> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 05 October 2018 12:18 > To: George Dunlap <george.dun...@citrix.com>; Paul Durrant > <paul.durr...@citrix.com> > Cc: Andrew Cooper <andrew.coop...@citrix.com>; Ian Jackson > <ian.jack...@citrix.com>; Wei Liu <wei.l...@citrix.com>; Stefano > Stabellini <sstabell...@kernel.org>; xen-devel <xen- > de...@lists.xenproject.org>; Konrad Rzeszutek Wilk > <konrad.w...@oracle.com>; Tim (Xen.org) <t...@xen.org> > Subject: RE: [Xen-devel] [PATCH v14 4/9] iommu: don't domain_crash() > inside iommu_map/unmap_page() > > >>> On 05.10.18 at 12:38, <paul.durr...@citrix.com> wrote: > >> From: George Dunlap > >> Sent: 05 October 2018 11:35 > >> > >> > On Oct 5, 2018, at 11:27 AM, Paul Durrant <paul.durr...@citrix.com> > >> wrote: > >> > But for mapping too? It seems unnecessary to crash the domain in that > >> case. > >> > >> ISTR that the domain_crash() was added only a few years ago; I’d have > to > >> go back and see the reasoning for it being added in the first place. > I’ll > >> do that Monday if Jan doesn’t beat me to it. > >> > > > > I was added by the following commit: > > > > commit 834c97baebb3743c54bcae228e984ae1b9692e6a > > Author: Quan Xu <quan...@intel.com> > > Date: Tue Jun 14 15:10:57 2016 +0200 > > > > IOMMU: handle IOMMU mapping and unmapping failures > > > > Treat IOMMU mapping and unmapping failures as a fatal to the DomU > > If IOMMU mapping and unmapping failed, crash the DomU and propagate > > the error up to the call trees. > > > > No spamming of the log can occur. For DomU, we avoid logging any > > message for already dying domains. For Dom0, that'll still be more > > verbose than we'd really like, but it at least wouldn't outright > > flood the console. > > > > Signed-off-by: Quan Xu <quan...@intel.com> > > Reviewed-by: Kevin Tian <kevin.t...@intel.com> > > Reviewed-by: Jan Beulich <jbeul...@suse.com> > > > > So the justification appears to be to avoid log spam. > > Iirc that part of the description only exists because early version of > that patch did introduce log spam. > > The problem iirc is mainly proper error handling, in particular proper > unwinding of earlier mappings that may have got installed > successfully in the context of the same hypercall (or whatever). >
Ok. In the interest of making progress let's just drop this patch altogether. I'll add a patch to introduce a no-crash variant for map into my series implementing PV-IOMMU. Paul > Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
