On 17/08/2017 11:00, Paolo Bonzini wrote: > On 17/08/2017 00:31, Michael S. Tsirkin wrote: >> On Wed, Aug 16, 2017 at 11:25:35PM +0200, Paolo Bonzini wrote: >>> Yes, I agree. EMULTYPE_SKIP is fine because failed decoding still >>> causes an exception to be injected. Maybe it's better to gate the >>> EMULTYPE_SKIP emulation on the exit qualification saying this is a write >> >> I thought it's already limited to writes. I agree that's a reasonable >> limitation in any case. >> >>> and also not a page table walk---just in case. >> >> I still don't get it, sorry. Let's assume for the sake of argument >> that it's a PT walk causing the MMIO access. Just why do you think >> that it makes sense to skip the instruction that caused the walk? > > I think it doesn't. I think in that case it's better to skip the fast > write and proceed with full emulation. ... nope, exit qualification is just zero for EPT misconfigurations, so we cannot do this. Paolo