From: Christoffer Dall <christoffer.d...@linaro.org> We can have discrepancies between the nested stage 2 page table and the shadow one in a couple of cases. For example, the guest hypervisor can mark a page writable but the host hypervisor maps the page read-only in the shadow page table, if using something like KSM on the host level. In this case, a write fault is handled directly by the host hypervisor. But we could also simply have a read-only page mapped read-only in both tables, in which case the host hypervisor cannot do anything else than telling the guest hypervisor about the fault.
Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org> Signed-off-by: Jintack Lim <jintack....@linaro.org> --- arch/arm/include/asm/kvm_mmu.h | 7 +++++++ arch/arm64/include/asm/kvm_mmu.h | 2 ++ arch/arm64/kvm/mmu-nested.c | 22 ++++++++++++++++++++++ virt/kvm/arm/mmu.c | 7 +++++++ 4 files changed, 38 insertions(+) diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index 6a22846..1c5b652 100644 --- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -237,6 +237,13 @@ static inline int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa, return 0; } +static inline int kvm_s2_handle_perm_fault(struct kvm_vcpu *vcpu, + phys_addr_t fault_ipa, + struct kvm_s2_trans *trans) +{ + return 0; +} + static inline void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu) { } static inline void kvm_nested_s2_free(struct kvm *kvm) { } static inline void kvm_nested_s2_wp(struct kvm *kvm) { } diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 425e4a2..239bb89 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -337,6 +337,8 @@ struct kvm_s2_trans { void update_nested_s2_mmu(struct kvm_vcpu *vcpu); int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa, struct kvm_s2_trans *result); +int kvm_s2_handle_perm_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, + struct kvm_s2_trans *trans); void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu); void kvm_nested_s2_free(struct kvm *kvm); void kvm_nested_s2_wp(struct kvm *kvm); diff --git a/arch/arm64/kvm/mmu-nested.c b/arch/arm64/kvm/mmu-nested.c index 75570cc..a440d7b 100644 --- a/arch/arm64/kvm/mmu-nested.c +++ b/arch/arm64/kvm/mmu-nested.c @@ -271,6 +271,28 @@ int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa, return walk_nested_s2_pgd(vcpu, gipa, &wi, result); } +/* + * Returns non-zero if permission fault is handled by injecting it to the next + * level hypervisor. + */ +int kvm_s2_handle_perm_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, + struct kvm_s2_trans *trans) +{ + unsigned long fault_status = kvm_vcpu_trap_get_fault_type(vcpu); + bool write_fault = kvm_is_write_fault(vcpu); + + if (fault_status != FSC_PERM) + return 0; + + if ((write_fault && !trans->writable) || + (!write_fault && !trans->readable)) { + trans->esr = esr_s2_fault(vcpu, trans->level, ESR_ELx_FSC_PERM); + return 1; + } + + return 0; +} + /* expects kvm->mmu_lock to be held */ void kvm_nested_s2_wp(struct kvm *kvm) { diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 74941ad..4fb7b3b 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -1591,6 +1591,13 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) if (ret) goto out_unlock; + nested_trans.esr = 0; + ret = kvm_s2_handle_perm_fault(vcpu, fault_ipa, &nested_trans); + if (nested_trans.esr) + kvm_inject_s2_fault(vcpu, nested_trans.esr); + if (ret) + goto out_unlock; + ipa = nested_trans.output; } -- 1.9.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm