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KVM: arm64: PMU: Add a helper to read a vCPU's PMCR_EL0
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Add a helper to read a vCPU's PMCR_EL0, and use it whenever KVM
reads a vCPU's PMCR_EL0.

Currently, the PMCR_EL0 value is tracked per vCPU. The following
patches will make (only) PMCR_EL0.N track per guest. Having the
new helper will be useful to combine the PMCR_EL0.N field
(tracked per guest) and the other fields (tracked per vCPU)
to provide the value of PMCR_EL0.

No functional change intended.

Reviewed-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231020214053.2144305-4-rananta@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Reiji Watanabe authored and Oliver Upton committed Oct 24, 2023
1 parent 4277335 commit 57fc267
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Showing 4 changed files with 25 additions and 11 deletions.
3 changes: 1 addition & 2 deletions arch/arm64/kvm/arm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -801,8 +801,7 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
}

if (kvm_check_request(KVM_REQ_RELOAD_PMU, vcpu))
kvm_pmu_handle_pmcr(vcpu,
__vcpu_sys_reg(vcpu, PMCR_EL0));
kvm_pmu_handle_pmcr(vcpu, kvm_vcpu_read_pmcr(vcpu));

if (kvm_check_request(KVM_REQ_RESYNC_PMU_EL0, vcpu))
kvm_vcpu_pmu_restore_guest(vcpu);
Expand Down
21 changes: 15 additions & 6 deletions arch/arm64/kvm/pmu-emul.c
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,7 @@ static bool kvm_pmc_is_64bit(struct kvm_pmc *pmc)

static bool kvm_pmc_has_64bit_overflow(struct kvm_pmc *pmc)
{
u64 val = __vcpu_sys_reg(kvm_pmc_to_vcpu(pmc), PMCR_EL0);
u64 val = kvm_vcpu_read_pmcr(kvm_pmc_to_vcpu(pmc));

return (pmc->idx < ARMV8_PMU_CYCLE_IDX && (val & ARMV8_PMU_PMCR_LP)) ||
(pmc->idx == ARMV8_PMU_CYCLE_IDX && (val & ARMV8_PMU_PMCR_LC));
Expand Down Expand Up @@ -250,7 +250,7 @@ void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu)

u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
{
u64 val = __vcpu_sys_reg(vcpu, PMCR_EL0) >> ARMV8_PMU_PMCR_N_SHIFT;
u64 val = kvm_vcpu_read_pmcr(vcpu) >> ARMV8_PMU_PMCR_N_SHIFT;

val &= ARMV8_PMU_PMCR_N_MASK;
if (val == 0)
Expand All @@ -272,7 +272,7 @@ void kvm_pmu_enable_counter_mask(struct kvm_vcpu *vcpu, u64 val)
if (!kvm_vcpu_has_pmu(vcpu))
return;

if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E) || !val)
if (!(kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E) || !val)
return;

for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
Expand Down Expand Up @@ -324,7 +324,7 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
{
u64 reg = 0;

if ((__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E)) {
if ((kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E)) {
reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
Expand Down Expand Up @@ -426,7 +426,7 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu *vcpu,
{
int i;

if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
if (!(kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E))
return;

/* Weed out disabled counters */
Expand Down Expand Up @@ -569,7 +569,7 @@ void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val)
static bool kvm_pmu_counter_is_enabled(struct kvm_pmc *pmc)
{
struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
return (__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E) &&
return (kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E) &&
(__vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & BIT(pmc->idx));
}

Expand Down Expand Up @@ -1084,3 +1084,12 @@ u8 kvm_arm_pmu_get_pmuver_limit(void)
ID_AA64DFR0_EL1_PMUVer_V3P5);
return FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), tmp);
}

/**
* kvm_vcpu_read_pmcr - Read PMCR_EL0 register for the vCPU
* @vcpu: The vcpu pointer
*/
u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
{
return __vcpu_sys_reg(vcpu, PMCR_EL0);
}
6 changes: 3 additions & 3 deletions arch/arm64/kvm/sys_regs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -822,15 +822,15 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
* Only update writeable bits of PMCR (continuing into
* kvm_pmu_handle_pmcr() as well)
*/
val = __vcpu_sys_reg(vcpu, PMCR_EL0);
val = kvm_vcpu_read_pmcr(vcpu);
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);
} else {
/* PMCR.P & PMCR.C are RAZ */
val = __vcpu_sys_reg(vcpu, PMCR_EL0)
val = kvm_vcpu_read_pmcr(vcpu)
& ~(ARMV8_PMU_PMCR_P | ARMV8_PMU_PMCR_C);
p->regval = val;
}
Expand Down Expand Up @@ -879,7 +879,7 @@ static bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
{
u64 pmcr, val;

pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
pmcr = kvm_vcpu_read_pmcr(vcpu);
val = (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
if (idx >= val && idx != ARMV8_PMU_CYCLE_IDX) {
kvm_inject_undefined(vcpu);
Expand Down
6 changes: 6 additions & 0 deletions include/kvm/arm_pmu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,7 @@ void kvm_vcpu_pmu_resync_el0(void);
u8 kvm_arm_pmu_get_pmuver_limit(void);
int kvm_arm_set_default_pmu(struct kvm *kvm);

u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu);
#else
struct kvm_pmu {
};
Expand Down Expand Up @@ -180,6 +181,11 @@ static inline int kvm_arm_set_default_pmu(struct kvm *kvm)
return -ENODEV;
}

static inline u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
{
return 0;
}

#endif

#endif

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