From: Xiaoyao Li <xiaoyao.li@intel.com>
Date: Wed, 25 Jun 2025 03:57:10 +0000 (+0800)
Subject: i386/tdx: Don't mask off CPUID_EXT_PDCM
X-Git-Tag: v10.1.0-rc0~21^2~38
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7ff24fb657d35c014f735f69aef03810fde607ab;p=thirdparty%2Fqemu.git

i386/tdx: Don't mask off CPUID_EXT_PDCM

It gets below warning when booting TDX VMs:

  warning: TDX forcibly sets the feature: CPUID[eax=01h].ECX.pdcm [bit 15]

Because CPUID_EXT_PDCM is fixed1 for TDX, and MSR_IA32_PERF_CAPABILITIES is
supported for TDX guest unconditioanlly.

Don't mask off CPUID_EXT_PDCM for TDX.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250625035710.2770679-1-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index b768838b10..f9e6bc8d0e 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -28,6 +28,7 @@
 #include "system/hvf.h"
 #include "hvf/hvf-i386.h"
 #include "kvm/kvm_i386.h"
+#include "kvm/tdx.h"
 #include "sev.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
@@ -8336,7 +8337,8 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
         }
     }
 
-    if (!cpu->enable_pmu) {
+    /* PDCM is fixed1 bit for TDX */
+    if (!cpu->enable_pmu && !is_tdx_vm()) {
         mark_unavailable_features(cpu, FEAT_1_ECX,
                                   env->user_features[FEAT_1_ECX] & CPUID_EXT_PDCM,
                                   "This feature is not available due to PMU being disabled");