2020-03-02 10:49:16

by Eric Auger

Subject: [PATCH v2] KVM: arm64: pmu: Don't increment SW_INCR if PMCR.E is unset

commit 3837407c1aa1 upstream.

The specification says PMSWINC increments PMEVCNTR<n>_EL1 by 1
if PMEVCNTR<n>_EL0 is enabled and configured to count SW_INCR.

For PMEVCNTR<n>_EL0 to be enabled, we need both PMCNTENSET to
be set for the corresponding event counter but we also need
the PMCR.E bit to be set.

Fixes: 7a0adc7064b8 ("arm64: KVM: Add access handler for PMSWINC register")
Signed-off-by: Eric Auger <[email protected]>
Cc: <[email protected]> # 4.9 and 4.14 only

---

This is a backport of 3837407c1aa1 ("KVM: arm64: pmu: Don't
increment SW_INCR if PMCR.E is unset") which did not apply on
4.9-stable and 4.14-stable trees. Compared to the original patch
__vcpu_sys_reg() is replaced by vcpu_sys_reg().

v1 -> v2:
- this patch also is candidate for 4.9-stable
---
virt/kvm/arm/pmu.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 69ccce308458..9a47b0cfb01d 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -299,6 +299,9 @@ void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
if (val == 0)
return;

+ if (!(vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
+ return;
+
enable = vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
if (!(val & BIT(i)))
--
2.20.1

2020-03-02 10:50:38

by Marc Zyngier

Subject: Re: [PATCH v2] KVM: arm64: pmu: Don't increment SW_INCR if PMCR.E is unset

On 2020-03-02 10:48, Eric Auger wrote:
> commit 3837407c1aa1 upstream.
>
> The specification says PMSWINC increments PMEVCNTR<n>_EL1 by 1
> if PMEVCNTR<n>_EL0 is enabled and configured to count SW_INCR.
>
> For PMEVCNTR<n>_EL0 to be enabled, we need both PMCNTENSET to
> be set for the corresponding event counter but we also need
> the PMCR.E bit to be set.
>
> Fixes: 7a0adc7064b8 ("arm64: KVM: Add access handler for PMSWINC
> register")
> Signed-off-by: Eric Auger <[email protected]>
> Cc: <[email protected]> # 4.9 and 4.14 only

Reviewed-by: Marc Zyngier <[email protected]>

>
> ---
>
> This is a backport of 3837407c1aa1 ("KVM: arm64: pmu: Don't
> increment SW_INCR if PMCR.E is unset") which did not apply on
> 4.9-stable and 4.14-stable trees. Compared to the original patch
> __vcpu_sys_reg() is replaced by vcpu_sys_reg().
>
> v1 -> v2:
> - this patch also is candidate for 4.9-stable
> ---
> virt/kvm/arm/pmu.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> index 69ccce308458..9a47b0cfb01d 100644
> --- a/virt/kvm/arm/pmu.c
> +++ b/virt/kvm/arm/pmu.c
> @@ -299,6 +299,9 @@ void kvm_pmu_software_increment(struct kvm_vcpu
> *vcpu, u64 val)
> if (val == 0)
> return;
>
> + if (!(vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
> + return;
> +
> enable = vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
> for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
> if (!(val & BIT(i)))

--
Jazz is not dead. It just smells funny...