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Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Jesper Dangaard Brouer , Ilias Apalodimas References: <20241107212309.3097362-1-almasrymina@google.com> <20241107212309.3097362-5-almasrymina@google.com> <20241108141812.GL35848@ziepe.ca> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/8/24 15:58, Stanislav Fomichev wrote: > On 11/08, Jason Gunthorpe wrote: >> On Thu, Nov 07, 2024 at 09:23:08PM +0000, Mina Almasry wrote: >>> dmabuf dma-addresses should not be dma_sync'd for CPU/device. Typically >>> its the driver responsibility to dma_sync for CPU, but the driver should >>> not dma_sync for CPU if the netmem is actually coming from a dmabuf >>> memory provider. >> >> This is not completely true, it is not *all* dmabuf, just the parts of >> the dmabuf that are actually MMIO. >> >> If you do this you may want to block accepting dmabufs that have CPU >> pages inside them. > > We still want udmabufs to work, so probably need some new helper to test > whether a particular netmem is backed by the cpu memory? Agree. I guess it's fair to assume that page pool is backed either by one or another, so could be a page pool flag that devmem.c can set on init. -- Pavel Begunkov