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authorPeter Maydell <peter.maydell@linaro.org>2012-01-06 16:44:19 +0000
committerPeter Maydell <peter.maydell@linaro.org>2012-03-03 21:48:08 +0000
commit9969507eb502b845ab1135d95623f50be093080b (patch)
treeec9ab3ac6e0c0a423201141bf60eb513fcfa4731
parent116364bd8e654646aaf79591077ac0c4b9b7c3fa (diff)
downloadqemu-arm-9969507eb502b845ab1135d95623f50be093080b.tar.gz
virtio: Support transports which can specify the vring alignment
Support virtio transports which can specify the vring alignment (ie where the guest communicates this to the host) by providing a new virtio_queue_set_align() function. (The default alignment remains as before.) FIXME save/load support for this new field! Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--hw/virtio.c14
-rw-r--r--hw/virtio.h1
2 files changed, 13 insertions, 2 deletions
diff --git a/hw/virtio.c b/hw/virtio.c
index 22ea8181c0..e759b58ead 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -19,7 +19,9 @@
#include "qemu-barrier.h"
/* The alignment to use between consumer and producer parts of vring.
- * x86 pagesize again. */
+ * x86 pagesize again. This is the default, used by transports like PCI
+ * which don't provide a means for the guest to tell the host the alignment.
+ */
#define VIRTIO_PCI_VRING_ALIGN 4096
typedef struct VRingDesc
@@ -53,6 +55,7 @@ typedef struct VRingUsed
typedef struct VRing
{
unsigned int num;
+ unsigned int align;
target_phys_addr_t desc;
target_phys_addr_t avail;
target_phys_addr_t used;
@@ -90,7 +93,7 @@ static void virtqueue_init(VirtQueue *vq)
vq->vring.avail = pa + vq->vring.num * sizeof(VRingDesc);
vq->vring.used = vring_align(vq->vring.avail +
offsetof(VRingAvail, ring[vq->vring.num]),
- VIRTIO_PCI_VRING_ALIGN);
+ vq->vring.align);
}
static inline uint64_t vring_desc_addr(target_phys_addr_t desc_pa, int i)
@@ -630,6 +633,12 @@ int virtio_queue_get_num(VirtIODevice *vdev, int n)
return vdev->vq[n].vring.num;
}
+void virtio_queue_set_align(VirtIODevice *vdev, int n, int align)
+{
+ vdev->vq[n].vring.align = align;
+ virtqueue_init(&vdev->vq[n]);
+}
+
void virtio_queue_notify_vq(VirtQueue *vq)
{
if (vq->vring.desc) {
@@ -670,6 +679,7 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
abort();
vdev->vq[i].vring.num = queue_size;
+ vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;
vdev->vq[i].handle_output = handle_output;
return &vdev->vq[i];
diff --git a/hw/virtio.h b/hw/virtio.h
index 1f5aa57075..311e7e4e2a 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -180,6 +180,7 @@ void virtio_queue_set_addr(VirtIODevice *vdev, int n, target_phys_addr_t addr);
target_phys_addr_t virtio_queue_get_addr(VirtIODevice *vdev, int n);
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num);
int virtio_queue_get_num(VirtIODevice *vdev, int n);
+void virtio_queue_set_align(VirtIODevice *vdev, int n, int align);
void virtio_queue_notify(VirtIODevice *vdev, int n);
uint16_t virtio_queue_vector(VirtIODevice *vdev, int n);
void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector);