[PATCH v11 5/5] KVM: arm64: Refactor writings for PMUVer/CSV2/CSV3
Jing Zhang
jingzhangos at google.com
Fri Jun 2 17:08:18 PDT 2023
Hi Suraj,
On Fri, Jun 2, 2023 at 3:28 PM Jitindar Singh, Suraj <surajjs at amazon.com> wrote:
>
> On Fri, 2023-06-02 at 10:15 -0700, Jing Zhang wrote:
> > Hi Suraj,
> >
> > Let's continue the problem here you raised in the v9.
> > For the SVE example, the problem would be gone by enabling the
> > writable for SVE field? Since we are going to enable the writable for
> > all ID regs one by one later.
> > The double checking for CSV[2|3] is gone in this series.
> >
> > Thanks,
> > Jing
>
> Hi Jing,
>
> Correct. We need to in theory set the writable bit for all the fields
> we're manipulating in kvm_arm_read_id_reg(). I think I also ran into
> issues with the GIC bits.
Let's see how people like to fix the issue, by applying your patch or
just enabling writable for those fields.
>
> I guess for per vcpu values this raises the question of what it means
> to set them at a VM level (although I doubt anyone is setting these
> heterogeneously in practise).
For now, per vcpu values are handled on the fly. The VM-scope idregs
would save the latest write from the userspace.
>
> Thanks
> - Suraj
>
Thanks,
Jing
> >
> > On Thu, Jun 1, 2023 at 5:51 PM Jing Zhang <jingzhangos at google.com>
> > wrote:
> > >
> > > Refactor writings for ID_AA64PFR0_EL1.[CSV2|CSV3],
> > > ID_AA64DFR0_EL1.PMUVer and ID_DFR0_ELF.PerfMon based on utilities
> > > specific to ID register.
> > >
> > > Signed-off-by: Jing Zhang <jingzhangos at google.com>
> > > ---
> > > arch/arm64/include/asm/cpufeature.h | 1 +
> > > arch/arm64/kernel/cpufeature.c | 2 +-
> > > arch/arm64/kvm/sys_regs.c | 291 +++++++++++++++++++-----
> > > ----
> > > 3 files changed, 203 insertions(+), 91 deletions(-)
> > >
> > > diff --git a/arch/arm64/include/asm/cpufeature.h
> > > b/arch/arm64/include/asm/cpufeature.h
> > > index 6bf013fb110d..dc769c2eb7a4 100644
> > > --- a/arch/arm64/include/asm/cpufeature.h
> > > +++ b/arch/arm64/include/asm/cpufeature.h
> > > @@ -915,6 +915,7 @@ static inline unsigned int get_vmid_bits(u64
> > > mmfr1)
> > > return 8;
> > > }
> > >
> > > +s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64
> > > new, s64 cur);
> > > struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id);
> > >
> > > extern struct arm64_ftr_override id_aa64mmfr1_override;
> > > diff --git a/arch/arm64/kernel/cpufeature.c
> > > b/arch/arm64/kernel/cpufeature.c
> > > index 7d7128c65161..3317a7b6deac 100644
> > > --- a/arch/arm64/kernel/cpufeature.c
> > > +++ b/arch/arm64/kernel/cpufeature.c
> > > @@ -798,7 +798,7 @@ static u64 arm64_ftr_set_value(const struct
> > > arm64_ftr_bits *ftrp, s64 reg,
> > > return reg;
> > > }
> > >
> > > -static s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp,
> > > s64 new,
> > > +s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64
> > > new,
> > > s64 cur)
> > > {
> > > s64 ret = 0;
> > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > > index 1a534e0fc4ca..50d4e25f42d3 100644
> > > --- a/arch/arm64/kvm/sys_regs.c
> > > +++ b/arch/arm64/kvm/sys_regs.c
> > > @@ -41,6 +41,7 @@
> > > * 64bit interface.
