> -----Original Message----- > From: Tian, Kevin <kevin.t...@intel.com> > Sent: 25 November 2019 08:22 > To: Durrant, Paul <pdurr...@amazon.com>; xen-devel@lists.xenproject.org > Cc: Jan Beulich <jbeul...@suse.com>; Andrew Cooper > <andrew.coop...@citrix.com>; Wei Liu <w...@xen.org>; Roger Pau Monné > <roger....@citrix.com> > Subject: RE: [PATCH] x86 / iommu: set up a scratch page in the quarantine > domain > > > From: Paul Durrant [mailto:pdurr...@amazon.com] > > Sent: Wednesday, November 20, 2019 8:09 PM > > > > This patch introduces a new iommu_op to facilitate a per-implementation > > quarantine set up, and then further code for x86 implementations > > (amd and vtd) to set up a read/wrote scratch page to serve as the > source/ > > target for all DMA whilst a device is assigned to dom_io. > > > > The reason for doing this is that some hardware may continue to re-try > > DMA, despite FLR, in the event of an error. Having a scratch page mapped > > will allow pending DMA to drain and thus quiesce such buggy hardware. > > then there is no diagnostics at all since all faults are quiescent now... > why do we want to support such buggy hardware? Is it better to make > it an default-off option since buggy is supposed to niche case?
I guess it could be a command line option... perhaps making the new 'iommu=quarantine' boolean into something more complex, but I'm not sure it's really worth it. Perhaps a compile time option would be better? Paul _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
