On 29/03/2018 23:48, Sean Christopherson wrote: > Revert a recent change to return RET_PF_EMULATE instead of -EFAULT > when handling an invalid HVA during a page fault, and resolve the > original bug by removing a bogus WARN_ON in handle_ept_misconfig. > > I came across the new behavior of RET_PF_EMULATE while testing > failure scenarios related to handling faults on remapped PFNs, > e.g. VMAs with VM_PFNMAP set. In one scenario I wanted to confirm > KVM behavior when my fault handler (associated with the VMA) could > not insert a PFN, e.g. due to unresolvable resource contention. > Rather than the expected -EFAULT (or similar death), Qemu spat out > an emulation failure, which led me down this rabbit hole... > > I tried a variety of alternative approaches to fixing the original > bug, e.g. returning RET_PF_EMULATE only for MMIO or adding a new > return type, but eventually I came to the conclusion that the > handle_ept_misconfig() behavior is simply wrong. There's (a lot) > more analysis in the revert commit. > > > Sean Christopherson (2): > Revert "KVM: X86: Fix SMRAM accessing even if VM is shutdown" > KVM: VMX: remove bogus WARN_ON in handle_ept_misconfig > > arch/x86/kvm/mmu.c | 2 +- > arch/x86/kvm/vmx.c | 13 +------------ > 2 files changed, 2 insertions(+), 13 deletions(-) > Queued, thanks! Paolo
