warnings.
Disable rdtscp on Opteron_G* models, but keep compatibility on pc-*-2.4 and older (just in case there are people are doing funny stuff using AMD CPU models on Intel hosts).
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Applied to x86 tree. -- Eduardo
participants (2)
-
Eduardo Habkost -
Paolo Bonzini