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authoraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2008-12-04 19:52:44 +0000
committeraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2008-12-04 19:52:44 +0000
commit6e02c38dadfe4cf02b0da6135adfd8d9352b90e1 (patch)
tree6de8b1fa9342550d2c7da2be7aef83b80a17a4b0 /hw/virtio-blk.c
parent967f97fa00b2d301584d08c614d446423c65c15a (diff)
Add virtio-blk support
Virtio-blk is a paravirtual block device based on VirtIO. It can be used by specifying the if=virtio parameter to the -drive parameter. When using -enable-kvm, it can achieve very good performance compared to IDE or SCSI. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5870 c046a42c-6fe2-441c-8c8c-71466251a162
Diffstat (limited to 'hw/virtio-blk.c')
-rw-r--r--hw/virtio-blk.c248
1 files changed, 248 insertions, 0 deletions
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
new file mode 100644
index 0000000000..91b90d2030
--- /dev/null
+++ b/hw/virtio-blk.c
@@ -0,0 +1,248 @@
+/*
+ * Virtio Block Device
+ *
+ * Copyright IBM, Corp. 2007
+ *
+ * Authors:
+ * Anthony Liguori <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "virtio-blk.h"
+#include "block_int.h"
+
+typedef struct VirtIOBlock
+{
+ VirtIODevice vdev;
+ BlockDriverState *bs;
+ VirtQueue *vq;
+} VirtIOBlock;
+
+static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
+{
+ return (VirtIOBlock *)vdev;
+}
+
+typedef struct VirtIOBlockReq
+{
+ VirtIOBlock *dev;
+ VirtQueueElement elem;
+ struct virtio_blk_inhdr *in;
+ struct virtio_blk_outhdr *out;
+ size_t size;
+ uint8_t *buffer;
+} VirtIOBlockReq;
+
+static void virtio_blk_rw_complete(void *opaque, int ret)
+{
+ VirtIOBlockReq *req = opaque;
+ VirtIOBlock *s = req->dev;
+
+ /* Copy read data to the guest */
+ if (!ret && !(req->out->type & VIRTIO_BLK_T_OUT)) {
+ size_t offset = 0;
+ int i;
+
+ for (i = 0; i < req->elem.in_num - 1; i++) {
+ size_t len;
+
+ /* Be pretty defensive wrt malicious guests */
+ len = MIN(req->elem.in_sg[i].iov_len,
+ req->size - offset);
+
+ memcpy(req->elem.in_sg[i].iov_base,
+ req->buffer + offset,
+ len);
+ offset += len;
+ }
+ }
+
+ req->in->status = ret ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
+ virtqueue_push(s->vq, &req->elem, req->size + sizeof(*req->in));
+ virtio_notify(&s->vdev, s->vq);
+
+ qemu_free(req->buffer);
+ qemu_free(req);
+}
+
+static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
+{
+ VirtIOBlockReq *req;
+
+ req = qemu_mallocz(sizeof(*req));
+ if (req == NULL)
+ return NULL;
+
+ req->dev = s;
+ if (!virtqueue_pop(s->vq, &req->elem)) {
+ qemu_free(req);
+ return NULL;
+ }
+
+ return req;
+}
+
+static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+ VirtIOBlock *s = to_virtio_blk(vdev);
+ VirtIOBlockReq *req;
+
+ while ((req = virtio_blk_get_request(s))) {
+ int i;
+
+ if (req->elem.out_num < 1 || req->elem.in_num < 1) {
+ fprintf(stderr, "virtio-blk missing headers\n");
+ exit(1);
+ }
+
+ if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
+ req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
+ fprintf(stderr, "virtio-blk header not in correct element\n");
+ exit(1);
+ }
+
+ req->out = (void *)req->elem.out_sg[0].iov_base;
+ req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
+
+ if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
+ unsigned int len = sizeof(*req->in);
+
