[PATCH v9 10/22] KVM: arm64: Add Partitioned PMU register trap handlers
Colton Lewis
coltonlewis at google.com
Thu Sep 24 10:29:16 PDT 2026
We may want a partitioned PMU but not have FEAT_FGT to untrap the
specific registers that would normally be untrapped. Add handling for
those trapped register accesses that does the right thing if the PMU
is partitioned.
For PMOVSCLR_EL0, clear guest overflow bits in both virtual and physical
registers. For PMEVTYPER and PMCCFILTR, write to the virtual register;
subsequent patches enforce the event filter at vcpu_load() and on
trapped register writes.
Signed-off-by: Colton Lewis <coltonlewis at google.com>
---
arch/arm64/kvm/pmu-direct.c | 51 +++++++
arch/arm64/kvm/sys_regs.c | 277 +++++++++++++++++++++++++++++-------
include/kvm/arm_pmu.h | 7 +
3 files changed, 287 insertions(+), 48 deletions(-)
diff --git a/arch/arm64/kvm/pmu-direct.c b/arch/arm64/kvm/pmu-direct.c
index f224b97823ce5..5045051e91cd3 100644
--- a/arch/arm64/kvm/pmu-direct.c
+++ b/arch/arm64/kvm/pmu-direct.c
@@ -64,6 +64,57 @@ bool kvm_pmu_is_partitioned(struct kvm *kvm)
return kvm && test_bit(KVM_ARCH_FLAG_PARTITION_PMU_ENABLED, &kvm->arch.flags);
}
+/**
+ * kvm_pmu_direct_pmcr_write() - Handle guest writes to PMCR_EL0
+ * @vcpu: Pointer to vcpu struct
+ * @val: Value written to PMCR_EL0
+ *
+ * Write control bits to physical pmcr_el0 and reset guest-owned general
+ * event counters when PMCR_EL0.P is set.
+ */
+void kvm_pmu_direct_pmcr_write(struct kvm_vcpu *vcpu, u64 val)
+{
+ bool reset_p = val & ARMV8_PMU_PMCR_P;
+ unsigned long mask;
+ int i;
+
+ val &= ~ARMV8_PMU_PMCR_P;
+
+ write_sysreg(val, pmcr_el0);
+
+ if (reset_p) {
+ mask = kvm_pmu_implemented_counter_mask(vcpu) & ~BIT(ARMV8_PMU_CYCLE_IDX);
+
+ if (!vcpu_is_el2(vcpu))
+ mask &= ~kvm_pmu_hyp_counter_mask(vcpu);
+
+ for_each_set_bit(i, &mask, ARMV8_PMU_MAX_GENERAL_COUNTERS)
+ write_pmevcntrn(i, 0);
+ }
+}
+
+/**
+ * kvm_pmu_direct_pmcr_read() - Handle guest reads from PMCR_EL0
+ * @vcpu: Pointer to vcpu struct
+ *
+ * Read physical pmcr_el0 and replace PMCR_EL0.N with the number of
+ * event counters partitioned to the guest.
+ *
+ * Return: Filtered PMCR_EL0 value
+ */
+u64 kvm_pmu_direct_pmcr_read(struct kvm_vcpu *vcpu)
+{
+ u64 n = vcpu->kvm->arch.nr_pmu_counters;
+
+ if (vcpu_has_nv(vcpu) && !vcpu_is_el2(vcpu))
+ n = FIELD_GET(MDCR_EL2_HPMN, __vcpu_sys_reg(vcpu, MDCR_EL2));
+
+ return u64_replace_bits(
+ read_sysreg(pmcr_el0),
+ n,
+ ARMV8_PMU_PMCR_N);
+}
+
/**
* kvm_pmu_host_counter_mask() - Compute bitmask of host-reserved counters
*
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index f7f750b7a91c4..c8210a8b10389 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1092,9 +1092,204 @@ static u64 reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
return __vcpu_sys_reg(vcpu, r->reg);
}
+/**
+ * pmu_reg_write() - Register writes for Partitioned PMU
+ * @vcpu: Pointer to vcpu
+ * @reg: vcpu register
+ * @val: value to write
+ * @set: setting or clearing a mask
+ *
+ * Helper for sys_reg.c register accessor functions.
