[v2,2/4] i386/cpu: Add PerfMonV2 feature bit

Commit Message

Moger, Babu Aug. 7, 2024, 10:15 p.m. UTC

From: Sandipan Das <[e-mail]>

CPUID leaf 0x80000022, i.e. ExtPerfMonAndDbg, advertises new performance
monitoring features for AMD processors. Bit 0 of EAX indicates support
for Performance Monitoring Version 2 (PerfMonV2) features. If found to
be set during PMU initialization, the EBX bits can be used to determine
the number of available counters for different PMUs. It also denotes the
availability of global control and status registers.

Add the required CPUID feature word and feature bit to allow guests to
make use of the PerfMonV2 features.

Signed-off-by: Sandipan Das <[e-mail]>
Signed-off-by: Babu Moger <[e-mail]>
Reviewed-by: Zhao Liu <[e-mail]>
---
v2: Used OR instead of overwrite for eax and ebx.
    Added Zhao's Reviewed-by.
---
 target/i386/cpu.c | 26 ++++++++++++++++++++++++++
 target/i386/cpu.h |  4 ++++
 2 files changed, 30 insertions(+)

Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 19ea14c1ff..44cac5fdc9 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1228,6 +1228,22 @@  FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .tcg_features = 0,
         .unmigratable_flags = 0,
     },
+    [FEAT_8000_0022_EAX] = {
+        .type = CPUID_FEATURE_WORD,
+        .feat_names = {
+            "perfmon-v2", NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+        },
+        .cpuid = { .eax = 0x80000022, .reg = R_EAX, },
+        .tcg_features = 0,
+        .unmigratable_flags = 0,
+    },
     [FEAT_XSAVE] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {
@@ -7038,6 +7054,16 @@  void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *edx = 0;
         }
         break;
+    case 0x80000022:
+        *eax = *ebx = *ecx = *edx = 0;
+        /* AMD Extended Performance Monitoring and Debug */
+        if (kvm_enabled() && cpu->enable_pmu &&
+            (env->features[FEAT_8000_0022_EAX] & CPUID_8000_0022_EAX_PERFMON_V2)) {
+            *eax |= CPUID_8000_0022_EAX_PERFMON_V2;
+            *ebx |= kvm_arch_get_supported_cpuid(cs->kvm_state, index, count,
+                                                 R_EBX) & 0xf;
+        }
+        break;
     case 0xC0000000:
         *eax = env->cpuid_xlevel2;
         *ebx = 0;
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index c6cc035df3..549752575e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -638,6 +638,7 @@  typedef enum FeatureWord {
     FEAT_8000_0007_EDX, /* CPUID[8000_0007].EDX */
     FEAT_8000_0008_EBX, /* CPUID[8000_0008].EBX */
     FEAT_8000_0021_EAX, /* CPUID[8000_0021].EAX */
+    FEAT_8000_0022_EAX, /* CPUID[8000_0022].EAX */
     FEAT_C000_0001_EDX, /* CPUID[C000_0001].EDX */
     FEAT_KVM,           /* CPUID[4000_0001].EAX (KVM_CPUID_FEATURES) */
     FEAT_KVM_HINTS,     /* CPUID[4000_0001].EDX */
@@ -1022,6 +1023,9 @@  uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w);
 /* Automatic IBRS */
 #define CPUID_8000_0021_EAX_AUTO_IBRS   (1U << 8)
 
+/* Performance Monitoring Version 2 */
+#define CPUID_8000_0022_EAX_PERFMON_V2  (1U << 0)
+
 #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
 #define CPUID_XSAVE_XSAVEC     (1U << 1)
 #define CPUID_XSAVE_XGETBV1    (1U << 2)