[PATCH v4 15/23] KVM: arm64: Account for partitioning in PMCR_EL0 access
Colton Lewis
coltonlewis at google.com
Mon Jul 14 15:59:09 PDT 2025
For some reason unknown to me, KVM allows writes to PMCR_EL0.N even
though the architecture specifies that field as RO. Make sure these
accesses conform to additional constraints imposed when the PMU is
partitioned.
Signed-off-by: Colton Lewis <coltonlewis at google.com>
---
arch/arm64/kvm/pmu.c | 2 +-
arch/arm64/kvm/sys_regs.c | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 30244eb7bc9b..1e5f46c1346c 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -883,7 +883,7 @@ u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu)
u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
{
u64 pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
- u64 n = vcpu->kvm->arch.nr_pmu_counters;
+ u64 n = kvm_pmu_guest_num_counters(vcpu);
if (vcpu_has_nv(vcpu) && !vcpu_is_el2(vcpu))
n = FIELD_GET(MDCR_EL2_HPMN, __vcpu_sys_reg(vcpu, MDCR_EL2));
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index ad9c406734a5..e3d4ca167881 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1247,7 +1247,9 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
*/
if (!kvm_vm_has_ran_once(kvm) &&
!vcpu_has_nv(vcpu) &&
- new_n <= kvm_arm_pmu_get_max_counters(kvm))
+ new_n <= kvm_arm_pmu_get_max_counters(kvm) &&
+ (!kvm_vcpu_pmu_is_partitioned(vcpu) ||
+ new_n <= kvm_pmu_hpmn(vcpu)))
kvm->arch.nr_pmu_counters = new_n;
mutex_unlock(&kvm->arch.config_lock);
--
2.50.0.727.gbf7dc18ff4-goog
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