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kvm: Fix virtio block device support some more

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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>
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:41 +01:00
committed by Will Deacon
parent 93d18b7223
commit 4155ba8cda
1 changed files with 65 additions and 43 deletions
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blk-virtio.c
+65 -43
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@@ -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;
while (queue->vring.avail->idx != queue->last_avail_idx) {
if (!blk_virtio_read(self, queue))
return false;
}
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;
}
/* 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;