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author | Wang Sen <senwang@linux.vnet.ibm.com> | 2012-07-30 06:25:06 (GMT) |
---|---|---|
committer | James Bottomley <JBottomley@Parallels.com> | 2012-09-14 14:47:01 (GMT) |
commit | 27e99ade81368e6fdda3212bff9345177cf9e57a (patch) | |
tree | 79b4dcafc7860c5d9e0817b321e127eb0ff4415d | |
parent | 0bd1189e239c76eb3a50e458548fbe7e4a5dfff1 (diff) | |
download | linux-27e99ade81368e6fdda3212bff9345177cf9e57a.tar.xz |
[SCSI] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
When using the commands below to write some data to a virtio-scsi LUN of the
QEMU guest(32-bit) with 1G physical memory(qemu -m 1024), the qemu will crash.
# sudo mkfs.ext4 /dev/sdb (/dev/sdb is the virtio-scsi LUN.)
# sudo mount /dev/sdb /mnt
# dd if=/dev/zero of=/mnt/file bs=1M count=1024
In current implementation, sg_set_buf is called to add buffers to sg list which
is put into the virtqueue eventually. But if there are some HighMem pages in
table->sgl you can not get virtual address by sg_virt. So, sg_virt(sg_elem) may
return NULL value. This will cause QEMU exit when virtqueue_map_sg is called
in QEMU because an invalid GPA is passed by virtqueue.
Two solutions are discussed here:
http://lkml.indiana.edu/hypermail/linux/kernel/1207.3/00675.html
Finally, value assignment approach was adopted because:
Value assignment creates a well-formed scatterlist, because the termination
marker in source sg_list has been set in blk_rq_map_sg(). The last entry of the
source sg_list is just copied to the the last entry in destination list. Note
that, for now, virtio_ring does not care about the form of the scatterlist and
simply processes the first out_num + in_num consecutive elements of the sg[]
array.
I have tested the patch on my workstation. QEMU would not crash any more.
Cc: <stable@vger.kernel.org> # 3.4: 4fe74b1: [SCSI] virtio-scsi: SCSI driver
Signed-off-by: Wang Sen <senwang@linux.vnet.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
-rw-r--r-- | drivers/scsi/virtio_scsi.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index c7030fb..3e79a2f 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -331,7 +331,7 @@ static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx, int i; for_each_sg(table->sgl, sg_elem, table->nents, i) - sg_set_buf(&sg[idx++], sg_virt(sg_elem), sg_elem->length); + sg[idx++] = *sg_elem; *p_idx = idx; } |