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authorWang Sen <senwang@linux.vnet.ibm.com>2012-07-30 14:25:06 +0800
committerJames Bottomley <JBottomley@Parallels.com>2012-09-14 15:47:01 +0100
commit27e99ade81368e6fdda3212bff9345177cf9e57a (patch)
tree79b4dcafc7860c5d9e0817b321e127eb0ff4415d /drivers/scsi/virtio_scsi.c
parent0bd1189e239c76eb3a50e458548fbe7e4a5dfff1 (diff)
downloadlinux-27e99ade81368e6fdda3212bff9345177cf9e57a.tar.bz2
[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>
Diffstat (limited to 'drivers/scsi/virtio_scsi.c')
-rw-r--r--drivers/scsi/virtio_scsi.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index c7030fbee79c..3e79a2f00042 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;
}