[v3] target/i386/kvm/pmu: PMU Enhancement, Bugfix and Cleanup

[PATCH v3 02/10] target/i386: disable PERFCORE when "-pmu" is configured

Dongli Zhang posted 10 patches 10 months, 2 weeks ago

Diff against v2 v4 v5 v6 v7 v8 v9
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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Zhao Liu <zhao1.liu@intel.com>, Marcelo Tosatti <mtosatti@redhat.com>, Song Gao <gaosong@loongson.cn>, Huacai Chen <chenhuacai@kernel.org>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <arikalo@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Weiwei Li <liwei1518@gmail.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Richard Henderson <richard.henderson@linaro.org>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>

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[PATCH v3 02/10] target/i386: disable PERFCORE when "-pmu" is configured

Posted by Dongli Zhang 10 months, 2 weeks ago

Currently, AMD PMU support isn't determined based on CPUID, that is, the
"-pmu" option does not fully disable KVM AMD PMU virtualization.

To minimize AMD PMU features, remove PERFCORE when "-pmu" is configured.

To completely disable AMD PMU virtualization will be implemented via
KVM_CAP_PMU_CAPABILITY in upcoming patches.

As a reminder, neither CPUID_EXT3_PERFCORE nor
CPUID_8000_0022_EAX_PERFMON_V2 is removed from env->features[] when "-pmu"
is configured. Developers should query whether they are supported via
cpu_x86_cpuid() rather than relying on env->features[] in future patches.

Suggested-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
---
Changed since v2:
  - No need to check "kvm_enabled() && IS_AMD_CPU(env)".

 target/i386/cpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 2b87331be5..acbd627f7e 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -7242,6 +7242,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             !(env->hflags & HF_LMA_MASK)) {
             *edx &= ~CPUID_EXT2_SYSCALL;
         }
+
+        if (!cpu->enable_pmu) {
+            *ecx &= ~CPUID_EXT3_PERFCORE;
+        }
         break;
     case 0x80000002:
     case 0x80000003:
-- 
2.39.3