[PATCH v2 07/15] vsock/virtio: fix DMA alignment for event_list
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2026-01-05 08:23:25
Also in:
kvm, linux-crypto, linux-doc, linux-iommu, linux-scsi, lkml, virtualization
Subsystem:
networking [general], the rest, virtio and vhost vsock driver, virtio core, vm sockets (af_vsock) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Stefan Hajnoczi, Stefano Garzarella, "Michael S. Tsirkin", Jason Wang
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 <mst@redhat.com> --- 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 <linux/virtio_ids.h> #include <linux/virtio_config.h> #include <linux/virtio_vsock.h> +#include <linux/dma-mapping.h> #include <net/sock.h> #include <linux/mutex.h> #include <net/af_vsock.h>
@@ -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(); u32 guest_cid; bool seqpacket_allow;
--
MST