[PATCH v3 12/22] KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned

Colton Lewis
2025-06-26T20:06:04Z

Because PMXEVTYPER is trapped and PMSELR is not, it is not appropriate
to use the virtual PMSELR register when it could be outdated and lead
to an invalid write. Use the physical register.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
arch/arm64/include/asm/arm_pmuv3.h | 7 ++++++-
arch/arm64/kvm/sys_regs.c | 9 +++++++--
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/arm_pmuv3.h b/arch/arm64/include/asm/arm_pmuv3.h
index e2057365ba73..1880e426a559 100644
--- a/arch/arm64/include/asm/arm_pmuv3.h
+++ b/arch/arm64/include/asm/arm_pmuv3.h
@@ -72,11 +72,16 @@ static inline u64 read_pmcr(void)
return read_sysreg(pmcr_el0);
}

-static inline void write_pmselr(u32 val)
+static inline void write_pmselr(u64 val)
{
write_sysreg(val, pmselr_el0);
}

+static inline u64 read_pmselr(void)
+{
+ return read_sysreg(pmselr_el0);
+}
+
static inline void write_pmccntr(u64 val)
{
write_sysreg(val, pmccntr_el0);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 49e8e3dcd306..771d73451b9a 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1065,14 +1065,19 @@ static bool writethrough_pmevtyper(struct kvm_vcpu *vcpu, struct sys_reg_params
static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
- u64 idx, reg;
+ u64 idx, reg, pmselr;

if (pmu_access_el0_disabled(vcpu))
return false;

if (r->CRn == 9 && r->CRm == 13 && r->Op2 == 1) {
/* PMXEVTYPER_EL0 */
- idx = SYS_FIELD_GET(PMSELR_EL0, SEL, __vcpu_sys_reg(vcpu, PMSELR_EL0));
+ if (kvm_vcpu_pmu_is_partitioned(vcpu))
+ pmselr = read_pmselr();
+ else
+ pmselr = __vcpu_sys_reg(vcpu, PMSELR_EL0);
+
+ idx = SYS_FIELD_GET(PMSELR_EL0, SEL, pmselr);
reg = PMEVTYPER0_EL0 + idx;
} else if (r->CRn == 14 && (r->CRm & 12) == 12) {
idx = ((r->CRm & 3) << 3) | (r->Op2 & 7);
--
2.50.0.727.gbf7dc18ff4-goog