Track the mask of "unavailable" PMU events as a 32-bit value.  While bits
31:9 are currently reserved, silently truncating those bits is unnecessary
and asking for missed coverage.  To avoid running afoul of the sanity check
in vcpu_set_cpuid_property(), explicitly adjust the mask based on the
non-reserved bits as reported by KVM's supported CPUID.

Opportunistically update the "all ones" testcase to pass -1u instead of
0xff.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 tools/testing/selftests/kvm/x86/pmu_counters_test.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86/pmu_counters_test.c b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
index 8aaaf25b6111..cfeed0103341 100644
--- a/tools/testing/selftests/kvm/x86/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
@@ -311,7 +311,7 @@ static void guest_test_arch_events(void)
 }
 
 static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
-			     uint8_t length, uint8_t unavailable_mask)
+			     uint8_t length, uint32_t unavailable_mask)
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -320,6 +320,9 @@ static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
 	if (!pmu_version)
 		return;
 
+	unavailable_mask = GENMASK(X86_PROPERTY_PMU_EVENTS_MASK.hi_bit,
+				   X86_PROPERTY_PMU_EVENTS_MASK.lo_bit);
+
 	vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_test_arch_events,
 					 pmu_version, perf_capabilities);
 
@@ -630,7 +633,7 @@ static void test_intel_counters(void)
 			 */
 			for (j = 0; j <= NR_INTEL_ARCH_EVENTS + 1; j++) {
 				test_arch_events(v, perf_caps[i], j, 0);
-				test_arch_events(v, perf_caps[i], j, 0xff);
+				test_arch_events(v, perf_caps[i], j, -1u);
 
 				for (k = 0; k < NR_INTEL_ARCH_EVENTS; k++)
 					test_arch_events(v, perf_caps[i], j, BIT(k));
-- 
2.51.0.470.ga7dc726c21-goog

On 9/19/2025 8:45 AM, Sean Christopherson wrote:
> Track the mask of "unavailable" PMU events as a 32-bit value.  While bits
> 31:9 are currently reserved, silently truncating those bits is unnecessary
> and asking for missed coverage.  To avoid running afoul of the sanity check
> in vcpu_set_cpuid_property(), explicitly adjust the mask based on the
> non-reserved bits as reported by KVM's supported CPUID.
>
> Opportunistically update the "all ones" testcase to pass -1u instead of
> 0xff.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  tools/testing/selftests/kvm/x86/pmu_counters_test.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/x86/pmu_counters_test.c b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> index 8aaaf25b6111..cfeed0103341 100644
> --- a/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> +++ b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> @@ -311,7 +311,7 @@ static void guest_test_arch_events(void)
>  }
>  
>  static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
> -			     uint8_t length, uint8_t unavailable_mask)
> +			     uint8_t length, uint32_t unavailable_mask)
>  {
>  	struct kvm_vcpu *vcpu;
>  	struct kvm_vm *vm;
> @@ -320,6 +320,9 @@ static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
>  	if (!pmu_version)
>  		return;
>  
> +	unavailable_mask = GENMASK(X86_PROPERTY_PMU_EVENTS_MASK.hi_bit,
> +				   X86_PROPERTY_PMU_EVENTS_MASK.lo_bit);

Should be "unavailable_mask &="? Otherwise the incoming argument
"unavailable_mask" would be overwritten unconditionally. 


> +
>  	vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_test_arch_events,
>  					 pmu_version, perf_capabilities);
>  
> @@ -630,7 +633,7 @@ static void test_intel_counters(void)
>  			 */
>  			for (j = 0; j <= NR_INTEL_ARCH_EVENTS + 1; j++) {
>  				test_arch_events(v, perf_caps[i], j, 0);
> -				test_arch_events(v, perf_caps[i], j, 0xff);
> +				test_arch_events(v, perf_caps[i], j, -1u);
>  
>  				for (k = 0; k < NR_INTEL_ARCH_EVENTS; k++)
>  					test_arch_events(v, perf_caps[i], j, BIT(k));

On Fri, Sep 19, 2025, Dapeng Mi wrote:
> On 9/19/2025 8:45 AM, Sean Christopherson wrote:
> > diff --git a/tools/testing/selftests/kvm/x86/pmu_counters_test.c b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> > index 8aaaf25b6111..cfeed0103341 100644
> > --- a/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> > +++ b/tools/testing/selftests/kvm/x86/pmu_counters_test.c
> > @@ -311,7 +311,7 @@ static void guest_test_arch_events(void)
> >  }
> >  
> >  static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
> > -			     uint8_t length, uint8_t unavailable_mask)
> > +			     uint8_t length, uint32_t unavailable_mask)
> >  {
> >  	struct kvm_vcpu *vcpu;
> >  	struct kvm_vm *vm;
> > @@ -320,6 +320,9 @@ static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
> >  	if (!pmu_version)
> >  		return;
> >  
> > +	unavailable_mask = GENMASK(X86_PROPERTY_PMU_EVENTS_MASK.hi_bit,
> > +				   X86_PROPERTY_PMU_EVENTS_MASK.lo_bit);
> 
> Should be "unavailable_mask &="? Otherwise the incoming argument
> "unavailable_mask" would be overwritten unconditionally. 

/facepalm

Yes, definitely supposed to be &=.