Re: [PATCH net v4 3/4] netdevsim: support devmem RX and TX bindings

[Stanislav Fomichev]

On 10/15, Mina Almasry wrote:
> Set a 64-bit DMA mask on nsim_bus_dev, enable NETMEM_TX_DMA on the
> netdevsim net_device, and configure page_pool instances with
> PP_FLAG_ALLOW_UNREADABLE_NETMEM and queue_idx, plus PP_FLAG_DMA_MAP |
> PP_FLAG_DMA_SYNC_DEV when CONFIG_HAS_DMA is set, so devmem bind-rx and
> bind-tx netlink operations can be tested against netdevsim in software
> selftests.
> 
> The pp_hold debugfs file allocates pages from the queue 0 page pool, so
> refuse it when that pool is backed by a memory provider, and take the
> netdev instance lock there so a concurrent bind-rx cannot swap the pool
> in between. The software PSP path checksums the payload when the peer
> does not decapsulate, so drop unreadable skbs there.
> 
> Cc: Tariq Toukan <tariqt@xxxxxxxxxx>
> Cc: Kaifeng Wang <kaifengw@xxxxxxxxxx>
> Assisted-by: LLM
> Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
> Reviewed-by: Dragos Tatulea <dtatulea@xxxxxxxxxx>

Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>