kvm: Fix virtio block device support some more

This patch fixes the following issues in virtio block device support:

- Handle all requests in the virtqueue before signaling an interrupt.

- Initialize ->used vring elements properly.

- Handle non-read requests by injecting an I/O error to the guest.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/blk-virtio.c b/tools/kvm/blk-virtio.c
index a99738e2d388344c9f68ad5d685f38396e5ceaec..ef197e6fe9397b51684c4261ed8b6bf5145d4bb5 100644 (file)
--- a/tools/kvm/blk-virtio.c
+++ b/tools/kvm/blk-virtio.c
@@ -9,6 +9,9 @@
 #include "kvm/kvm.h"
 #include "kvm/pci.h"
 
+#include <inttypes.h>
+#include <assert.h>
+
 #define VIRTIO_BLK_IRQ         14
 
 #define NUM_VIRT_QUEUES                1
@@ -110,6 +113,65 @@ static bool blk_virtio_in(struct kvm *self, uint16_t port, void *data, int size,
        return true;
 }
 
+static bool blk_virtio_read(struct kvm *self, struct virt_queue *queue)
+{
+       struct vring_used_elem *used_elem;
+       struct virtio_blk_outhdr *req;
+       struct vring_desc *desc;
+       uint16_t desc_ndx;
+       uint32_t dst_len;
+       uint8_t *status;
+       void *dst;
+       int err;
+
+       desc_ndx                = queue->vring.avail->ring[queue->last_avail_idx++ % queue->vring.num];
+
+       if (desc_ndx >= queue->vring.num) {
+               warning("fatal I/O error");
+               return false;
+       }
+
+       /* header */
+       desc                    = &queue->vring.desc[desc_ndx];
+       assert(!(desc->flags & VRING_DESC_F_INDIRECT));
+
+       req                     = guest_flat_to_host(self, desc->addr);
+
+       /* block */
+       desc                    = &queue->vring.desc[desc->next];
+       assert(!(desc->flags & VRING_DESC_F_INDIRECT));
+
+       dst                     = guest_flat_to_host(self, desc->addr);
+       dst_len                 = desc->len;
+
+       /* status */
+       desc                    = &queue->vring.desc[desc->next];
+       assert(!(desc->flags & VRING_DESC_F_INDIRECT));
+
+       status                  = guest_flat_to_host(self, desc->addr);
+
+       info("reading sector %" PRIu64 " (%d bytes)", req->sector, dst_len);
+
+       if (req->type == VIRTIO_BLK_T_IN) {
+               err = disk_image__read_sector(self->disk_image, req->sector, dst, dst_len);
+
+               if (err)
+                       *status                 = VIRTIO_BLK_S_IOERR;
+               else
+                       *status                 = VIRTIO_BLK_S_OK;
+       } else {
+               warning("request type %d", req->type);
+               *status                 = VIRTIO_BLK_S_IOERR;
+       }
+
+       used_elem               = &queue->vring.used->ring[queue->vring.used->idx++ % queue->vring.num];
+
+       used_elem->id           = desc_ndx;
+       used_elem->len          = 3;
+
+       return true;
+}
+
 static bool blk_virtio_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
 {
        unsigned long offset;
@@ -138,57 +200,17 @@ static bool blk_virtio_out(struct kvm *self, uint16_t port, void *data, int size
                device.queue_selector   = ioport__read16(data);
                break;
        case VIRTIO_PCI_QUEUE_NOTIFY: {
-               struct virtio_blk_outhdr *req;
                struct virt_queue *queue;
-               struct vring_desc *desc;
                uint16_t queue_index;
-               uint16_t desc_ndx;
-               uint32_t dst_len;
-               uint8_t *status;
-               void *dst;
-               int err;
 
                queue_index             = ioport__read16(data);
 
                queue                   = &device.virt_queues[queue_index];
 
-               if (queue->vring.avail->idx == queue->last_avail_idx) {
-                       warning("vring is empty");
-                       break;
-               }
-
-               desc_ndx                = queue->vring.avail->ring[queue->last_avail_idx++ % queue->vring.num];
-
-               if (desc_ndx >= queue->vring.num) {
-                       warning("fatal I/O error");
-                       break;
+               while (queue->vring.avail->idx != queue->last_avail_idx) {
+                       if (!blk_virtio_read(self, queue))
+                               return false;
                }
-
-               /* header */
-               desc                    = &queue->vring.desc[desc_ndx];
-
-               req                     = guest_flat_to_host(self, desc->addr);
-
-               /* block */
-               desc                    = &queue->vring.desc[desc->next];
-
-               dst                     = guest_flat_to_host(self, desc->addr);
-               dst_len                 = desc->len;
-
-               /* status */
-               desc                    = &queue->vring.desc[desc->next];
-
-               status                  = guest_flat_to_host(self, desc->addr);
-
-               err = disk_image__read_sector(self->disk_image, req->sector, dst, dst_len);
-
-               if (err)
-                       *status                 = VIRTIO_BLK_S_IOERR;
-               else
-                       *status                 = VIRTIO_BLK_S_OK;
-
-               queue->vring.used->idx++;
-
                kvm__irq_line(self, VIRTIO_BLK_IRQ, 1);
 
                break;