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[80.230.31.118]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47be3aea77bsm247750305e9.17.2025.12.30.02.16.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Dec 2025 02:16:17 -0800 (PST) Date: Tue, 30 Dec 2025 05:16:14 -0500 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Cong Wang , Jonathan Corbet , Olivia Mackall , Herbert Xu , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Eugenio =?utf-8?B?UMOpcmV6?= , "James E.J. Bottomley" , "Martin K. Petersen" , Gerd Hoffmann , Xuan Zhuo , Marek Szyprowski , Robin Murphy , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Petr Tesarik , Leon Romanovsky , Jason Gunthorpe , linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, virtualization@lists.linux.dev, linux-scsi@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH RFC 09/13] virtio_input: fix DMA alignment for evts Message-ID: <5f57d7dc13920517b3ed3e56d815ad1ba4cf36ce.1767089672.git.mst@redhat.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On non-cache-coherent platforms, when a structure contains a buffer used for DMA alongside fields that the CPU writes to, cacheline sharing can cause data corruption. The evts array is used for DMA_FROM_DEVICE operations via virtqueue_add_inbuf(). The adjacent lock and ready fields are written by the CPU during normal operation. If these share cachelines with evts, CPU writes can corrupt DMA data. Add __dma_from_device_aligned_begin/end annotations to ensure evts is isolated in its own cachelines. Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_input.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c index d0728285b6ce..774494754a99 100644 --- a/drivers/virtio/virtio_input.c +++ b/drivers/virtio/virtio_input.c @@ -4,6 +4,7 @@ #include #include #include +#include =20 #include #include @@ -16,7 +17,9 @@ struct virtio_input { char serial[64]; char phys[64]; struct virtqueue *evt, *sts; + __dma_from_device_aligned_begin struct virtio_input_event evts[64]; + __dma_from_device_aligned_end spinlock_t lock; bool ready; }; --=20 MST