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Subject[Qemu-devel] [PATCH 1/2] target/i386: define a new MSR based feature word - FEAT_PERF_CAPABILITIES
Date
The Perfmon and Debug Capability MSR named IA32_PERF_CAPABILITIES is
a feature-enumerating MSR, which only enumerates the feature full-width
write (via bit 13) by now which indicates the processor supports IA32_A_PMCx
interface for updating bits 32 and above of IA32_PMCx.

The existence of MSR IA32_PERF_CAPABILITIES is enumerated by CPUID.1:ECX[15].

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: qemu-devel@nongnu.org
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20200529074347.124619-5-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
target/i386/cpu.c | 23 +++++++++++++++++++++++
target/i386/cpu.h | 3 +++
target/i386/kvm.c | 20 ++++++++++++++++++++
3 files changed, 46 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 02065e35d4..e47c9d1604 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1139,6 +1139,22 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
.index = MSR_IA32_CORE_CAPABILITY,
},
},
+ [FEAT_PERF_CAPABILITIES] = {
+ .type = MSR_FEATURE_WORD,
+ .feat_names = {
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, "full-width-write", NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ },
+ .msr = {
+ .index = MSR_IA32_PERF_CAPABILITIES,
+ },
+ },

[FEAT_VMX_PROCBASED_CTLS] = {
.type = MSR_FEATURE_WORD,
@@ -1316,6 +1332,10 @@ static FeatureDep feature_dependencies[] = {
.from = { FEAT_7_0_EDX, CPUID_7_0_EDX_CORE_CAPABILITY },
.to = { FEAT_CORE_CAPABILITY, ~0ull },
},
+ {
+ .from = { FEAT_1_ECX, CPUID_EXT_PDCM },
+ .to = { FEAT_PERF_CAPABILITIES, ~0ull },
+ },
{
.from = { FEAT_1_ECX, CPUID_EXT_VMX },
.to = { FEAT_VMX_PROCBASED_CTLS, ~0ull },
@@ -5488,6 +5508,9 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
*ebx |= (cs->nr_cores * cs->nr_threads) << 16;
*edx |= CPUID_HT;
}
+ if (!cpu->enable_pmu) {
+ *ecx &= ~CPUID_EXT_PDCM;
+ }
break;
case 2:
/* cache info: needed for Pentium Pro compatibility */
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 408392dbf6..fad2f874bd 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -356,6 +356,8 @@ typedef enum X86Seg {
#define MSR_IA32_ARCH_CAPABILITIES 0x10a
#define ARCH_CAP_TSX_CTRL_MSR (1<<7)

+#define MSR_IA32_PERF_CAPABILITIES 0x345
+
#define MSR_IA32_TSX_CTRL 0x122
#define MSR_IA32_TSCDEADLINE 0x6e0

@@ -529,6 +531,7 @@ typedef enum FeatureWord {
FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
FEAT_ARCH_CAPABILITIES,
FEAT_CORE_CAPABILITY,
+ FEAT_PERF_CAPABILITIES,
FEAT_VMX_PROCBASED_CTLS,
FEAT_VMX_SECONDARY_CTLS,
FEAT_VMX_PINBASED_CTLS,
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 34f838728d..9be6f76b2c 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -106,6 +106,7 @@ static bool has_msr_core_capabs;
static bool has_msr_vmx_vmfunc;
static bool has_msr_ucode_rev;
static bool has_msr_vmx_procbased_ctls2;
+static bool has_msr_perf_capabs;

static uint32_t has_architectural_pmu_version;
static uint32_t num_architectural_pmu_gp_counters;
@@ -2027,6 +2028,9 @@ static int kvm_get_supported_msrs(KVMState *s)
case MSR_IA32_CORE_CAPABILITY:
has_msr_core_capabs = true;
break;
+ case MSR_IA32_PERF_CAPABILITIES:
+ has_msr_perf_capabs = true;
+ break;
case MSR_IA32_VMX_VMFUNC:
has_msr_vmx_vmfunc = true;
break;
@@ -2643,6 +2647,18 @@ static void kvm_msr_entry_add_vmx(X86CPU *cpu, FeatureWordArray f)
VMCS12_MAX_FIELD_INDEX << 1);
}

+static void kvm_msr_entry_add_perf(X86CPU *cpu, FeatureWordArray f)
+{
+ uint64_t kvm_perf_cap =
+ kvm_arch_get_supported_msr_feature(kvm_state,
+ MSR_IA32_PERF_CAPABILITIES);
+
+ if (kvm_perf_cap) {
+ kvm_msr_entry_add(cpu, MSR_IA32_PERF_CAPABILITIES,
+ kvm_perf_cap & f[FEAT_PERF_CAPABILITIES]);
+ }
+}
+
static int kvm_buf_set_msrs(X86CPU *cpu)
{
int ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, cpu->kvm_msr_buf);
@@ -2675,6 +2691,10 @@ static void kvm_init_msrs(X86CPU *cpu)
env->features[FEAT_CORE_CAPABILITY]);
}

+ if (has_msr_perf_capabs && cpu->enable_pmu) {
+ kvm_msr_entry_add_perf(cpu, env->features);
+ }
+
if (has_msr_ucode_rev) {
kvm_msr_entry_add(cpu, MSR_IA32_UCODE_REV, cpu->ucode_rev);
}
--
2.21.3
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