Re: [PATCH v7 05/12] KVM: arm64: PMU: Add a helper to read a vCPU's PMCR_EL0

From: Eric Auger
Date: Mon Oct 16 2023 - 16:03:31 EST

Raghavendra,

On 10/10/23 01:08, Raghavendra Rao Ananta wrote:
> From: Reiji Watanabe <reijiw@xxxxxxxxxx>
>
> Add a helper to read a vCPU's PMCR_EL0, and use it when KVM
> reads a vCPU's PMCR_EL0.
>
> The PMCR_EL0 value is tracked by a sysreg file per each vCPU.
file?
> 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.
>
> Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
Besides
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>

Eric
> ---
> arch/arm64/kvm/arm.c | 3 +--
> arch/arm64/kvm/pmu-emul.c | 21 +++++++++++++++------
> arch/arm64/kvm/sys_regs.c | 6 +++---
> include/kvm/arm_pmu.h | 6 ++++++
> 4 files changed, 25 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 708a53b70a7b..0af4d6bbe3d3 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -854,8 +854,7 @@ 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);
> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
> index cc30c246c010..a161d6266a5c 100644
> --- a/arch/arm64/kvm/pmu-emul.c
> +++ b/arch/arm64/kvm/pmu-emul.c
> @@ -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));
> @@ -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)
> @@ -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++) {
> @@ -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);
> @@ -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 */
> @@ -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));
> }
>
> @@ -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);
> +}
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 08af7824e9d8..ff0f7095eaca 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -803,7 +803,7 @@ 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())
> @@ -811,7 +811,7 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> 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;
> }
> @@ -860,7 +860,7 @@ 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);
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 858ed9ce828a..cd980d78b86b 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -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 {
> };
> @@ -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