Am 30.10.2015 um 13:01 schrieb Cornelia Huck:
> On Thu, 29 Oct 2015 18:09:47 -0700
> Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>
>> virtio_ring currently sends the device (usually a hypervisor)
>> physical addresses of its I/O buffers. This is okay when DMA
>> addresses and physical addresses are the same thing, but this isn't
>> always the case. For example, this never works on Xen guests, and
>> it is likely to fail if a physical "virtio" device ever ends up
>> behind an IOMMU or swiotlb.
>>
>> The immediate use case for me is to enable virtio on Xen guests.
>> For that to work, we need vring to support DMA address translation
>> as well as a corresponding change to virtio_pci or to another
>> driver.
>>
>> With this patch, if enabled, virtfs survives kmemleak and
>> CONFIG_DMA_API_DEBUG.
>>
>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
>> ---
>> drivers/virtio/Kconfig | 2 +-
>> drivers/virtio/virtio_ring.c | 190 +++++++++++++++++++++++++++++++--------
>> tools/virtio/linux/dma-mapping.h | 17 ++++
>> 3 files changed, 172 insertions(+), 37 deletions(-)
>> create mode 100644 tools/virtio/linux/dma-mapping.h
>
>> static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
>> {
>> - unsigned int i;
>> + unsigned int i, j;
>> + u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
>>
>> /* Clear data ptr. */
>> - vq->data[head] = NULL;
>> + vq->desc_state[head].data = NULL;
>>
>> - /* Put back on free list: find end */
>> + /* Put back on free list: unmap first-level descriptors and find end */
>> i = head;
>>
>> - /* Free the indirect table */
>> - if (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT))
>> - kfree(phys_to_virt(virtio64_to_cpu(vq->vq.vdev, vq->vring.desc[i].addr)));
>> -
>> - while (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT)) {
>> + while (vq->vring.desc[i].flags & nextflag) {
>> + vring_unmap_one(vq, &vq->vring.desc[i]);
>> i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
>> vq->vq.num_free++;
>> }
>>
>> + vring_unmap_one(vq, &vq->vring.desc[i]);
>> vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
>> vq->free_head = head;
>> +
>> /* Plus final descriptor */
>> vq->vq.num_free++;
>> +
>> + /* Free the indirect table, if any, now that it's unmapped. */
>> + if (vq->desc_state[head].indir_desc) {
>> + struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
>> + u32 len = vq->vring.desc[head].len;
>
> This one needs to be virtio32_to_cpu(...) as well.
Yes, just did the exact same change
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index f269e1c..f2249df 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -556,7 +556,7 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
/* Free the indirect table, if any, now that it's unmapped. */
if (vq->desc_state[head].indir_desc) {
struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
- u32 len = vq->vring.desc[head].len;
+ u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
BUG_ON(!(vq->vring.desc[head].flags &
cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
now it boots.
>
>> +
>> + BUG_ON(!(vq->vring.desc[head].flags &
>> + cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
>> + BUG_ON(len == 0 || len % sizeof(struct vring_desc));
>> +
>> + for (j = 0; j < len / sizeof(struct vring_desc); j++)
>> + vring_unmap_one(vq, &indir_desc[j]);
>> +
>> + kfree(vq->desc_state[head].indir_desc);
>> + vq->desc_state[head].indir_desc = NULL;
>> + }
>> }
>
> With that change on top of your current branch, I can boot (root on
> virtio-blk, either virtio-1 or legacy virtio) on current qemu master
> with kvm enabled on s390. Haven't tried anything further.
>
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