From: Simon Horman <horms@kernel.org>
To: Dexuan Cui <decui@microsoft.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
longli@microsoft.com, andrew+netdev@lunn.ch, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
kotaranov@microsoft.com, ernis@linux.microsoft.com,
dipayanroy@linux.microsoft.com, kees@kernel.org,
jacob.e.keller@intel.com, ssengar@linux.microsoft.com,
linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH net] net: mana: Sync page pool RX frags for CPU
Date: Fri, 19 Jun 2026 10:05:14 +0100 [thread overview]
Message-ID: <20260619090514.GT827683@horms.kernel.org> (raw)
In-Reply-To: <20260618035029.249361-1-decui@microsoft.com>
On Wed, Jun 17, 2026 at 08:50:29PM -0700, Dexuan Cui wrote:
> MANA allocates RX buffers from page pool fragments when frag_count is
> greater than 1. In that case the buffers remain DMA mapped by page pool
> and the RX completion path does not call dma_unmap_single(). As a result,
> the implicit sync-for-CPU normally performed by dma_unmap_single() is
> missing before the packet data is passed to the networking stack.
>
> This breaks RX on configurations which require explicit DMA syncing, for
> example when booted with swiotlb=force.
>
> Fix this by recording the page pool page and DMA sync offset when the RX
> buffer is allocated, and syncing the received packet range for CPU access
> before handing the RX buffer to the stack.
>
> Also validate the packet length reported in the RX CQE before using it as
> a DMA sync length or passing it to skb processing. The CQE is supplied
> by the device and should not be blindly trusted by Confidential VMs.
I think this last part warrants being split out into a separate patch.
>
> Fixes: 730ff06d3f5c ("net: mana: Use page pool fragments for RX buffers instead of full pages to improve memory efficiency.")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
...
prev parent reply other threads:[~2026-06-19 9:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-18 3:50 [PATCH net] net: mana: Sync page pool RX frags for CPU Dexuan Cui
2026-06-18 18:38 ` Haiyang Zhang
2026-06-19 9:05 ` Simon Horman [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260619090514.GT827683@horms.kernel.org \
--to=horms@kernel.org \
--cc=andrew+netdev@lunn.ch \
--cc=davem@davemloft.net \
--cc=decui@microsoft.com \
--cc=dipayanroy@linux.microsoft.com \
--cc=edumazet@google.com \
--cc=ernis@linux.microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=jacob.e.keller@intel.com \
--cc=kees@kernel.org \
--cc=kotaranov@microsoft.com \
--cc=kuba@kernel.org \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rdma@vger.kernel.org \
--cc=longli@microsoft.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=ssengar@linux.microsoft.com \
--cc=stable@vger.kernel.org \
--cc=wei.liu@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox