[PATCH v5 13/24] KVM: arm64: Writethrough trapped PMOVS register

Colton Lewis
2025-12-09T20:52:41Z

Because PMOVS remains trapped, it needs to be written through when
partitioned to affect PMU hardware when expected.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
arch/arm64/include/asm/arm_pmuv3.h | 10 ++++++++++
arch/arm64/kvm/sys_regs.c | 17 ++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/arm_pmuv3.h b/arch/arm64/include/asm/arm_pmuv3.h
index 60600f04b5902..3e25c0313263c 100644
--- a/arch/arm64/include/asm/arm_pmuv3.h
+++ b/arch/arm64/include/asm/arm_pmuv3.h
@@ -140,6 +140,16 @@ static inline u64 read_pmicfiltr(void)
return read_sysreg_s(SYS_PMICFILTR_EL0);
}

+static inline void write_pmovsset(u64 val)
+{
+ write_sysreg(val, pmovsset_el0);
+}
+
+static inline u64 read_pmovsset(void)
+{
+ return read_sysreg(pmovsset_el0);
+}
+
static inline void write_pmovsclr(u64 val)
{
write_sysreg(val, pmovsclr_el0);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 2e6d907fa8af2..bee892db9ca8b 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1307,6 +1307,19 @@ static bool access_pminten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
return true;
}

+static void writethrough_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p, bool set)
+{
+ u64 mask = kvm_pmu_accessible_counter_mask(vcpu);
+
+ if (set) {
+ __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, (p->regval & mask));
+ write_pmovsset(p->regval & mask);
+ } else {
+ __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, &=, ~(p->regval & mask));
+ write_pmovsclr(p->regval & mask);
+ }
+}
+
static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
@@ -1315,7 +1328,9 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (pmu_access_el0_disabled(vcpu))
return false;

- if (p->is_write) {
+ if (kvm_vcpu_pmu_is_partitioned(vcpu) && p->is_write) {
+ writethrough_pmovs(vcpu, p, r->CRm & 0x2);
+ } else if (p->is_write) {
if (r->CRm & 0x2)
/* accessing PMOVSSET_EL0 */
__vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, (p->regval & mask));
--
2.52.0.239.gd5f0c6e74e-goog