> > > */
> > >
> > > +static int set_id_reg(struct kvm_vcpu *vcpu, const struct
> > > sys_reg_desc *rd, u64 val);
> > > static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32
> > > encoding);
> > > static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
> > >
> > > @@ -1194,6 +1195,86 @@ static bool access_arch_timer(struct
> > > kvm_vcpu *vcpu,
> > > return true;
> > > }
> > >
> > > +static s64 kvm_arm64_ftr_safe_value(u32 id, const struct
> > > arm64_ftr_bits *ftrp,
> > > + s64 new, s64 cur)
> > > +{
> > > + struct arm64_ftr_bits kvm_ftr = *ftrp;
> > > +
> > > + /* Some features have different safe value type in KVM than
> > > host features */
> > > + switch (id) {
> > > + case SYS_ID_AA64DFR0_EL1:
> > > + if (kvm_ftr.shift == ID_AA64DFR0_EL1_PMUVer_SHIFT)
> > > + kvm_ftr.type = FTR_LOWER_SAFE;
> > > + break;
> > > + case SYS_ID_DFR0_EL1:
> > > + if (kvm_ftr.shift == ID_DFR0_EL1_PerfMon_SHIFT)
> > > + kvm_ftr.type = FTR_LOWER_SAFE;
> > > + break;
> > > + }
> > > +
> > > + return arm64_ftr_safe_value(&kvm_ftr, new, cur);
> > > +}
> > > +
> > > +/**
> > > + * arm64_check_features() - Check if a feature register value
> > > constitutes
> > > + * a subset of features indicated by the idreg's KVM sanitised
> > > limit.
> > > + *
> > > + * This function will check if each feature field of @val is the
> > > "safe" value
> > > + * against idreg's KVM sanitised limit return from reset()
> > > callback.
> > > + * If a field value in @val is the same as the one in limit, it is
> > > always
> > > + * considered the safe value regardless For register fields that
> > > are not in
> > > + * writable, only the value in limit is considered the safe value.
> > > + *
> > > + * Return: 0 if all the fields are safe. Otherwise, return
> > > negative errno.
> > > + */
> > > +static int arm64_check_features(struct kvm_vcpu *vcpu,
> > > + const struct sys_reg_desc *rd,
> > > + u64 val)
> > > +{
> > > + const struct arm64_ftr_reg *ftr_reg;
> > > + const struct arm64_ftr_bits *ftrp = NULL;
> > > + u32 id = reg_to_encoding(rd);
> > > + u64 writable_mask = rd->val;
> > > + u64 limit = 0;
> > > + u64 mask = 0;
> > > +
> > > + /* For hidden and unallocated idregs without reset, only
> > > val = 0 is allowed. */
> > > + if (rd->reset) {
> > > + limit = rd->reset(vcpu, rd);
> > > + ftr_reg = get_arm64_ftr_reg(id);
> > > + if (!ftr_reg)
> > > + return -EINVAL;
> > > + ftrp = ftr_reg->ftr_bits;
> > > + }
> > > +
> > > + for (; ftrp && ftrp->width; ftrp++) {
> > > + s64 f_val, f_lim, safe_val;
> > > + u64 ftr_mask;
> > > +
> > > + ftr_mask = arm64_ftr_mask(ftrp);
> > > + if ((ftr_mask & writable_mask) != ftr_mask)
> > > + continue;
> > > +
> > > + f_val = arm64_ftr_value(ftrp, val);
> > > + f_lim = arm64_ftr_value(ftrp, limit);
> > > + mask |= ftr_mask;
> > > +
> > > + if (f_val == f_lim)
> > > + safe_val = f_val;
> > > + else
> > > + safe_val = kvm_arm64_ftr_safe_value(id,
> > > ftrp, f_val, f_lim);
> > > +
> > > + if (safe_val != f_val)
> > > + return -E2BIG;
> > > + }
> > > +
> > > + /* For fields that are not writable, values in limit are
> > > the safe values. */
> > > + if ((val & ~mask) != (limit & ~mask))
> > > + return -E2BIG;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > static u8 vcpu_pmuver(const struct kvm_vcpu *vcpu)
> > > {
> > > if (kvm_vcpu_has_pmu(vcpu))
> > > @@ -1231,9 +1312,17 @@ static u8 pmuver_to_perfmon(u8 pmuver)
> > > }
> > > }
> > >
> > > -static void pmuver_update(struct kvm_vcpu *vcpu, u8 pmuver, bool
> > > valid_pmu)
> > > +static int pmuver_update(struct kvm_vcpu *vcpu,
> > > + const struct sys_reg_desc *rd,
> > > + u64 val,
> > > + u8 pmuver,
> > > + bool valid_pmu)
> > > {
> > > - u64 val;
> > > + int ret;
> > > +
> > > + ret = set_id_reg(vcpu, rd, val);
> > > + if (ret)
> > > + return ret;
> > >
> > > if (valid_pmu) {
> > > val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);
> > > @@ -1249,6 +1338,8 @@ static void pmuver_update(struct kvm_vcpu
> > > *vcpu, u8 pmuver, bool valid_pmu)
> > > assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU,
> > > &vcpu->kvm->arch.flags,
> > > pmuver ==
> > > ID_AA64DFR0_EL1_PMUVer_IMP_DEF);
> > > }
> > > +
> > > + return 0;
> > > }
> > >
> > > static u64 general_read_kvm_sanitised_reg(struct kvm_vcpu *vcpu,
> > > const struct sys_reg_desc *rd)
