[PATCH v3 13/22] KVM: arm64: Writethrough trapped PMOVS register

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

With FGT in place, the remaining trapped registers need to be written
through to the underlying physical registers as well as the virtual
ones. Failing to do this means delaying when guest writes take effect.

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 1880e426a559..3bddde5f4ebb 100644
--- a/arch/arm64/include/asm/arm_pmuv3.h
+++ b/arch/arm64/include/asm/arm_pmuv3.h
@@ -142,6 +142,16 @@ 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 771d73451b9a..cfbce4537b4c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1173,6 +1173,19 @@ 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)
{
@@ -1181,7 +1194,9 @@ 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));
--
2.50.0.727.gbf7dc18ff4-goog