Il 25/07/2012 10:29, Wang Sen ha scritto: > 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 there are some HighMem pages in > table->sgl 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. Heh, I was compiling (almost) the same patch as we speak. :) I've never seen QEMU crash; the VM would more likely just fail to boot with a panic. But it's the same bug anyway. > My solution is using sg_set_page instead of sg_set_buf. > > I have tested the patch on my workstation. QEMU would not crash any more. > > Signed-off-by: Wang Sen <senwang@xxxxxxxxxxxxxxxxxx> > --- > drivers/scsi/virtio_scsi.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c > index 1b38431..fc5c88a 100644 > --- a/drivers/scsi/virtio_scsi.c > +++ b/drivers/scsi/virtio_scsi.c > @@ -198,7 +198,8 @@ 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_set_page(&sg[idx++], sg_page(sg_elem), sg_elem->length, > + sg_elem->offset); This can simply be sg[idx++] = *sg_elem; Can you repost it with this change, and also add stable@xxxxxxxxxxxxxxx to the Cc? Thanks very much! Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
