From: Zhao Liu <zhao1.liu@intel.com>
Date: Thu, 11 Dec 2025 06:07:45 +0000 (+0800)
Subject: i386/cpu: Use x86_ext_save_areas[] for CPUID.0XD subleaves
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d88caf0954dfc7598a7db27c2cc98937c7ad6ead;p=thirdparty%2Fqemu.git

i386/cpu: Use x86_ext_save_areas[] for CPUID.0XD subleaves

The x86_ext_save_areas[] is expected to be well initialized by
accelerators and its xstate detail information cannot be changed by
user. So use x86_ext_save_areas[] to encode CPUID.0XD subleaves directly
without other hardcoding & masking.

And for arch LBR, KVM fills its xstate in x86_ext_save_areas[] via
host_cpuid(). The info obtained this way matches what would be retrieved
from x86_cpu_get_supported_cpuid() (since KVM just fills CPUID with the
host xstate info directly anyway). So just use the initialized
x86_ext_save_areas[] instead of calling x86_cpu_get_supported_cpuid().

Tested-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20251211060801.3600039-7-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 812a215147..f4c0ae533d 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8188,20 +8188,17 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             }
         } else if (count == 0xf && cpu->enable_pmu
                    && (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
-            x86_cpu_get_supported_cpuid(0xD, count, eax, ebx, ecx, edx);
+            const ExtSaveArea *esa = &x86_ext_save_areas[count];
+
+            *eax = esa->size;
+            *ebx = esa->offset;
+            *ecx = esa->ecx;
         } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {
             const ExtSaveArea *esa = &x86_ext_save_areas[count];
 
-            if (x86_cpu_xsave_xcr0_components(cpu) & (1ULL << count)) {
-                *eax = esa->size;
-                *ebx = esa->offset;
-                *ecx = esa->ecx &
-                       (ESA_FEATURE_ALIGN64_MASK | ESA_FEATURE_XFD_MASK);
-            } else if (x86_cpu_xsave_xss_components(cpu) & (1ULL << count)) {
-                *eax = esa->size;
-                *ebx = 0;
-                *ecx = 1;
-            }
+            *eax = esa->size;
+            *ebx = esa->offset;
+            *ecx = esa->ecx;
         }
         break;
     }