Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Stefan Hajnoczi : > 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-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Rolf Eike Beer : > 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-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list
2012/7/25 Paolo Bonzini : > 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 >> --- >> 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-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