> > > @@ -1264,7 +1355,6 @@ static u64 kvm_arm_read_id_reg(const struct
> > > kvm_vcpu *vcpu, u32 encoding)
> > > case SYS_ID_AA64PFR0_EL1:
> > > if (!vcpu_has_sve(vcpu))
> > > val &=
> > > ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE);
> > > - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU);
> > > if (kvm_vgic_global_state.type == VGIC_V3) {
> > > val &=
> > > ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC);
> > > val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC), 1);
> > > @@ -1291,15 +1381,10 @@ static u64 kvm_arm_read_id_reg(const struct
> > > kvm_vcpu *vcpu, u32 encoding)
> > > val &=
> > > ~ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_WFxT);
> > > break;
> > > case SYS_ID_AA64DFR0_EL1:
> > > - /* Limit debug to ARMv8.0 */
> > > - val &=
> > > ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer);
> > > - val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer), 6);
> > > /* Set PMUver to the required version */
> > > val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> > > val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
> > > vcpu_pmuver(vcpu));
> > > - /* Hide SPE from guests */
> > > - val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMSVer);
> > > break;
> > > case SYS_ID_DFR0_EL1:
> > > val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
> > > @@ -1398,38 +1483,56 @@ static unsigned int sve_visibility(const
> > > struct kvm_vcpu *vcpu,
> > > return REG_HIDDEN;
> > > }
> > >
> > > -static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
> > > - const struct sys_reg_desc *rd,
> > > - u64 val)
> > > +static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
> > > + const struct sys_reg_desc
> > > *rd)
> > > {
> > > - u64 new_val = val;
> > > - u8 csv2, csv3;
> > > + u64 val;
> > > + u32 id = reg_to_encoding(rd);
> > >
> > > + val = read_sanitised_ftr_reg(id);
> > > /*
> > > - * Allow AA64PFR0_EL1.CSV2 to be set from userspace as long
> > > as
> > > - * it doesn't promise more than what is actually provided
> > > (the
> > > - * guest could otherwise be covered in ectoplasmic
> > > residue).
> > > + * The default is to expose CSV2 == 1 if the HW isn't
> > > affected.
> > > + * Although this is a per-CPU feature, we make it global
> > > because
> > > + * asymmetric systems are just a nuisance.
> > > + *
> > > + * Userspace can override this as long as it doesn't
> > > promise
> > > + * the impossible.
> > > */
> > > - csv2 = cpuid_feature_extract_unsigned_field(val,
> > > ID_AA64PFR0_EL1_CSV2_SHIFT);
> > > - if (csv2 > 1 ||
> > > - (csv2 && arm64_get_spectre_v2_state() !=
> > > SPECTRE_UNAFFECTED))
> > > - return -EINVAL;
> > > + if (arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED) {
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2);
> > > + val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2), 1);
> > > + }
> > > + if (arm64_get_meltdown_state() == SPECTRE_UNAFFECTED) {
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3);
> > > + val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3), 1);
> > > + }
> > >
> > > - /* Same thing for CSV3 */
> > > - csv3 = cpuid_feature_extract_unsigned_field(val,
> > > ID_AA64PFR0_EL1_CSV3_SHIFT);
> > > - if (csv3 > 1 ||
> > > - (csv3 && arm64_get_meltdown_state() !=
> > > SPECTRE_UNAFFECTED))
> > > - return -EINVAL;
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU);
> > >
> > > - /* We can only differ with CSV[23], and anything else is an
> > > error */
> > > - val ^= read_id_reg(vcpu, rd);
> > > - val &= ~(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2) |
> > > - ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3));
> > > - if (val)
> > > - return -EINVAL;
> > > + return val;
> > > +}
> > >
> > > - IDREG(vcpu->kvm, reg_to_encoding(rd)) = new_val;
> > > - return 0;
> > > +static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
> > > + const struct sys_reg_desc
> > > *rd)
> > > +{
> > > + u64 val;
> > > + u32 id = reg_to_encoding(rd);
> > > +
> > > + val = read_sanitised_ftr_reg(id);
> > > + /* Limit debug to ARMv8.0 */
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer);
> > > + val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer), 6);
> > > + /*
> > > + * Initialise the default PMUver before there is a chance
> > > to
> > > + * create an actual PMU.
