[PATCH] target/i386/cpu: disable PERFCORE for AMD when cpu.pmu is off

[Liang Yan]

With cpu.pmu=off, perfctr_core could still be seen in an AMD guest cpuid.
By further digging, I found cpu.perfctr_core did the trick. However,
considering the 'enable_pmu' in KVM could work on both Intel and AMD,
we may add AMD PMU control under 'enabe_pmu' in QEMU too.

This change will overide the property 'perfctr_ctr' and change the AMD PMU
to off by default.

Signed-off-by: Liang Yan <lyan@digtalocean.com>
---
 target/i386/cpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 22b681ca37..edf5413c90 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5706,6 +5706,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
                 *ecx |= 1 << 1;    /* CmpLegacy bit */
             }
         }
+
+        if (!cpu->enable_pmu) {
+            *ecx &= ~CPUID_EXT3_PERFCORE;
+        }
         break;
     case 0x80000002:
     case 0x80000003:
-- 
2.34.1