Subject: Re: [PATCH net-next] net: mana: Force single RX buffer per page for CVM/encrypted guest memory

From: Jakub Kicinski <[email-masked]>
Date: Mon, 27 Apr 2026 16:21:00 -0700

On Mon, 27 Apr 2026 06:51:02 -0700 Dipayaan Roy wrote:
> When page_pool allocates sub-page RX buffer fragments, the bounce buffer
> granularity may not align with these smaller fragment sizes, leading to
> failure in mana driver rx path.
> 
> Refactor the RX buffer decision into mana_use_single_rxbuf_per_page().
> When cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) is true, the driver is
> forced to use a single RX buffer per page. This ensures:
> - Each RX buffer is exactly one PAGE_SIZE.
> - The DMA offset is always 0.
> - SWIOTLB maps full, page-aligned blocks.

As commented on your RFC - I'm not sure why you need this.