Hi Jing,
On Tue, Apr 04, 2023 at 03:53:42AM +0000, Jing Zhang wrote:
> With per guest ID registers, PMUver settings from userspace
> can be stored in its corresponding ID register.
>
> No functional change intended.
>
> Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 11 +++----
> arch/arm64/kvm/arm.c | 6 ----
> arch/arm64/kvm/id_regs.c | 50 ++++++++++++++++++++++++-------
> include/kvm/arm_pmu.h | 5 ++--
> 4 files changed, 49 insertions(+), 23 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 67a55177fd83..da46a2729581 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -237,6 +237,12 @@ struct kvm_arch {
> #define KVM_ARCH_FLAG_EL1_32BIT 4
> /* PSCI SYSTEM_SUSPEND enabled for the guest */
> #define KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED 5
> + /*
> + * AA64DFR0_EL1.PMUver was set as ID_AA64DFR0_EL1_PMUVer_IMP_DEF
> + * or DFR0_EL1.PerfMon was set as ID_DFR0_EL1_PerfMon_IMPDEF from
> + * userspace for VCPUs without PMU.
> + */
> +#define KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU 6
>
> unsigned long flags;
>
> @@ -249,11 +255,6 @@ struct kvm_arch {
>
> cpumask_var_t supported_cpus;
>
> - struct {
> - u8 imp:4;
> - u8 unimp:4;
> - } dfr0_pmuver;
> -
> /* Hypercall features firmware registers' descriptor */
> struct kvm_smccc_features smccc_feat;
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 64e1c19e5a9b..3fe28d545b54 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -138,12 +138,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> kvm_arm_init_hypercalls(kvm);
> kvm_arm_init_id_regs(kvm);
>
> - /*
> - * Initialise the default PMUver before there is a chance to
> - * create an actual PMU.
> - */
> - kvm->arch.dfr0_pmuver.imp = kvm_arm_pmu_get_pmuver_limit();
> -
> return 0;
>
> err_free_cpumask:
> diff --git a/arch/arm64/kvm/id_regs.c b/arch/arm64/kvm/id_regs.c
> index 291311b1ecca..6f65d30693fe 100644
> --- a/arch/arm64/kvm/id_regs.c
> +++ b/arch/arm64/kvm/id_regs.c
> @@ -21,9 +21,12 @@
> static u8 vcpu_pmuver(const struct kvm_vcpu *vcpu)
> {
> if (kvm_vcpu_has_pmu(vcpu))
> - return vcpu->kvm->arch.dfr0_pmuver.imp;
> + return FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1));
> + else if (test_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags))
> + return ID_AA64DFR0_EL1_PMUVer_IMP_DEF;
>
> - return vcpu->kvm->arch.dfr0_pmuver.unimp;
> + return 0;
> }
>
> static u8 perfmon_to_pmuver(u8 perfmon)
> @@ -254,10 +257,20 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
> if (val)
> return -EINVAL;
>
> - if (valid_pmu)
> - vcpu->kvm->arch.dfr0_pmuver.imp = pmuver;
> - else
> - vcpu->kvm->arch.dfr0_pmuver.unimp = pmuver;
> + if (valid_pmu) {
> + mutex_lock(&vcpu->kvm->arch.config_lock);
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
> + pmuver);
> +
> + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) &= ~ID_DFR0_EL1_PerfMon_MASK;
> + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK,
> + pmuver_to_perfmon(pmuver));
As those could be read without acquiring the lock, I don't think
we should expose the intermediate state of the register values.
> + mutex_unlock(&vcpu->kvm->arch.config_lock);
> + } else {
> + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
> + pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF);
> + }
>
> return 0;
> }
> @@ -294,10 +307,19 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
> if (val)
> return -EINVAL;
>
> - if (valid_pmu)
> - vcpu->kvm->arch.dfr0_pmuver.imp = perfmon_to_pmuver(perfmon);
> - else
> - vcpu->kvm->arch.dfr0_pmuver.unimp = perfmon_to_pmuver(perfmon);
> + if (valid_pmu) {
> + mutex_lock(&vcpu->kvm->arch.config_lock);
> + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) &= ~ID_DFR0_EL1_PerfMon_MASK;
> + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon);
> +
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
> + perfmon_to_pmuver(perfmon));
I have the same comment as set_id_aa64dfr0_el1().
Thank you,
Reiji
> + mutex_unlock(&vcpu->kvm->arch.config_lock);
> + } else {
> + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
> + perfmon == ID_DFR0_EL1_PerfMon_IMPDEF);
> + }
>
> return 0;
> }
> @@ -503,4 +525,12 @@ void kvm_arm_init_id_regs(struct kvm *kvm)
> }
>
> IDREG(kvm, SYS_ID_AA64PFR0_EL1) = val;
> +
> + /*
> + * Initialise the default PMUver before there is a chance to
> + * create an actual PMU.
> + */
> + IDREG(kvm, SYS_ID_AA64DFR0_EL1) &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> + IDREG(kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
> + kvm_arm_pmu_get_pmuver_limit());
> }
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 628775334d5e..856ac59b6821 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -92,8 +92,9 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
> /*
> * Evaluates as true when emulating PMUv3p5, and false otherwise.
> */
> -#define kvm_pmu_is_3p5(vcpu) \
> - (vcpu->kvm->arch.dfr0_pmuver.imp >= ID_AA64DFR0_EL1_PMUVer_V3P5)
> +#define kvm_pmu_is_3p5(vcpu) \
> + (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), \
> + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1)) >= ID_AA64DFR0_EL1_PMUVer_V3P5)
>
> u8 kvm_arm_pmu_get_pmuver_limit(void);
>
> --
> 2.40.0.348.gf938b09366-goog
>
