From: Zhao Liu <zhao1.liu@intel.com>
Date: Thu, 11 Dec 2025 06:07:47 +0000 (+0800)
Subject: i386/cpu: Drop pmu check in CPUID 0x1C encoding
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f2f0f76d04fe26c549384efd97740ac73455a66;p=thirdparty%2Fqemu.git

i386/cpu: Drop pmu check in CPUID 0x1C encoding

Since CPUID_7_0_EDX_ARCH_LBR will be masked off if pmu is disabled,
there's no need to check CPUID_7_0_EDX_ARCH_LBR feature with pmu.

Tested-by: Farrah Chen <farrah.chen@intel.com>
Reviewed-by: Zide Chen <zide.chen@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20251211060801.3600039-9-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index b53467eb99..5ba4d49dc3 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8273,11 +8273,16 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         }
         break;
     }
-    case 0x1C:
-        if (cpu->enable_pmu && (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
-            x86_cpu_get_supported_cpuid(0x1C, 0, eax, ebx, ecx, edx);
-            *edx = 0;
+    case 0x1C: /* Last Branch Records Information Leaf */
+        *eax = 0;
+        *ebx = 0;
+        *ecx = 0;
+        *edx = 0;
+        if (!(env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
+            break;
         }
+        x86_cpu_get_supported_cpuid(0x1C, 0, eax, ebx, ecx, edx);
+        *edx = 0; /* EDX is reserved. */
         break;
     case 0x1D: {
         /* AMX TILE, for now hardcoded for Sapphire Rapids*/