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Thu, 08 Jan 2026 06:18:22 -0800 (PST) Received: from sgarzare-redhat ([193.207.223.215]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b842a22ff58sm817309166b.6.2026.01.08.06.18.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jan 2026 06:18:22 -0800 (PST) Date: Thu, 8 Jan 2026 15:18:13 +0100 From: Stefano Garzarella To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, 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 , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Petr Tesarik , Leon Romanovsky , Jason Gunthorpe , Bartosz Golaszewski , 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: Re: [PATCH v2 07/15] vsock/virtio: fix DMA alignment for event_list Message-ID: References: <20260108090639-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260108090639-mutt-send-email-mst@kernel.org> On Thu, Jan 08, 2026 at 09:07:53AM -0500, Michael S. Tsirkin wrote: >On Thu, Jan 08, 2026 at 03:04:07PM +0100, Stefano Garzarella wrote: >> On Mon, Jan 05, 2026 at 03:23:17AM -0500, Michael S. Tsirkin wrote: >> > 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 event_list array is used for DMA_FROM_DEVICE operations via >> > virtqueue_add_inbuf(). The adjacent event_run and guest_cid fields are >> > written by the CPU while the buffer is available, so mapped for the >> > device. If these share cachelines with event_list, CPU writes can >> > corrupt DMA data. >> > >> > Add __dma_from_device_group_begin()/end() annotations to ensure event_list >> > is isolated in its own cachelines. >> > >> > Signed-off-by: Michael S. Tsirkin >> > --- >> > net/vmw_vsock/virtio_transport.c | 4 +++- >> > 1 file changed, 3 insertions(+), 1 deletion(-) >> > >> > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >> > index 8c867023a2e5..bb94baadfd8b 100644 >> > --- a/net/vmw_vsock/virtio_transport.c >> > +++ b/net/vmw_vsock/virtio_transport.c >> > @@ -17,6 +17,7 @@ >> > #include >> > #include >> > #include >> > +#include >> > #include >> > #include >> > #include >> > @@ -59,8 +60,9 @@ struct virtio_vsock { >> > */ >> > struct mutex event_lock; >> > bool event_run; >> > + __dma_from_device_group_begin(); >> > struct virtio_vsock_event event_list[8]; >> > - >> > + __dma_from_device_group_end(); >> >> Can we keep the blank line before `guest_cid` so that the comment before >> this section makes sense? (regarding the lock required to access these >> fields) >> >> Thanks, >> Stefano > >A follow up patch re-introduces it, so I don't think it matters? Yes, I saw it later. Of course I don't want you to resend the whole series just for this. So if you have to resend the series for other reasons, I would avoid removing the line here because I don't see any value on removing it and add back later. In both cases: Acked-by: Stefano Garzarella > >> > u32 guest_cid; >> > bool seqpacket_allow; >> > >> > -- >> > MST >> > >