From c4ad98e4b72cb5be30ea282fce935248f2300e62 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 15 Sep 2020 11:42:17 +0100 Subject: KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch KVM currently assumes that an instruction abort can never be a write. This is in general true, except when the abort is triggered by a S1PTW on instruction fetch that tries to update the S1 page tables (to set AF, for example). This can happen if the page tables have been paged out and brought back in without seeing a direct write to them (they are thus marked read only), and the fault handling code will make the PT executable(!) instead of writable. The guest gets stuck forever. In these conditions, the permission fault must be considered as a write so that the Stage-1 update can take place. This is essentially the I-side equivalent of the problem fixed by 60e21a0ef54c ("arm64: KVM: Take S1 walks into account when determining S2 write faults"). Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce kvm_vcpu_trap_is_exec_fault() that only return true when no faulting on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't specific to data abort. Signed-off-by: Marc Zyngier Reviewed-by: Will Deacon Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org --- arch/arm64/kvm/mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/arm64/kvm/mmu.c') diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index f58d657a898d..9aec1ce491d2 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1843,7 +1843,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_s2_mmu *mmu = vcpu->arch.hw_mmu; write_fault = kvm_is_write_fault(vcpu); - exec_fault = kvm_vcpu_trap_is_iabt(vcpu); + exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu); VM_BUG_ON(write_fault && exec_fault); if (fault_status == FSC_PERM && !write_fault && !exec_fault) { @@ -2125,7 +2125,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) goto out; } - if (kvm_vcpu_dabt_iss1tw(vcpu)) { + if (kvm_vcpu_abt_iss1tw(vcpu)) { kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); ret = 1; goto out_unlock; -- cgit v1.2.3