[PATCH v10 3/5] KVM: arm64: Use per guest ID register for ID_AA64DFR0_EL1.PMUVer
Jing Zhang
jingzhangos at google.com
Tue May 30 11:35:39 PDT 2023
On Sun, May 28, 2023 at 3:53 AM Marc Zyngier <maz at kernel.org> wrote:
>
> On Mon, 22 May 2023 23:18:33 +0100,
> Jing Zhang <jingzhangos at google.com> 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 at google.com>
> > ---
> > arch/arm64/include/asm/kvm_host.h | 12 ++--
> > arch/arm64/kvm/arm.c | 6 --
> > arch/arm64/kvm/sys_regs.c | 100 ++++++++++++++++++++++++------
> > include/kvm/arm_pmu.h | 5 +-
> > 4 files changed, 92 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > index 8a2fde6c04c4..7b0f43373dbe 100644
> > --- a/arch/arm64/include/asm/kvm_host.h
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -246,6 +246,13 @@ struct kvm_arch {
> > #define KVM_ARCH_FLAG_TIMER_PPIS_IMMUTABLE 7
> > /* SMCCC filter initialized for the VM */
> > #define KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED 8
> > + /*
> > + * 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 9
> > +
> > unsigned long flags;
> >
> > /*
> > @@ -257,11 +264,6 @@ 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;
> > struct maple_tree smccc_filter;
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 5114521ace60..ca18c09ccf82 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -148,12 +148,6 @@ 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/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index 9fb1c2f8f5a5..84d9e4baa4f8 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -1178,9 +1178,12 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
> > 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)
> > @@ -1403,8 +1406,12 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
> > const struct sys_reg_desc *rd,
> > u64 val)
> > {
> > + struct kvm_arch *arch = &vcpu->kvm->arch;
> > + u64 old_val = read_id_reg(vcpu, rd);
> > u8 pmuver, host_pmuver;
> > + u64 new_val = val;
> > bool valid_pmu;
> > + int ret = 0;
> >
> > host_pmuver = kvm_arm_pmu_get_pmuver_limit();
> >
> > @@ -1424,26 +1431,51 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
> > if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
> > return -EINVAL;
> >
> > + mutex_lock(&arch->config_lock);
> > /* We can only differ with PMUver, and anything else is an error */
> > - val ^= read_id_reg(vcpu, rd);
> > + val ^= old_val;
> > val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> > - if (val)
> > - return -EINVAL;
> > + if (val) {
> > + ret = -EINVAL;
> > + goto out;
> > + }
> >
> > - if (valid_pmu)
> > - vcpu->kvm->arch.dfr0_pmuver.imp = pmuver;
> > - else
> > - vcpu->kvm->arch.dfr0_pmuver.unimp = pmuver;
> > + /* Only allow userspace to change the idregs before VM running */
> > + if (kvm_vm_has_ran_once(vcpu->kvm)) {
> > + if (new_val != old_val)
> > + ret = -EBUSY;
> > + } else {
> > + if (valid_pmu) {
> > + val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);
> > + val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
> > + val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, pmuver);
> > + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val;
> > +
> > + val = IDREG(vcpu->kvm, SYS_ID_DFR0_EL1);
> > + val &= ~ID_DFR0_EL1_PerfMon_MASK;
> > + val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, pmuver_to_perfmon(pmuver));
> > + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val;
> > + } else {
> > + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
> > + pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF);
> > + }
> > + }
> >
> > - return 0;
> > +out:
> > + mutex_unlock(&arch->config_lock);
> > + return ret;
> > }
> >
> > static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
> > const struct sys_reg_desc *rd,
> > u64 val)
> > {
> > + struct kvm_arch *arch = &vcpu->kvm->arch;
> > + u64 old_val = read_id_reg(vcpu, rd);
> > u8 perfmon, host_perfmon;
> > + u64 new_val = val;
> > bool valid_pmu;
> > + int ret = 0;
> >
> > host_perfmon = pmuver_to_perfmon(kvm_arm_pmu_get_pmuver_limit());
> >
> > @@ -1464,18 +1496,39 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
> > if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
> > return -EINVAL;
> >
> > + mutex_lock(&arch->config_lock);
> > /* We can only differ with PerfMon, and anything else is an error */
> > - val ^= read_id_reg(vcpu, rd);
> > + val ^= old_val;
> > val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
> > - if (val)
> > - return -EINVAL;
> > + if (val) {
> > + ret = -EINVAL;
> > + goto out;
> > + }
> >
> > - if (valid_pmu)
> > - vcpu->kvm->arch.dfr0_pmuver.imp = perfmon_to_pmuver(perfmon);
> > - else
> > - vcpu->kvm->arch.dfr0_pmuver.unimp = perfmon_to_pmuver(perfmon);
> > + /* Only allow userspace to change the idregs before VM running */
> > + if (kvm_vm_has_ran_once(vcpu->kvm)) {
> > + if (new_val != old_val)
> > + ret = -EBUSY;
> > + } else {
> > + if (valid_pmu) {
> > + val = IDREG(vcpu->kvm, SYS_ID_DFR0_EL1);
> > + val &= ~ID_DFR0_EL1_PerfMon_MASK;
> > + val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon);
> > + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val;
> > +
> > + val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);
> > + val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
> > + val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, perfmon_to_pmuver(perfmon));
> > + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val;
> > + } else {
> > + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
> > + perfmon == ID_DFR0_EL1_PerfMon_IMPDEF);
> > + }
> > + }
>
> This is the exact same code as for aa64fdr0. Make it a helper, please.
Will do.
>
> >
> > - return 0;
> > +out:
> > + mutex_unlock(&arch->config_lock);
> > + return ret;
> > }
> >
> > /*
> > @@ -3422,6 +3475,17 @@ 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.
> > + */
> > + val = IDREG(kvm, SYS_ID_AA64DFR0_EL1);
> > +
> > + val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> > + val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
> > + kvm_arm_pmu_get_pmuver_limit());
> > +
> > + IDREG(kvm, SYS_ID_AA64DFR0_EL1) = val;
> > }
> >
> > int __init kvm_sys_reg_table_init(void)
> > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> > index 1a6a695ca67a..8d70dbdc1e0a 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)
>
> This is getting unreadable. How about something like:
>
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 8d70dbdc1e0a..ecb55d87fa36 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -92,9 +92,13 @@ 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) \
> - (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), \
> - IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1)) >= ID_AA64DFR0_EL1_PMUVer_V3P5)
> +#define kvm_pmu_is_3p5(vcpu) ({ \
> + u64 val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1); \
> + u8 v; \
> + \
> + v = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), val); \
> + v >= ID_AA64DFR0_EL1_PMUVer_V3P5; \
> +})
>
> u8 kvm_arm_pmu_get_pmuver_limit(void);
Sure, will use your suggestion.
>
> Thanks,
>
> M.
>
> --
> Without deviation from the norm, progress is not possible.
Thanks,
Jing
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