From af7c1beccfd98bad752644dc14ea93805d65b2c9 Mon Sep 17 00:00:00 2001 From: Baoyou Xie Date: Thu, 1 Sep 2016 19:02:57 +0800 Subject: virtio: mark vring_dma_dev() static We get 1 warning when building kernel with W=1: drivers/virtio/virtio_ring.c:170:16: warning: no previous prototype for 'vring_dma_dev' [-Wmissing-prototypes] In fact, this function is only used in the file in which it is declared and don't need a declaration, but can be made static. so this patch marks this function with 'static'. Signed-off-by: Baoyou Xie Acked-by: Arnd Bergmann Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index e383ecdaca59..ed9c9eeedfe5 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -167,7 +167,7 @@ static bool vring_use_dma_api(struct virtio_device *vdev) * making all of the arch DMA ops work on the vring device itself * is a mess. For now, we use the parent device for DMA ops. */ -struct device *vring_dma_dev(const struct vring_virtqueue *vq) +static struct device *vring_dma_dev(const struct vring_virtqueue *vq) { return vq->vq.vdev->dev.parent; } -- cgit v1.2.3-58-ga151 From 5e59d9a1aed26abcc79abe78af5cfd34e53cbe7f Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 30 Aug 2016 08:04:15 -0700 Subject: virtio_console: Stop doing DMA on the stack virtio_console uses a small DMA buffer for control requests. Move that buffer into heap memory. Doing virtio DMA on the stack is normally okay on non-DMA-API virtio systems (which is currently most of them), but it breaks completely if the stack is virtually mapped. Tested by typing both directions using picocom aimed at /dev/hvc0. Signed-off-by: Andy Lutomirski Signed-off-by: Michael S. Tsirkin Reviewed-by: Amit Shah --- drivers/char/virtio_console.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index d2406fe25533..5da47e26a012 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -165,6 +165,12 @@ struct ports_device { */ struct virtqueue *c_ivq, *c_ovq; + /* + * A control packet buffer for guest->host requests, protected + * by c_ovq_lock. + */ + struct virtio_console_control cpkt; + /* Array of per-port IO virtqueues */ struct virtqueue **in_vqs, **out_vqs; @@ -560,28 +566,29 @@ static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id, unsigned int event, unsigned int value) { struct scatterlist sg[1]; - struct virtio_console_control cpkt; struct virtqueue *vq; unsigned int len; if (!use_multiport(portdev)) return 0; - cpkt.id = cpu_to_virtio32(portdev->vdev, port_id); - cpkt.event = cpu_to_virtio16(portdev->vdev, event); - cpkt.value = cpu_to_virtio16(portdev->vdev, value); - vq = portdev->c_ovq; - sg_init_one(sg, &cpkt, sizeof(cpkt)); - spin_lock(&portdev->c_ovq_lock); - if (virtqueue_add_outbuf(vq, sg, 1, &cpkt, GFP_ATOMIC) == 0) { + + portdev->cpkt.id = cpu_to_virtio32(portdev->vdev, port_id); + portdev->cpkt.event = cpu_to_virtio16(portdev->vdev, event); + portdev->cpkt.value = cpu_to_virtio16(portdev->vdev, value); + + sg_init_one(sg, &portdev->cpkt, sizeof(struct virtio_console_control)); + + if (virtqueue_add_outbuf(vq, sg, 1, &portdev->cpkt, GFP_ATOMIC) == 0) { virtqueue_kick(vq); while (!virtqueue_get_buf(vq, &len) && !virtqueue_is_broken(vq)) cpu_relax(); } + spin_unlock(&portdev->c_ovq_lock); return 0; } -- cgit v1.2.3-58-ga151