Messages in this thread | | | From | Andy Lutomirski <> | Date | Fri, 23 Aug 2019 15:46:20 -0700 | Subject | Re: [PATCH] KVM: x86: Don't update RIP or do single-step on faulting emulation |
| |
On Fri, Aug 23, 2019 at 1:55 PM Sean Christopherson <sean.j.christopherson@intel.com> wrote: > > Don't advance RIP or inject a single-step #DB if emulation signals a > fault. This logic applies to all state updates that are conditional on > clean retirement of the emulation instruction, e.g. updating RFLAGS was > previously handled by commit 38827dbd3fb85 ("KVM: x86: Do not update > EFLAGS on faulting emulation"). > > Not advancing RIP is likely a nop, i.e. ctxt->eip isn't updated with > ctxt->_eip until emulation "retires" anyways. Skipping #DB injection > fixes a bug reported by Andy Lutomirski where a #UD on SYSCALL due to > invalid state with RFLAGS.RF=1 would loop indefinitely due to emulation
EFLAGS.TF=1
| |