Oliver Upton <[email protected]> writes:
On Tue, Dec 09, 2025 at 08:51:13PM +0000, Colton Lewis wrote:
Make sure reads and writes to PMCR_EL0 conform to additional
constraints imposed when the PMU is partitioned.
Signed-off-by: Colton Lewis <[email protected]>
---
arch/arm64/kvm/pmu.c | 2 +-
arch/arm64/kvm/sys_regs.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 1fd012f8ff4a9..48b39f096fa12 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -877,7 +877,7 @@ 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);
Why can't the value of vcpu->kvm->arch.nr_pmu_counters be trusted?
Similar to discussion on a previous patch, I need to move some
validation to the ioctl where it's set.
@@ -1360,7 +1360,7 @@ 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_pmu_hpmn(vcpu))
kvm->arch.nr_pmu_counters = new_n;
This is the legacy UAPI for setting the number of PMU counters by
writing to PMCR_EL0.N.
The 'partitioned' implementation should take a dependency on the
SET_NR_COUNTERS attribute and reject attempts to change the value of
PMCR_EL0.N. Just like nested.
Good! I hated making writes to PMCR_EL0.N work and only did it because
of selftests assuming it did.
Thanks,
Oliver
