On Wed, Dec 06, 2023 at 11:38:09AM -0400, Jason Gunthorpe wrote: > On Wed, Dec 06, 2023 at 04:18:05PM +0100, Lorenzo Pieralisi wrote: > > On Wed, Dec 06, 2023 at 11:05:56AM -0400, Jason Gunthorpe wrote: > > > On Wed, Dec 06, 2023 at 02:49:02PM +0000, Catalin Marinas wrote: > > > > BTW, on those Mellanox devices that require different attributes within > > > > a BAR, do they have a problem with speculative reads causing > > > > side-effects? > > > > > > Yes. We definitely have had that problem in the past on older > > > devices. VFIO must map the BAR using pgprot_device/noncached() into > > > the VMM, no other choice is functionally OK. > > > > Were those BARs tagged as prefetchable or non-prefetchable ? I assume the > > latter but please let me know if I am guessing wrong. > > I don't know it was quite old HW. Probably. > > Just because a BAR is not marked as prefetchable doesn't mean that the > device can't use NORMAL_NC on subsets of it. What about the other way around - would we have a prefetchable BAR that has portions which are unprefetchable? -- Catalin
