Hi Raghu,
On Mon, Oct 09, 2023 at 11:08:48PM +0000, Raghavendra Rao Ananta wrote:
> From: Reiji Watanabe <reijiw@xxxxxxxxxx>
>
> The following patches will use the number of counters information
> from the arm_pmu and use this to set the PMCR.N for the guest
> during vCPU reset. However, since the guest is not associated
> with any arm_pmu until userspace configures the vPMU device
> attributes, and a reset can happen before this event, assign a
> default PMU to the guest just before doing the reset.
>
> Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
> arch/arm64/kvm/arm.c | 20 ++++++++++++++++++++
> arch/arm64/kvm/pmu-emul.c | 12 ++----------
> include/kvm/arm_pmu.h | 6 ++++++
> 3 files changed, 28 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 78b0970eb8e6..708a53b70a7b 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1313,6 +1313,23 @@ static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu,
> KVM_VCPU_MAX_FEATURES);
> }
>
> +static int kvm_vcpu_set_pmu(struct kvm_vcpu *vcpu)
> +{
> + struct kvm *kvm = vcpu->kvm;
> +
> + if (!kvm_arm_support_pmu_v3())
> + return -EINVAL;
This check is pointless; the vCPU feature flags have been sanitised at
this point, and a requirement of having PMUv3 is that this predicate is
true.
> + /*
> + * When the vCPU has a PMU, but no PMU is set for the guest
> + * yet, set the default one.
> + */
> + if (unlikely(!kvm->arch.arm_pmu))
> + return kvm_arm_set_default_pmu(kvm);
> +
> + return 0;
> +}
> +
Apologies, I believe I was unclear last time around as to what I was
wanting here. Let's call this thing kvm_setup_vcpu() such that we can
add other one-time setup activities to it in the future.
Something like:
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 96641e442039..4896a44108e0 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1265,19 +1265,17 @@ static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu,
KVM_VCPU_MAX_FEATURES);
}
-static int kvm_vcpu_set_pmu(struct kvm_vcpu *vcpu)
+static int kvm_setup_vcpu(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
- if (!kvm_arm_support_pmu_v3())
- return -EINVAL;
-
/*
* When the vCPU has a PMU, but no PMU is set for the guest
* yet, set the default one.
*/
- if (unlikely(!kvm->arch.arm_pmu))
- return kvm_arm_set_default_pmu(kvm);
+ if (kvm_vcpu_has_pmu(vcpu) && !kvm->arch.arm_pmu &&
+ kvm_arm_set_default_pmu(kvm))
+ return -EINVAL;
return 0;
}
@@ -1297,7 +1295,8 @@ static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
bitmap_copy(kvm->arch.vcpu_features, &features, KVM_VCPU_MAX_FEATURES);
- if (kvm_vcpu_has_pmu(vcpu) && kvm_vcpu_set_pmu(vcpu))
+ ret = kvm_setup_vcpu(vcpu);
+ if (ret)
goto out_unlock;
/* Now we know what it is, we can reset it. */
--
Thanks,
Oliver
