55 lines
2.2 KiB
Diff
55 lines
2.2 KiB
Diff
From: Wang Sen <senwang@linux.vnet.ibm.com>
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Date: Mon, 30 Jul 2012 14:25:06 +0800
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Subject: [09/12] [SCSI] scsi: virtio-scsi: Fix address translation failure of
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HighMem pages used by sg list
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commit 27e99ade81368e6fdda3212bff9345177cf9e57a upstream.
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When using the commands below to write some data to a virtio-scsi LUN of the
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QEMU guest(32-bit) with 1G physical memory(qemu -m 1024), the qemu will crash.
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# sudo mkfs.ext4 /dev/sdb (/dev/sdb is the virtio-scsi LUN.)
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# sudo mount /dev/sdb /mnt
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# dd if=/dev/zero of=/mnt/file bs=1M count=1024
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In current implementation, sg_set_buf is called to add buffers to sg list which
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is put into the virtqueue eventually. But if there are some HighMem pages in
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table->sgl you can not get virtual address by sg_virt. So, sg_virt(sg_elem) may
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return NULL value. This will cause QEMU exit when virtqueue_map_sg is called
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in QEMU because an invalid GPA is passed by virtqueue.
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Two solutions are discussed here:
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http://lkml.indiana.edu/hypermail/linux/kernel/1207.3/00675.html
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Finally, value assignment approach was adopted because:
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Value assignment creates a well-formed scatterlist, because the termination
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marker in source sg_list has been set in blk_rq_map_sg(). The last entry of the
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source sg_list is just copied to the the last entry in destination list. Note
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that, for now, virtio_ring does not care about the form of the scatterlist and
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simply processes the first out_num + in_num consecutive elements of the sg[]
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array.
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I have tested the patch on my workstation. QEMU would not crash any more.
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Signed-off-by: Wang Sen <senwang@linux.vnet.ibm.com>
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Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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---
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drivers/scsi/virtio_scsi.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
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index c7030fb..3e79a2f 100644
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--- a/drivers/scsi/virtio_scsi.c
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+++ b/drivers/scsi/virtio_scsi.c
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@@ -331,7 +331,7 @@ static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx,
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int i;
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for_each_sg(table->sgl, sg_elem, table->nents, i)
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- sg_set_buf(&sg[idx++], sg_virt(sg_elem), sg_elem->length);
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+ sg[idx++] = *sg_elem;
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*p_idx = idx;
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}
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