[PATCH v11 11/21] KVM: arm64: PMU: Recreate events after userspace event writes
COOLING10d
From: Akihiko Odaki <hidden>
Date: 2026-09-20 11:16:15
Also in:
kvm, kvmarm, linux-arm-kernel, linux-hardening, linux-kselftest, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
KVM_SET_ONE_REG writes to PMEVTYPERn_EL0 and PMCCFILTR_EL0 use the
generic raw system register assignment. If a backing perf event already
exists, it keeps its old event selection and privilege filters.
Add a setter that preserves the raw userspace register value and
requests deferred event recreation. This rebuilds the event on the vCPU
thread without changing values returned by KVM_GET_ONE_REG or applying
guest-write masking.
Fixes: 9feb21ac57d5 ("arm64: KVM: Add access handler for event type register")
Closes: https://sashiko.dev/#/patchset/20260720-hybrid-v9-0-2b713ca1b5dc@rsg.ci.i.u-tokyo.ac.jp?part=6
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Akihiko Odaki <redacted>
---
arch/arm64/kvm/sys_regs.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 6786311e9b7d..5a44bd5530ff 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -1334,6 +1334,15 @@ static int set_pmreg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, u64 va return 0; } +static int set_pmu_evtyper(struct kvm_vcpu *vcpu, + const struct sys_reg_desc *r, u64 val) +{ + __vcpu_assign_sys_reg(vcpu, r->reg, val); + kvm_pmu_request_recreate(vcpu); + + return 0; +} + static int get_pmreg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, u64 *val) { u64 mask = kvm_pmu_implemented_counter_mask(vcpu);
@@ -1584,7 +1593,7 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, /* Macro to expand the PMEVTYPERn_EL0 register */ #define PMU_PMEVTYPER_EL0(n) \ { PMU_SYS_REG(PMEVTYPERn_EL0(n)), \ - .reset = reset_pmevtyper, \ + .reset = reset_pmevtyper, .set_user = set_pmu_evtyper, \ .access = access_pmu_evtyper, .reg = (PMEVTYPER0_EL0 + n), } /* Macro to expand the AMU counter and type registers*/
@@ -3833,7 +3842,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { * in 32bit mode. Here we choose to reset it as zero for consistency. */ { PMU_SYS_REG(PMCCFILTR_EL0), .access = access_pmu_evtyper, - .reset = reset_val, .reg = PMCCFILTR_EL0, .val = 0 }, + .reset = reset_val, .reg = PMCCFILTR_EL0, .val = 0, + .set_user = set_pmu_evtyper }, EL2_REG_VNCR(VPIDR_EL2, reset_unknown, 0), EL2_REG_VNCR(VMPIDR_EL2, reset_unknown, 0),
--
2.55.0