diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2025-12-29 18:25:16 -0500 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2026-01-08 09:54:27 -0500 |
| commit | 2678369e8efe0c5ac71adb49fbc2c240a222e44d (patch) | |
| tree | 9cbfa7d5d59848490320300b08f6ec792fd20541 | |
| parent | 95c7b0ad6c69d1c0608ff0bbd358a546856beaf3 (diff) | |
virtio_scsi: fix DMA cacheline issues for events
Current struct virtio_scsi_event_node layout has two problems:
The event (DMA_FROM_DEVICE) and work (CPU-written via
INIT_WORK/queue_work) fields share a cacheline.
On non-cache-coherent platforms, CPU writes to work can
corrupt device-written event data.
If ARCH_DMA_MINALIGN is large enough, the 8 events in event_list share
cachelines, triggering CONFIG_DMA_API_DEBUG warnings.
Fix the corruption by moving event buffers to a separate array and
aligning using __dma_from_device_group_begin()/end().
Suppress the (now spurious) DMA debug warnings using
virtqueue_add_inbuf_cache_clean().
Message-ID: <8801aeef7576a155299f19b6887682dd3a272aba.1767601130.git.mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| -rw-r--r-- | drivers/scsi/virtio_scsi.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 96a69edddbe5..6ff53fc8adb0 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -29,6 +29,7 @@ #include <scsi/scsi_tcq.h> #include <scsi/scsi_devinfo.h> #include <linux/seqlock.h> +#include <linux/dma-mapping.h> #include "sd.h" @@ -61,7 +62,7 @@ struct virtio_scsi_cmd { struct virtio_scsi_event_node { struct virtio_scsi *vscsi; - struct virtio_scsi_event event; + struct virtio_scsi_event *event; struct work_struct work; }; @@ -89,6 +90,11 @@ struct virtio_scsi { struct virtio_scsi_vq ctrl_vq; struct virtio_scsi_vq event_vq; + + __dma_from_device_group_begin(); + struct virtio_scsi_event events[VIRTIO_SCSI_EVENT_LEN]; + __dma_from_device_group_end(); + struct virtio_scsi_vq req_vqs[]; }; @@ -237,12 +243,12 @@ static int virtscsi_kick_event(struct virtio_scsi *vscsi, unsigned long flags; INIT_WORK(&event_node->work, virtscsi_handle_event); - sg_init_one(&sg, &event_node->event, sizeof(struct virtio_scsi_event)); + sg_init_one(&sg, event_node->event, sizeof(struct virtio_scsi_event)); spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); - err = virtqueue_add_inbuf(vscsi->event_vq.vq, &sg, 1, event_node, - GFP_ATOMIC); + err = virtqueue_add_inbuf_cache_clean(vscsi->event_vq.vq, &sg, 1, event_node, + GFP_ATOMIC); if (!err) virtqueue_kick(vscsi->event_vq.vq); @@ -257,6 +263,7 @@ static int virtscsi_kick_event_all(struct virtio_scsi *vscsi) for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) { vscsi->event_list[i].vscsi = vscsi; + vscsi->event_list[i].event = &vscsi->events[i]; virtscsi_kick_event(vscsi, &vscsi->event_list[i]); } @@ -380,7 +387,7 @@ static void virtscsi_handle_event(struct work_struct *work) struct virtio_scsi_event_node *event_node = container_of(work, struct virtio_scsi_event_node, work); struct virtio_scsi *vscsi = event_node->vscsi; - struct virtio_scsi_event *event = &event_node->event; + struct virtio_scsi_event *event = event_node->event; if (event->event & cpu_to_virtio32(vscsi->vdev, VIRTIO_SCSI_T_EVENTS_MISSED)) { |