diff options
Diffstat (limited to 'arch/arm64/kvm/hypercalls.c')
| -rw-r--r-- | arch/arm64/kvm/hypercalls.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 0be974e2f1fc..ba7cd84c6668 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -121,8 +121,58 @@ static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id) } } +#define SMCCC_ARCH_RANGE_BEGIN ARM_SMCCC_VERSION_FUNC_ID +#define SMCCC_ARCH_RANGE_END \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + 0, ARM_SMCCC_FUNC_MASK) + +static void init_smccc_filter(struct kvm *kvm) +{ + int r; + + mt_init(&kvm->arch.smccc_filter); + + /* + * Prevent userspace from handling any SMCCC calls in the architecture + * range, avoiding the risk of misrepresenting Spectre mitigation status + * to the guest. + */ + r = mtree_insert_range(&kvm->arch.smccc_filter, + SMCCC_ARCH_RANGE_BEGIN, SMCCC_ARCH_RANGE_END, + xa_mk_value(KVM_SMCCC_FILTER_HANDLE), + GFP_KERNEL_ACCOUNT); + WARN_ON_ONCE(r); +} + +static u8 kvm_smccc_filter_get_action(struct kvm *kvm, u32 func_id) +{ + unsigned long idx = func_id; + void *val; + + if (!test_bit(KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED, &kvm->arch.flags)) + return KVM_SMCCC_FILTER_HANDLE; + + /* + * But where's the error handling, you say? + * + * mt_find() returns NULL if no entry was found, which just so happens + * to match KVM_SMCCC_FILTER_HANDLE. + */ + val = mt_find(&kvm->arch.smccc_filter, &idx, idx); + return xa_to_value(val); +} + static u8 kvm_smccc_get_action(struct kvm_vcpu *vcpu, u32 func_id) { + /* + * Intervening actions in the SMCCC filter take precedence over the + * pseudo-firmware register bitmaps. + */ + u8 action = kvm_smccc_filter_get_action(vcpu->kvm, func_id); + if (action != KVM_SMCCC_FILTER_HANDLE) + return action; + if (kvm_smccc_test_fw_bmap(vcpu, func_id) || kvm_smccc_default_allowed(func_id)) return KVM_SMCCC_FILTER_HANDLE; @@ -263,6 +313,13 @@ void kvm_arm_init_hypercalls(struct kvm *kvm) smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES; smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES; smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES; + + init_smccc_filter(kvm); +} + +void kvm_arm_teardown_hypercalls(struct kvm *kvm) +{ + mtree_destroy(&kvm->arch.smccc_filter); } int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu) |