On 3/3/2025 6:00 AM, Dongli Zhang wrote:
When the PERFCORE is disabled with "-cpu host,-perfctr-core", it is
reflected in in guest dmesg.
[ 0.285136] Performance Events: AMD PMU driver.
I'm a little confused. wWhen no perfctr-core, AMD PMU driver can still
be probed? (forgive me if I ask a silly question)
However, the guest CPUID indicates the PerfMonV2 is still available.
CPU:
Extended Performance Monitoring and Debugging (0x80000022):
AMD performance monitoring V2 = true
AMD LBR V2 = false
AMD LBR stack & PMC freezing = false
number of core perf ctrs = 0x6 (6)
number of LBR stack entries = 0x0 (0)
number of avail Northbridge perf ctrs = 0x0 (0)
number of available UMC PMCs = 0x0 (0)
active UMCs bitmask = 0x0
Disable PerfMonV2 in CPUID when PERFCORE is disabled.
Suggested-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
Though I have above confusion of the description, the change itself
looks good to me. So
Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Fixes: 209b0ac12074 ("target/i386: Add PerfMonV2 feature bit")
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
Changed since v1:
- Use feature_dependencies (suggested by Zhao Liu).
target/i386/cpu.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 72ab147e85..b6d6167910 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1805,6 +1805,10 @@ static FeatureDep feature_dependencies[] = {
.from = { FEAT_7_1_EDX, CPUID_7_1_EDX_AVX10 },
.to = { FEAT_24_0_EBX, ~0ull },
},
+ {
+ .from = { FEAT_8000_0001_ECX, CPUID_EXT3_PERFCORE },
+ .to = { FEAT_8000_0022_EAX, CPUID_8000_0022_EAX_PERFMON_V2 },
+ },
};
typedef struct X86RegisterInfo32 {