+ req->in->status = VIRTIO_BLK_S_UNSUPP;
+ virtqueue_push(vq, &req->elem, len);
+ virtio_notify(vdev, vq);
+ qemu_free(req);
+ } else if (req->out->type & VIRTIO_BLK_T_OUT) {
+ size_t offset;
+
+ for (i = 1; i < req->elem.out_num; i++)
+ req->size += req->elem.out_sg[i].iov_len;
+
+ req->buffer = qemu_memalign(512, req->size);
+ if (req->buffer == NULL) {
+ qemu_free(req);
+ break;
+ }
+
+ /* We copy the data from the SG list to avoid splitting up the request. This helps
+ performance a lot until we can pass full sg lists as AIO operations */
+ offset = 0;
+ for (i = 1; i < req->elem.out_num; i++) {
+ size_t len;
+
+ len = MIN(req->elem.out_sg[i].iov_len,
+ req->size - offset);
+ memcpy(req->buffer + offset,
+ req->elem.out_sg[i].iov_base,
+ len);
+ offset += len;
+ }
+
+ bdrv_aio_write(s->bs, req->out->sector,
+ req->buffer,
+ req->size / 512,
+ virtio_blk_rw_complete,
+ req);
+ } else {
+ for (i = 0; i < req->elem.in_num - 1; i++)
+ req->size += req->elem.in_sg[i].iov_len;
+
+ req->buffer = qemu_memalign(512, req->size);
+ if (req->buffer == NULL) {
+ qemu_free(req);
+ break;
+ }
+
+ bdrv_aio_read(s->bs, req->out->sector,
+ req->buffer,
+ req->size / 512,
+ virtio_blk_rw_complete,
+ req);
+ }
+ }
+ /*
+ * FIXME: Want to check for completions before returning to guest mode,
+ * so cached reads and writes are reported as quickly as possible. But
+ * that should be done in the generic block layer.
+ */
+}
+
+static void virtio_blk_reset(VirtIODevice *vdev)
+{
+ /*
+ * This should cancel pending requests, but can't do nicely until there
+ * are per-device request lists.
+ */
+ qemu_aio_flush();
+}
+
+static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
+{
+ VirtIOBlock *s = to_virtio_blk(vdev);
+ struct virtio_blk_config blkcfg;
+ uint64_t capacity;
+ int cylinders, heads, secs;
+
+ bdrv_get_geometry(s->bs, &capacity);
+ bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
+ stq_raw(&blkcfg.capacity, capacity);
+ stl_raw(&blkcfg.seg_max, 128 - 2);
+ stw_raw(&blkcfg.cylinders, cylinders);
+ blkcfg.heads = heads;
+ blkcfg.sectors = secs;
+ memcpy(config, &blkcfg, sizeof(blkcfg));
+}
+
+static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
+{
+ return (1 << VIRTIO_BLK_F_SEG_MAX | 1 << VIRTIO_BLK_F_GEOMETRY);
+}
+
+static void virtio_blk_save(QEMUFile *f, void *opaque)
+{
+ VirtIOBlock *s = opaque;
+ virtio_save(&s->vdev, f);
+}
+
+static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
+{
+ VirtIOBlock *s = opaque;
+
+ if (version_id != 1)
+ return -EINVAL;
+
+ virtio_load(&s->vdev, f);
+
+ return 0;
+}
+
+void *virtio_blk_init(PCIBus *bus, uint16_t vendor, uint16_t device,
+ BlockDriverState *bs)
+{
+ VirtIOBlock *s;
+ int cylinders, heads, secs;
+ static int virtio_blk_id;
+
+ s = (VirtIOBlock *)virtio_init_pci(bus, "virtio-blk", vendor, device,
+ 0, VIRTIO_ID_BLOCK,
+ 0x01, 0x80, 0x00,
+ sizeof(struct virtio_blk_config), sizeof(VirtIOBlock));
+ if (!s)
+ return NULL;
+
+ s->vdev.get_config = virtio_blk_update_config;
+ s->vdev.get_features = virtio_blk_get_features;
+ s->vdev.reset = virtio_blk_reset;
+ s->bs = bs;
+ bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
+ bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);
+
+ s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
+
+ register_savevm("virtio-blk", virtio_blk_id++, 1,
+ virtio_blk_save, virtio_blk_load, s);
+
+ return s;
+}