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. 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); *p_idx = idx; } -- 1.7.9.5 -- 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
