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KVM: arm64: PMU: Set PMCR_EL0.N for vCPU based on the associated PMU

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The number of PMU event counters is indicated in PMCR_EL0.N.
For a vCPU with PMUv3 configured, the value is set to the same
value as the current PE on every vCPU reset.  Unless the vCPU is
pinned to PEs that has the PMU associated to the guest from the
initial vCPU reset, the value might be different from the PMU's
PMCR_EL0.N on heterogeneous PMU systems.

Fix this by setting the vCPU's PMCR_EL0.N to the PMU's PMCR_EL0.N
value. Track the PMCR_EL0.N per guest, as only one PMU can be set
for the guest (PMCR_EL0.N must be the same for all vCPUs of the
guest), and it is convenient for updating the value.

To achieve this, the patch introduces a helper,
kvm_arm_pmu_get_max_counters(), that reads the maximum number of
counters from the arm_pmu associated to the VM. Make the function
global as upcoming patches will be interested to know the value
while setting the PMCR.N of the guest from userspace.

KVM does not yet support userspace modifying PMCR_EL0.N.
The following patch will add support for that.

Reviewed-by: Sebastian Ott <sebott@redhat.com>
Co-developed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Link: https://lore.kernel.org/r/20231020214053.2144305-5-rananta@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Raghavendra Rao Ananta
2023-10-20 21:40:44 +00:00
committed by Oliver Upton
parent 57fc267f1b
commit 4d20debf9c
4 changed files with 43 additions and 15 deletions
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include/kvm/arm_pmu.h
+6
View File
@@ -102,6 +102,7 @@ void kvm_vcpu_pmu_resync_el0(void);
u8 kvm_arm_pmu_get_pmuver_limit(void);
int kvm_arm_set_default_pmu(struct kvm *kvm);
u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm);
u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu);
#else
@@ -181,6 +182,11 @@ static inline int kvm_arm_set_default_pmu(struct kvm *kvm)
return -ENODEV;
}
static inline u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)
{
return 0;
}
static inline u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
{
return 0;