diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 2 | ||||
| -rw-r--r-- | arch/arm64/kvm/arm.c | 16 | ||||
| -rw-r--r-- | arch/arm64/kvm/sys_regs.c | 42 |
3 files changed, 56 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 781d029b8aa8..0cd9f0f75c13 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -118,6 +118,8 @@ struct kvm_arch { */ unsigned long *pmu_filter; unsigned int pmuver; + + u8 pfr0_csv2; }; struct kvm_vcpu_fault_info { diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a3b32df1afb0..a6e25a4b4dc5 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -102,6 +102,20 @@ static int kvm_arm_default_max_vcpus(void) return vgic_present ? kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; } +static void set_default_csv2(struct kvm *kvm) +{ + /* + * 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. + */ + if (arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED) + kvm->arch.pfr0_csv2 = 1; +} + /** * kvm_arch_init_vm - initializes a VM data structure * @kvm: pointer to the KVM struct @@ -127,6 +141,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) /* The maximum number of VCPUs is limited by the host's GIC model */ kvm->arch.max_vcpus = kvm_arm_default_max_vcpus(); + set_default_csv2(kvm); + return ret; out_free_stage2_pgd: kvm_free_stage2_pgd(&kvm->arch.mmu); diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 6d287eefd9f1..0aa86250e354 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1128,9 +1128,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, if (!vcpu_has_sve(vcpu)) val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); val &= ~(0xfUL << ID_AA64PFR0_AMU_SHIFT); - if (!(val & (0xfUL << ID_AA64PFR0_CSV2_SHIFT)) && - arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED) - val |= (1UL << ID_AA64PFR0_CSV2_SHIFT); + val &= ~(0xfUL << ID_AA64PFR0_CSV2_SHIFT); + val |= ((u64)vcpu->kvm->arch.pfr0_csv2 << ID_AA64PFR0_CSV2_SHIFT); } else if (id == SYS_ID_AA64PFR1_EL1) { val &= ~(0xfUL << ID_AA64PFR1_MTE_SHIFT); } else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { @@ -1213,6 +1212,40 @@ 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, + const struct kvm_one_reg *reg, void __user *uaddr) +{ + const u64 id = sys_reg_to_index(rd); + int err; + u64 val; + u8 csv2; + + err = reg_from_user(&val, uaddr, id); + if (err) + return err; + + /* + * 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). + */ + csv2 = cpuid_feature_extract_unsigned_field(val, ID_AA64PFR0_CSV2_SHIFT); + if (csv2 > 1 || + (csv2 && arm64_get_spectre_v2_state() != SPECTRE_UNAFFECTED)) + return -EINVAL; + + /* We can only differ with CSV2, and anything else is an error */ + val ^= read_id_reg(vcpu, rd, false); + val &= ~(0xFUL << ID_AA64PFR0_CSV2_SHIFT); + if (val) + return -EINVAL; + + vcpu->kvm->arch.pfr0_csv2 = csv2; + + return 0; +} + /* * cpufeature ID register user accessors * @@ -1472,7 +1505,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { /* AArch64 ID registers */ /* CRm=4 */ - ID_SANITISED(ID_AA64PFR0_EL1), + { SYS_DESC(SYS_ID_AA64PFR0_EL1), .access = access_id_reg, + .get_user = get_id_reg, .set_user = set_id_aa64pfr0_el1, }, ID_SANITISED(ID_AA64PFR1_EL1), ID_UNALLOCATED(4,2), ID_UNALLOCATED(4,3), |