From 85ea6b1ec915c9dd90caf3674b203999d8c7e062 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 21 Apr 2022 15:38:10 +0100 Subject: [PATCH] KVM: arm64: Inject exception on out-of-IPA-range translation fault When taking a translation fault for an IPA that is outside of the range defined by the hypervisor (between the HW PARange and the IPA range), we stupidly treat it as an IO and forward the access to userspace. Of course, userspace can't do much with it, and things end badly. Arguably, the guest is braindead, but we should at least catch the case and inject an exception. Check the faulting IPA against: - the sanitised PARange: inject an address size fault - the IPA size: inject an abort Reported-by: Christoffer Dall Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_emulate.h | 1 + arch/arm64/kvm/inject_fault.c | 28 ++++++++++++++++++++++++++++ arch/arm64/kvm/mmu.c | 19 +++++++++++++++++++ 3 files changed, 48 insertions(+) diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 7496deab025a..f71358271b71 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -40,6 +40,7 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu); void kvm_inject_vabt(struct kvm_vcpu *vcpu); void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr); void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr); +void kvm_inject_size_fault(struct kvm_vcpu *vcpu); void kvm_vcpu_wfi(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c index b47df73e98d7..ba20405d2dc2 100644 --- a/arch/arm64/kvm/inject_fault.c +++ b/arch/arm64/kvm/inject_fault.c @@ -145,6 +145,34 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr) inject_abt64(vcpu, true, addr); } +void kvm_inject_size_fault(struct kvm_vcpu *vcpu) +{ + unsigned long addr, esr; + + addr = kvm_vcpu_get_fault_ipa(vcpu); + addr |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0); + + if (kvm_vcpu_trap_is_iabt(vcpu)) + kvm_inject_pabt(vcpu, addr); + else + kvm_inject_dabt(vcpu, addr); + + /* + * If AArch64 or LPAE, set FSC to 0 to indicate an Address + * Size Fault at level 0, as if exceeding PARange. + * + * Non-LPAE guests will only get the external abort, as there + * is no way to to describe the ASF. + */ + if (vcpu_el1_is_32bit(vcpu) && + !(vcpu_read_sys_reg(vcpu, TCR_EL1) & TTBCR_EAE)) + return; + + esr = vcpu_read_sys_reg(vcpu, ESR_EL1); + esr &= ~GENMASK_ULL(5, 0); + vcpu_write_sys_reg(vcpu, esr, ESR_EL1); +} + /** * kvm_inject_undefined - inject an undefined instruction into the guest * @vcpu: The vCPU in which to inject the exception diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 53ae2c0640bc..5400fc020164 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1337,6 +1337,25 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) fault_ipa = kvm_vcpu_get_fault_ipa(vcpu); is_iabt = kvm_vcpu_trap_is_iabt(vcpu); + if (fault_status == FSC_FAULT) { + /* Beyond sanitised PARange (which is the IPA limit) */ + if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) { + kvm_inject_size_fault(vcpu); + return 1; + } + + /* Falls between the IPA range and the PARange? */ + if (fault_ipa >= BIT_ULL(vcpu->arch.hw_mmu->pgt->ia_bits)) { + fault_ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0); + + if (is_iabt) + kvm_inject_pabt(vcpu, fault_ipa); + else + kvm_inject_dabt(vcpu, fault_ipa); + return 1; + } + } + /* Synchronous External Abort? */ if (kvm_vcpu_abt_issea(vcpu)) { /* -- 2.20.1