+ */
+static void pmu_reg_write(struct kvm_vcpu *vcpu, enum vcpu_sysreg reg, u64 val, bool set)
+{
+ unsigned long flags;
+ u64 mask;
+ int idx;
+
+ switch (reg) {
+ case PMCR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ kvm_pmu_direct_pmcr_write(vcpu, val);
+ else
+ kvm_pmu_handle_pmcr(vcpu, val);
+ break;
+ case PMSELR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ write_sysreg(val, pmselr_el0);
+ __vcpu_assign_sys_reg(vcpu, reg, val);
+ break;
+ case PMEVCNTR0_EL0 ... PMCCNTR_EL0:
+ idx = reg - PMEVCNTR0_EL0;
+
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ if (idx == ARMV8_PMU_CYCLE_IDX)
+ write_sysreg(val, pmccntr_el0);
+ else
+ write_pmevcntrn(idx, val);
+ } else {
+ kvm_pmu_set_counter_value(vcpu, idx, val);
+ }
+ break;
+ case PMEVTYPER0_EL0 ... PMCCFILTR_EL0:
+ idx = reg - PMEVTYPER0_EL0;
+
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ mask = kvm_pmu_evtyper_mask(vcpu->kvm);
+ __vcpu_assign_sys_reg(vcpu, reg, val & mask);
+ } else {
+ kvm_pmu_set_counter_event_type(vcpu, val, idx);
+ kvm_vcpu_pmu_restore_guest(vcpu);
+ }
+ break;
+ case PMCNTENSET_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ if (set)
+ write_sysreg(val, pmcntenset_el0);
+ else
+ write_sysreg(val, pmcntenclr_el0);
+ } else {
+ if (set)
+ /* accessing PMCNTENSET_EL0 */
+ __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, |=, val);
+ else
+ /* accessing PMINTENCLR_EL1 */
+ __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, &=, ~val);
+
+ kvm_pmu_reprogram_counter_mask(vcpu, val);
+ }
+ break;
+ case PMINTENSET_EL1:
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ if (set)
+ write_sysreg(val, pmintenset_el1);
+ else
+ write_sysreg(val, pmintenclr_el1);
+ } else {
+ if (set)
+ /* accessing PMINTENSET_EL1 */
+ __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, |=, val);
+ else
+ /* accessing PMINTENCLR_EL1 */
+ __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, &=, ~val);
+ }
+ break;
+ case PMOVSSET_EL0:
+ local_irq_save(flags);
+ if (set) {
+ /* accessing PMOVSSET_EL0 */
+ __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, val);
+ } else {
+ /* accessing PMOVSCLR_EL0 */
+ __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, &=, ~val);
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ write_sysreg(val & kvm_pmu_guest_counter_mask(),
+ pmovsclr_el0);
+ }
+ local_irq_restore(flags);
+ break;
+ case PMUSERENR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ write_sysreg(val, pmuserenr_el0);
+ __vcpu_assign_sys_reg(vcpu, reg, val);
+ break;
+ default:
+ WARN_ON(1);
+ break;
+ }
+
+}
+
+/**
+ * pmu_reg_read() - Register reads for Partitioned PMU
+ * @vcpu: Pointer to vcpu
+ * @reg: vcpu register
+ *
+ * Helper for sys_reg.c register accessor functions.
+ *
+ * Return: value read
+ */
+static u64 pmu_reg_read(struct kvm_vcpu *vcpu, enum vcpu_sysreg reg)
+{
+ unsigned long flags;
+ u64 val = 0;
+ int idx;
+
+ switch (reg) {
+ case PMCR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ val = kvm_pmu_direct_pmcr_read(vcpu);
+ else
+ val = kvm_vcpu_read_pmcr(vcpu);
+ break;
+ case PMSELR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ val = read_sysreg(pmselr_el0);
+ else
+ val = __vcpu_sys_reg(vcpu, reg);
+ break;
+ case PMEVCNTR0_EL0 ... PMCCNTR_EL0:
+ idx = reg - PMEVCNTR0_EL0;
+
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ if (idx == ARMV8_PMU_CYCLE_IDX)
+ val = read_sysreg(pmccntr_el0);
+ else
+ val = read_pmevcntrn(idx);
+ } else {
+ val = kvm_pmu_get_counter_value(vcpu, idx);
+ }
+ break;
+ case PMEVTYPER0_EL0 ... PMCCFILTR_EL0:
+ val = __vcpu_sys_reg(vcpu, reg);
+ break;
+ case PMCNTENSET_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ val = read_sysreg(pmcntenset_el0);
+ val &= kvm_pmu_guest_counter_mask();
+ } else {
+ val = __vcpu_sys_reg(vcpu, reg);
+ }
+ break;
+ case PMINTENSET_EL1:
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ val = read_sysreg(pmintenset_el1);
+ val &= kvm_pmu_guest_counter_mask();
+ } else {
+ val = __vcpu_sys_reg(vcpu, reg);
+ }
+ break;
+ case PMOVSSET_EL0:
+ local_irq_save(flags);
+ if (kvm_pmu_is_partitioned(vcpu->kvm)) {
+ u64 hw_ovf = read_sysreg(pmovsset_el0) &
+ kvm_pmu_guest_counter_mask();
+
+ if (hw_ovf) {
+ __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, hw_ovf);
+ write_sysreg(hw_ovf, pmovsclr_el0);
+ }
+ }
+ val = __vcpu_sys_reg(vcpu, reg);
+ local_irq_restore(flags);
+ break;
+ case PMUSERENR_EL0:
+ if (kvm_pmu_is_partitioned(vcpu->kvm))
+ val = read_sysreg(pmuserenr_el0);
+ else
+ val = __vcpu_sys_reg(vcpu, reg);
+ break;
+ default:
+ WARN_ON(1);
+ break;
+ }
+
+ return val;
+}
+
static bool check_pmu_access_disabled(struct kvm_vcpu *vcpu, u64 flags)
{
- u64 reg = __vcpu_sys_reg(vcpu, PMUSERENR_EL0);
+ u64 reg = pmu_reg_read(vcpu, PMUSERENR_EL0);
bool enabled = (reg & flags) || vcpu_mode_priv(vcpu);
if (!enabled)
@@ -1133,18 +1328,17 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (p->is_write) {
/*
- * Only update writeable bits of PMCR (continuing into
- * kvm_pmu_handle_pmcr() as well)
+ * Only update writeable bits of PMCR
*/
- val = kvm_vcpu_read_pmcr(vcpu);
+ val = pmu_reg_read(vcpu, PMCR_EL0);
val &= ~ARMV8_PMU_PMCR_MASK;
val |= p->regval & ARMV8_PMU_PMCR_MASK;
if (!kvm_supports_32bit_el0())
val |= ARMV8_PMU_PMCR_LC;
- kvm_pmu_handle_pmcr(vcpu, val);
+ pmu_reg_write(vcpu, PMCR_EL0, val, 0);
} else {
/* PMCR.P & PMCR.C are RAZ */
- val = kvm_vcpu_read_pmcr(vcpu)
+ val = pmu_reg_read(vcpu, PMCR_EL0)
& ~(ARMV8_PMU_PMCR_P | ARMV8_PMU_PMCR_C);
p->regval = val;
}
@@ -1159,10 +1353,10 @@ static bool access_pmselr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
return false;
if (p->is_write)
- __vcpu_assign_sys_reg(vcpu, PMSELR_EL0, p->regval);
+ pmu_reg_write(vcpu, PMSELR_EL0, p->regval, 0);
else
/* return PMSELR.SEL field */
- p->regval = __vcpu_sys_reg(vcpu, PMSELR_EL0)
+ p->regval = pmu_reg_read(vcpu, PMSELR_EL0)
& PMSELR_EL0_SEL_MASK;
return true;
@@ -1239,6 +1433,7 @@ static bool access_pmu_evcntr(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
+ enum vcpu_sysreg reg;
u64 idx = ~0UL;
if (r->CRn == 9 && r->CRm == 13) {
@@ -1248,7 +1443,7 @@ static bool access_pmu_evcntr(struct kvm_vcpu *vcpu,
return false;
idx = SYS_FIELD_GET(PMSELR_EL0, SEL,
- __vcpu_sys_reg(vcpu, PMSELR_EL0));
+ pmu_reg_read(vcpu, PMSELR_EL0));
} else if (r->Op2 == 0) {
/* PMCCNTR_EL0 */
if (pmu_access_cycle_counter_el0_disabled(vcpu))
@@ -1276,18 +1471,21 @@ static bool access_pmu_evcntr(struct kvm_vcpu *vcpu,
if (!pmu_counter_idx_valid(vcpu, idx))
return false;
+ reg = PMEVCNTR0_EL0 + idx;
+
if (p->is_write) {
if (pmu_access_el0_disabled(vcpu))
return false;
- kvm_pmu_set_counter_value(vcpu, idx, p->regval);
+ pmu_reg_write(vcpu, reg, p->regval, 0);
} else {
- p->regval = kvm_pmu_get_counter_value(vcpu, idx);
+ p->regval = pmu_reg_read(vcpu, reg);
}
return true;
}
+
static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
@@ -1298,7 +1496,7 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
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));
+ idx = SYS_FIELD_GET(PMSELR_EL0, SEL, pmu_reg_read(vcpu, PMSELR_EL0));
reg = PMEVTYPER0_EL0 + idx;
} else if (r->CRn == 14 && (r->CRm & 12) == 12) {
idx = ((r->CRm & 3) << 3) | (r->Op2 & 7);
@@ -1314,12 +1512,10 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (!pmu_counter_idx_valid(vcpu, idx))
return false;
- if (p->is_write) {
- kvm_pmu_set_counter_event_type(vcpu, p->regval, idx);
- kvm_vcpu_pmu_restore_guest(vcpu);
- } else {
- p->regval = __vcpu_sys_reg(vcpu, reg);
- }
+ if (p->is_write)
+ pmu_reg_write(vcpu, reg, p->regval, 0);
+ else
+ p->regval = pmu_reg_read(vcpu, reg);
