When PMU is disabled, guest CPUID must not advertise Debug Store
support.  Clear both CPUID.01H:EDX[21] (DS) and CPUID.01H:ECX[2]
(DS64) in this case.

Set IA32_MISC_ENABLE[12] (PEBS_UNAVAILABLE) when Debug Store is not
exposed to the guest.

Note: Do not infer that PEBS is unsupported from
IA32_PERF_CAPABILITIES[11:8] (PEBS_FMT) being 0.  A value of 0 is a
valid PEBS record format on some CPUs.

Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- New patch.

 target/i386/cpu.c | 6 ++++++
 target/i386/cpu.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index ec6f49916de3..445361ab7a06 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -9180,6 +9180,10 @@ static void x86_cpu_reset_hold(Object *obj, ResetType type)
         env->msr_ia32_misc_enable |= MSR_IA32_MISC_ENABLE_MWAIT;
     }
 
+    if (!(env->features[FEAT_1_EDX] & CPUID_DTS)) {
+        env->msr_ia32_misc_enable |= MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL;
+    }
+
     memset(env->dr, 0, sizeof(env->dr));
     env->dr[6] = DR6_FIXED_1;
     env->dr[7] = DR7_FIXED_1;
@@ -9474,6 +9478,8 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
             env->features[FEAT_1_ECX] &= ~CPUID_EXT_PDCM;
         }
 
+        env->features[FEAT_1_ECX] &= ~CPUID_EXT_DTES64;
+        env->features[FEAT_1_EDX] &= ~CPUID_DTS;
         env->features[FEAT_7_0_EDX] &= ~CPUID_7_0_EDX_ARCH_LBR;
     }
 
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 5ab107dfa29f..0fecf561173e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -483,6 +483,7 @@ typedef enum X86Seg {
 /* Indicates good rep/movs microcode on some processors: */
 #define MSR_IA32_MISC_ENABLE_FASTSTRING    (1ULL << 0)
 #define MSR_IA32_MISC_ENABLE_BTS_UNAVAIL   (1ULL << 11)
+#define MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL  (1ULL << 12)
 #define MSR_IA32_MISC_ENABLE_MWAIT      (1ULL << 18)
 #define MSR_IA32_MISC_ENABLE_DEFAULT    (MSR_IA32_MISC_ENABLE_FASTSTRING     |\
                                          MSR_IA32_MISC_ENABLE_BTS_UNAVAIL)
-- 
2.52.0