On Fri, Aug 07, 2026 at 02:18:31PM +0100, Will Deacon wrote: > > I was under the impression that there is a possibility of using swiotlb > > instead of restricted-dma-pool with pKVM. > > Yes, that patch enables swiotlb as a possibility for protected guests > but with your patch we avoid shrinking the swiotlb buffer even when > restricted dma pools are being used and that's a waste of memory.
I also thought we switched pkvm to use CC-like swiotlb as part of the alignment in this rework? Mostafa ? > > If that is not the case, then we could change: > > > > !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && > > > > to > > > > !is_realm_world() && > > Perhaps, or you could just pass the swiotlb= option if the defaults don't > work for you. Can you give more details about the slots exhaustion you're > seeing under CCA? We see badness with swiotlb too, it basically doesn't work out of the box if you have to use it 100% for real devices. It easily runs out of memory. Auto tuning to higher levels makes sense to me, but I'd rather the core code handled adjusting its size to the estimated need, not arch code. Jason
