[v3] KVM: arm64: PMU: Fix SET_ONE_REG for vPMC regs

[PATCH v3 6/6] KVM: arm64: Reload PMCNTENSET_EL0

Posted by Akihiko Odaki 9 months, 1 week ago

Disable counters that are no longer included in PMCNTENSET_EL0. It is
not necessary to enable counters included in PMCNTENSET_EL0 because
kvm_pmu_handle_pmcr() does so if appropriate.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 arch/arm64/kvm/pmu-emul.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 2d19c6048091..b14655dda6db 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -831,6 +831,8 @@ void kvm_vcpu_reload_pmu(struct kvm_vcpu *vcpu)
 {
 	u64 mask = kvm_pmu_valid_counter_mask(vcpu);
 
+	kvm_pmu_disable_counter_mask(vcpu, ~__vcpu_sys_reg(vcpu, PMCNTENSET_EL0));
+
 	__vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= mask;
 	__vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= mask;
 	__vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= mask;

-- 
2.48.1

Re: [PATCH v3 6/6] KVM: arm64: Reload PMCNTENSET_EL0

Posted by Oliver Upton 9 months, 1 week ago

On Wed, Mar 12, 2025 at 08:56:00PM +0900, Akihiko Odaki wrote:
> Disable counters that are no longer included in PMCNTENSET_EL0. It is
> not necessary to enable counters included in PMCNTENSET_EL0 because
> kvm_pmu_handle_pmcr() does so if appropriate.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  arch/arm64/kvm/pmu-emul.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
> index 2d19c6048091..b14655dda6db 100644
> --- a/arch/arm64/kvm/pmu-emul.c
> +++ b/arch/arm64/kvm/pmu-emul.c
> @@ -831,6 +831,8 @@ void kvm_vcpu_reload_pmu(struct kvm_vcpu *vcpu)
>  {
>  	u64 mask = kvm_pmu_valid_counter_mask(vcpu);
>  
> +	kvm_pmu_disable_counter_mask(vcpu, ~__vcpu_sys_reg(vcpu, PMCNTENSET_EL0));
> +

Just so this function appears consistent, can we move this after the
point where the mask is applied?

There's no functional impact of course since PMCR_EL0.N can only be
changed before the VM is started, i.e. not possible to have running
counters >= N.

Thanks,
Oliver