> > > + */
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> > > + val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
> > > + kvm_arm_pmu_get_pmuver_limit());
> > > + /* Hide SPE from guests */
> > > + val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMSVer);
> > > +
> > > + return val;
> > > }
> > >
> > > static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
> > > @@ -1457,14 +1560,35 @@ static int set_id_aa64dfr0_el1(struct
> > > kvm_vcpu *vcpu,
> > > if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
> > > return -EINVAL;
> > >
> > > - /* We can only differ with PMUver, and anything else is an
> > > error */
> > > - val ^= read_id_reg(vcpu, rd);
> > > - val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
> > > - if (val)
> > > - return -EINVAL;
> > > + if (!valid_pmu) {
> > > + /*
> > > + * Ignore the PMUVer field in @val. The PMUVer
> > > would be determined
> > > + * by arch flags bit
> > > KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU,
> > > + */
> > > + pmuver = FIELD_GET(ID_AA64DFR0_EL1_PMUVer_MASK,
> > > + IDREG(vcpu->kvm,
> > > SYS_ID_AA64DFR0_EL1));
> > > + val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
> > > + val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
> > > pmuver);
> > > + }
> > >
> > > - pmuver_update(vcpu, pmuver, valid_pmu);
> > > - return 0;
> > > + return pmuver_update(vcpu, rd, val, pmuver, valid_pmu);
> > > +}
> > > +
> > > +static u64 read_sanitised_id_dfr0_el1(struct kvm_vcpu *vcpu,
> > > + const struct sys_reg_desc
> > > *rd)
> > > +{
> > > + u64 val;
> > > + u32 id = reg_to_encoding(rd);
> > > +
> > > + val = read_sanitised_ftr_reg(id);
> > > + /*
> > > + * Initialise the default PMUver before there is a chance
> > > to
> > > + * create an actual PMU.
> > > + */
> > > + val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
> > > + val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon),
> > > kvm_arm_pmu_get_pmuver_limit());
> > > +
> > > + return val;
> > > }
> > >
> > > static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
> > > @@ -1493,14 +1617,18 @@ static int set_id_dfr0_el1(struct kvm_vcpu
> > > *vcpu,
> > > if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
> > > return -EINVAL;
> > >
> > > - /* We can only differ with PerfMon, and anything else is an
> > > error */
> > > - val ^= read_id_reg(vcpu, rd);
> > > - val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
> > > - if (val)
> > > - return -EINVAL;
> > > + if (!valid_pmu) {
> > > + /*
> > > + * Ignore the PerfMon field in @val. The PerfMon
> > > would be determined
> > > + * by arch flags bit
> > > KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU,
> > > + */
> > > + perfmon = FIELD_GET(ID_DFR0_EL1_PerfMon_MASK,
> > > + IDREG(vcpu->kvm,
> > > SYS_ID_DFR0_EL1));
> > > + val &= ~ID_DFR0_EL1_PerfMon_MASK;
> > > + val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK,
> > > perfmon);
> > > + }
> > >
> > > - pmuver_update(vcpu, perfmon_to_pmuver(perfmon), valid_pmu);
> > > - return 0;
> > > + return pmuver_update(vcpu, rd, val,
> > > perfmon_to_pmuver(perfmon), valid_pmu);
> > > }
> > >
> > > /*
> > > @@ -1520,11 +1648,14 @@ static int get_id_reg(struct kvm_vcpu
> > > *vcpu, const struct sys_reg_desc *rd,
> > > static int set_id_reg(struct kvm_vcpu *vcpu, const struct
> > > sys_reg_desc *rd,
> > > u64 val)
> > > {
> > > - /* This is what we mean by invariant: you can't change it.