return true;
}
@@ -1353,16 +1549,9 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
mask = kvm_pmu_accessible_counter_mask(vcpu);
if (p->is_write) {
val = p->regval & mask;
- if (r->Op2 & 0x1)
- /* accessing PMCNTENSET_EL0 */
- __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, |=, val);
- else
- /* accessing PMCNTENCLR_EL0 */
- __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, &=, ~val);
-
- kvm_pmu_reprogram_counter_mask(vcpu, val);
+ pmu_reg_write(vcpu, PMCNTENSET_EL0, val, r->Op2 & 0x1);
} else {
- p->regval = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
+ p->regval = pmu_reg_read(vcpu, PMCNTENSET_EL0);
}
return true;
@@ -1371,22 +1560,17 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
static bool access_pminten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
- u64 mask = kvm_pmu_accessible_counter_mask(vcpu);
+ u64 val, mask;
if (check_pmu_access_disabled(vcpu, 0))
return false;
+ mask = kvm_pmu_accessible_counter_mask(vcpu);
if (p->is_write) {
- u64 val = p->regval & mask;
-
- if (r->Op2 & 0x1)
- /* accessing PMINTENSET_EL1 */
- __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, |=, val);
- else
- /* accessing PMINTENCLR_EL1 */
- __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, &=, ~val);
+ val = p->regval & mask;
+ pmu_reg_write(vcpu, PMINTENSET_EL1, val, r->Op2 & 0x1);
} else {
- p->regval = __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
+ p->regval = pmu_reg_read(vcpu, PMINTENSET_EL1);
}
return true;
@@ -1453,20 +1637,18 @@ static int set_pmmir(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
- u64 mask = kvm_pmu_accessible_counter_mask(vcpu);
+ u64 val, mask;
if (pmu_access_el0_disabled(vcpu))
return false;
+ mask = kvm_pmu_accessible_counter_mask(vcpu);
+
if (p->is_write) {
- if (r->CRm & 0x2)
- /* accessing PMOVSSET_EL0 */
- __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, (p->regval & mask));
- else
- /* accessing PMOVSCLR_EL0 */
- __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, &=, ~(p->regval & mask));
+ val = p->regval & mask;
+ pmu_reg_write(vcpu, PMOVSSET_EL0, val, r->CRm & 0x2);
} else {
- p->regval = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
+ p->regval = pmu_reg_read(vcpu, PMOVSSET_EL0);
}
return true;
@@ -1495,10 +1677,9 @@ static bool access_pmuserenr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (!vcpu_mode_priv(vcpu))
return undef_access(vcpu, p, r);
- __vcpu_assign_sys_reg(vcpu, PMUSERENR_EL0,
- (p->regval & ARMV8_PMU_USERENR_MASK));
+ pmu_reg_write(vcpu, PMUSERENR_EL0, p->regval & ARMV8_PMU_USERENR_MASK, 0);
} else {
- p->regval = __vcpu_sys_reg(vcpu, PMUSERENR_EL0)
+ p->regval = pmu_reg_read(vcpu, PMUSERENR_EL0)
& ARMV8_PMU_USERENR_MASK;
}
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 45ed338ee7504..a24788243ac99 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -98,6 +98,8 @@ void kvm_vcpu_pmu_resync_el0(void);
bool has_kvm_pmu_partition_support(void);
void kvm_pmu_partition_enable(struct kvm *kvm, bool enable);
bool kvm_pmu_is_partitioned(struct kvm *kvm);
+void kvm_pmu_direct_pmcr_write(struct kvm_vcpu *vcpu, u64 val);
+u64 kvm_pmu_direct_pmcr_read(struct kvm_vcpu *vcpu);
u64 kvm_pmu_host_counter_mask(void);
u64 kvm_pmu_guest_counter_mask(void);
/*
@@ -143,6 +145,11 @@ static inline bool kvm_pmu_is_partitioned(struct kvm *kvm)
{
return false;
}
+static inline void kvm_pmu_direct_pmcr_write(struct kvm_vcpu *vcpu, u64 val) {}
+static inline u64 kvm_pmu_direct_pmcr_read(struct kvm_vcpu *vcpu)
+{
+ return 0;
+}
static inline void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu,
u64 select_idx, u64 val) {}
static inline void kvm_pmu_set_counter_value_user(struct kvm_vcpu *vcpu,
--
2.56.0.rc1.310.g51773c2048-goog
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