On Sat, Jul 27, 2019 at 10:38:03AM -0700, Andy Lutomirski wrote: > On Fri, Jul 26, 2019 at 10:52 PM Sean Christopherson > <sean.j.christopherson@xxxxxxxxx> wrote: > > > > Similar to the existing AMD #NPF case where emulation of the current > > instruction is not possible due to lack of information, virtualization > > of Intel SGX will introduce a scenario where emulation is not possible > > due to the VMExit occurring in an SGX enclave. And again similar to > > the AMD case, emulation can be initiated by kvm_mmu_page_fault(), i.e. > > outside of the control of the vendor-specific code. > > > > While the cause and architecturally visible behavior of the two cases > > is different, e.g. Intel SGX will inject a #UD whereas AMD #NPF is a > > clean resume or complete shutdown, the impact on the common emulation > > code is identical: KVM must stop emulation immediately and resume the > > guest. > > > > Replace the exisiting need_emulation_on_page_fault() with a more generic > > is_emulatable() kvm_x86_ops callback, which is called unconditionally > > by x86_emulate_instruction(). > > > > Having recently noticed that emulate_ud() is broken when the guest's > TF is set, I suppose I should ask: does your new code function > sensibly when TF is set? Barring a VMX fault injection interaction I'm not thinking of, yes. The SGX reaction to the #UD VM-Exit is to inject a #UD and resume the guest, pending breakpoints shouldn't be affected in any way (unless some other part of KVM mucks with them, e.g. when guest single-stepping is enabled).
