> -----Original Message----- > From: Andrew Cooper > Sent: 27 November 2018 14:19 > To: Jan Beulich <jbeul...@suse.com>; Paul Durrant > <paul.durr...@citrix.com> > Cc: xen-devel <xen-devel@lists.xenproject.org>; Brian Woods > <brian.wo...@amd.com>; Suravee Suthikulpanit > <suravee.suthikulpa...@amd.com> > Subject: Re: [Xen-devel] [PATCH] amd-iommu: remove page merging code > > On 27/11/2018 13:06, Jan Beulich wrote: > >>>> On 26.11.18 at 18:30, <paul.durr...@citrix.com> wrote: > >> The page merging logic makes use of bits 1-8 and bit 63 of a PTE, which > used > >> to be specified as ignored. However, bits 5 and 6 are now specified as > >> 'accessed' and 'dirty' bits and their use only remains safe as long as > >> the DTE 'Host Access Dirty' bits remain clear. > > Upon second thought - is this actually true with the XSA-275 > > changes in place? As long as the domain is not running yet, > > how would A and/or D bits get set? > > DTE.HAD is an IOMMU control which Xen doesn't currently enable, so this > isn't an issue in current usage.
Yes, that was the point of my comment but I'll clarify that 'remain clear' means that Xen does not set them. Paul > > ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
