On Thu, 26 Sep 2019 at 15:12, Matthew Rosato <[email protected]> wrote: > > The fix in dbe9cf606c shrinks the IOMMU memory region to a size > that seems reasonable on the surface, however is actually too > small as it is based against a 0-mapped address space. This > causes breakage with small guests as they can overrun the IOMMU window. > > Let's go back to the prior method of initializing iommu for now. > > Fixes: dbe9cf606c ("s390x/pci: Set the iommu region size mpcifc request") > Reported-by: Boris Fiuczynski <[email protected]> > Reported-by: Stefan Zimmerman <[email protected]> > Signed-off-by: Matthew Rosato <[email protected]>
So in commit f0a399dbae6a2d0e2 (Nov 2015) we used "pal - pba + 1". In commit f7c40aa1e7feb50bc4 (June 2016) we switched to "pal + 1". In commit dbe9cf606c (Jan 2019) we went back to "pal - pba + 1" Now we're on "pal + 1" again... Are we really sure that this is correct and that we're not just going to keep looping around between these two formations forever? :-) thanks -- PMM