> > > */
> > > - if (val != read_id_reg(vcpu, rd))
> > > - return -EINVAL;
> > > + u32 id = reg_to_encoding(rd);
> > > + int ret = 0;
> > >
> > > - return 0;
> > > + ret = arm64_check_features(vcpu, rd, val);
> > > + if (!ret)
> > > + IDREG(vcpu->kvm, id) = val;
> > > +
> > > + return ret;
> > > }
> > >
> > > static int get_raz_reg(struct kvm_vcpu *vcpu, const struct
> > > sys_reg_desc *rd,
> > > @@ -1875,9 +2006,13 @@ static const struct sys_reg_desc
> > > sys_reg_descs[] = {
> > > /* CRm=1 */
> > > AA32_ID_SANITISED(ID_PFR0_EL1),
> > > AA32_ID_SANITISED(ID_PFR1_EL1),
> > > - { SYS_DESC(SYS_ID_DFR0_EL1), .access = access_id_reg,
> > > - .get_user = get_id_reg, .set_user = set_id_dfr0_el1,
> > > - .visibility = aa32_id_visibility, },
> > > + { SYS_DESC(SYS_ID_DFR0_EL1),
> > > + .access = access_id_reg,
> > > + .get_user = get_id_reg,
> > > + .set_user = set_id_dfr0_el1,
> > > + .visibility = aa32_id_visibility,
> > > + .reset = read_sanitised_id_dfr0_el1,
> > > + .val = ID_DFR0_EL1_PerfMon_MASK, },
> > > ID_HIDDEN(ID_AFR0_EL1),
> > > AA32_ID_SANITISED(ID_MMFR0_EL1),
> > > AA32_ID_SANITISED(ID_MMFR1_EL1),
> > > @@ -1906,8 +2041,12 @@ static const struct sys_reg_desc
> > > sys_reg_descs[] = {
> > >
> > > /* AArch64 ID registers */
> > > /* CRm=4 */
> > > - { SYS_DESC(SYS_ID_AA64PFR0_EL1), .access = access_id_reg,
> > > - .get_user = get_id_reg, .set_user = set_id_aa64pfr0_el1,
> > > },
> > > + { SYS_DESC(SYS_ID_AA64PFR0_EL1),
> > > + .access = access_id_reg,
> > > + .get_user = get_id_reg,
> > > + .set_user = set_id_reg,
> > > + .reset = read_sanitised_id_aa64pfr0_el1,
> > > + .val = ID_AA64PFR0_EL1_CSV2_MASK |
> > > ID_AA64PFR0_EL1_CSV3_MASK, },
> > > ID_SANITISED(ID_AA64PFR1_EL1),
> > > ID_UNALLOCATED(4,2),
> > > ID_UNALLOCATED(4,3),
> > > @@ -1917,8 +2056,12 @@ static const struct sys_reg_desc
> > > sys_reg_descs[] = {
> > > ID_UNALLOCATED(4,7),
> > >
> > > /* CRm=5 */
> > > - { SYS_DESC(SYS_ID_AA64DFR0_EL1), .access = access_id_reg,
> > > - .get_user = get_id_reg, .set_user = set_id_aa64dfr0_el1,
> > > },
> > > + { SYS_DESC(SYS_ID_AA64DFR0_EL1),
> > > + .access = access_id_reg,
> > > + .get_user = get_id_reg,
> > > + .set_user = set_id_aa64dfr0_el1,
> > > + .reset = read_sanitised_id_aa64dfr0_el1,
> > > + .val = ID_AA64DFR0_EL1_PMUVer_MASK, },
> > > ID_SANITISED(ID_AA64DFR1_EL1),
> > > ID_UNALLOCATED(5,2),
> > > ID_UNALLOCATED(5,3),
> > > @@ -3454,38 +3597,6 @@ void kvm_arm_init_id_regs(struct kvm *kvm)
> > > idreg++;
> > > id = reg_to_encoding(idreg);
> > > }
> > > -
> > > - /*
> > > - * The default is to expose CSV2 == 1 if the HW isn't
> > > affected.
> > > - * Although this is a per-CPU feature, we make it global
> > > because
> > > - * asymmetric systems are just a nuisance.
> > > - *
> > > - * Userspace can override this as long as it doesn't
> > > promise
> > > - * the impossible.
> > > - */
> > > - val = IDREG(kvm, SYS_ID_AA64PFR0_EL1);
> > > -
> > > - if (arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED) {
> > > - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2);
> > > - val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2), 1);
> > > - }
> > > - if (arm64_get_meltdown_state() == SPECTRE_UNAFFECTED) {
> > > - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3);
> > > - val |=
> > > FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3), 1);
> > > - }
> > > -
> > > - 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)
> > > --
> > > 2.41.0.rc0.172.g3f132b7071-goog
> > >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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