> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 28 March 2018 16:59 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: Andrew Cooper <andrew.coop...@citrix.com>; xen-devel <xen- > de...@lists.xenproject.org> > Subject: RE: possible I/O emulation state machine issue > > >>> On 28.03.18 at 15:48, <paul.durr...@citrix.com> wrote: > >> -----Original Message----- > >> From: Jan Beulich [mailto:jbeul...@suse.com] > >> Sent: 26 March 2018 09:43 > >> To: Paul Durrant <paul.durr...@citrix.com> > >> Cc: Andrew Cooper <andrew.coop...@citrix.com>; xen-devel <xen- > >> de...@lists.xenproject.org> > >> Subject: Re: possible I/O emulation state machine issue > >> > >> >>> On 23.03.18 at 14:41, <paul.durr...@citrix.com> wrote: > >> > So somehow it appears the vcpu got back into guest and executed the > next > >> > instruction whilst there was pending I/O. > >> > >> Two new pieces of information, in case either rings a bell: > >> > > > > Alas neither rings a bell. > > > >> The issue appears to never occur in hap=0 mode. > >> > > > > That's quite an odd correlation. > > Simply timing, perhaps. In any event, newest logs suggest we have > an issue with Windows paging out the page the data for the > REP OUTSW is coming from while the port I/O part of the operation > is pending qemu's completion. Upon retry the linear->physical > translation fails, and we leave incorrect state in place. > > I thought we cache the translation result, thus avoiding the need > for a translation during the retry cycle, so either I'm misremembering > or this doesn't work as intended. And in fact doing the translation a > second time (with the potential of it failing) is wrong here - when the > port access has occurred, we must not fail the emulation anymore > (repeating the port write would probably be fine for the VGA, but > would hardly be fine for e.g. an IDE interface). >
Yes, I thought we made sure all reps were completed using cached translations before returning to guest. Paul > Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
