On Thu, Nov 02, 2017 at 10:36:35AM +0000, Marc Zyngier wrote: > On Wed, Nov 01 2017 at 11:17:27 am GMT, Andrew Jones <[email protected]> > wrote: > > On Mon, Oct 23, 2017 at 05:11:19PM +0100, Marc Zyngier wrote: > >> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > >> index 2174244f6317..0417c8e2a81c 100644 > >> --- a/virt/kvm/arm/mmu.c > >> +++ b/virt/kvm/arm/mmu.c > >> @@ -1292,7 +1292,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, > >> phys_addr_t fault_ipa, > >> unsigned long fault_status) > >> { > >> int ret; > >> - bool write_fault, writable, hugetlb = false, force_pte = false; > >> + bool write_fault, exec_fault, writable, hugetlb = false, force_pte = > >> false; > >> unsigned long mmu_seq; > >> gfn_t gfn = fault_ipa >> PAGE_SHIFT; > >> struct kvm *kvm = vcpu->kvm; > >> @@ -1304,7 +1304,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, > >> phys_addr_t fault_ipa, > >> unsigned long flags = 0; > >> > >> write_fault = kvm_is_write_fault(vcpu); > >> - if (fault_status == FSC_PERM && !write_fault) { > >> + exec_fault = kvm_vcpu_trap_is_iabt(vcpu); > >> + VM_BUG_ON(write_fault && exec_fault); > > > > This VM_BUG_ON can never fire as long as kvm_is_write_fault() is > > defined as > > > > { > > if (kvm_vcpu_trap_is_iabt(vcpu)) > > return false; > > return kvm_vcpu_dabt_iswrite(vcpu); > > } > > That's indeed what I expect. But given that the code now relies on this > property, I chose to make it explicit. > > Or are you seeing a better way of making this an invariant? >
No, I wish I did, because then I wouldn't have to apologize for the noise :-) The VM_BUG_ON() does indeed improve the code by documenting/ enforcing the requirement. Thanks, drew _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
