Jason Gunthorpe <[email protected]> writes: > On Mon, Aug 10, 2026 at 12:46:51PM +0100, Will Deacon wrote: >> On Mon, Aug 10, 2026 at 01:37:11PM +0200, Marek Szyprowski wrote: >> > On 10.08.2026 12:20, Will Deacon wrote: >> > > On Mon, Aug 10, 2026 at 02:59:42PM +0530, Aneesh Kumar K.V wrote: >> > >> Marek Szyprowski <[email protected]> writes: >> > >> >> > >>> On 07.08.2026 20:20, Jason Gunthorpe wrote: >> > >>>> On Fri, Aug 07, 2026 at 06:13:49PM +0000, Mostafa Saleh wrote: >> > >>>>> But the whole thing is best effort anyway, the kernel picks >> > >>>>> IO_TLB_DEFAULT_SIZE which does not depend on the system topology or >> > >>>>> how many devices or how much DMA they do. >> > >>>>> SWIOTLB memory is wasted if unused so we should be careful around >> > >>>>> that as it would be the other way around and users would have to >> > >>>>> decrease it manually. >> > >>>> Yeah, it is why the arch code shouldn't really be sizing it directly, >> > >>>> it should be done in common code and, yes, we are probably going to >> > >>>> have to do something alot smarter to have the common code better >> > >>>> auto-tune this for the CC case.. >> > >>> What about the $subject patch? I assume that it is still needed to >> > >>> >> > >>> restore the behavior that was altered by the "[PATCH v8 00/23] >> > >>> >> > >>> dma-mapping: Track shared DMA state through direct, pool and swiotlb >> > >>> >> > >>> paths?" patchset? >> > >>> >> > >> I would request that we pick this patch to fix the regression described >> > >> in https://lore.kernel.org/all/[email protected]/. >> > > I really don't think we need it. CCA hardware isn't exactly widespread >> > > and the KVM host side patches don't appear close to being merged. >> > >> > Does this mean that the branch for-next/coco [1] won't go to v7.3-rc1? > > Let's not make progress on guest support contingent on KVM CCA host > side patches please. I expect the CSPs will have VM instance types > available based on CCA within quarters, and Linux as a Guest should > work in those environments regardless of what KVM is doing. I don't > really expect full KVM support for years, frankly, the patchset is > massive. Even Intel and AMD don't have full KVM support yet. > > People already have CCA capable HW, are already testing this stuff and > the closer upstream can get to being workable as a guest without a > mountain of OOT patches the better. > > I agree the thing is not ideal, but it was merged to ARM like this a > long time ago, this patch is just fixing a small oopsie (was it a > merge conflict?) to put it back. I don't the objection. >
It was not a merge conflict issue. The change was introduced by an incorrect rebase I did when updating the patch series on top of the pKVM changes. -aneesh
