Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Paolo Bonzini pbonz...@redhat.com: 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. :) Uh, what a coincidence! :) 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. I never met this before. How this situation happens? 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 senw...@linux.vnet.ibm.com --- 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; Yes, I saw your another E-mail. I think you're right. Simply calling sg_set_page can not handle the flag bits correctly. So, I'll repost the patch soon. Thank you! Can you repost it with this change, and also add sta...@vger.kernel.org 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- -- Wang Sen Addr: XUPT,Xi'an,Shaanxi,China Email: kelvin.x...@gmail.com -- -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Rolf Eike Beer eike-ker...@sf-tec.de: Am 25.07.2012 10:29, schrieb Wang Sen: 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. The next sentence is somehow broken: But there are some HighMem pages in table-sgl can not get virtual address by sg_virt. Maybe something like But _if_ there are ... _you_ can not get ...? Thanks, I'll pay attention in next post. Eike -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- -- Wang Sen Addr: XUPT,Xi'an,Shaanxi,China Email: kelvin.x...@gmail.com -- -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Stefan Hajnoczi stefa...@linux.vnet.ibm.com: On Wed, Jul 25, 2012 at 10:44:14AM +0200, Paolo Bonzini wrote: 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. It's not a segfault crash, I think it hits an abort(3) in QEMU's virtio code when trying to map an invalid guest physical address. How the guest boot fail? I never met this case. Stefan -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- -- Wang Sen Addr: XUPT,Xi'an,Shaanxi,China Email: kelvin.x...@gmail.com -- -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
