Hi,
On 03/22/2018 04:38 AM, Fam Zheng wrote:
Some backends report big max_io_sectors. Making min_io_size the same
value in this case will make it impossible for guest to align memory,
therefore the disk may not be usable at all.
Change the default behavior (when min_io_size and opt_io_size are not
specified in the command line), do not assume max_io_sectors is a good
value for opt_io_size and min_io_size, use 512 instead.
Reported-by: David Gibson <dgib...@redhat.com>
Signed-off-by: Fam Zheng <f...@redhat.com>
---
hw/scsi/scsi-disk.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index 5b7a48f5a5..76e3c9eaa4 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -714,10 +714,8 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req,
uint8_t *outbuf)
/* min_io_size and opt_io_size can't be greater than
* max_io_sectors */
- min_io_size =
- MIN_NON_ZERO(min_io_size, max_io_sectors);
- opt_io_size =
- MIN_NON_ZERO(opt_io_size, max_io_sectors);
+ min_io_size = MIN(min_io_size ? : 512, max_io_sectors);
+ opt_io_size = MIN(opt_io_size ? : 512, max_io_sectors);
}
This code you're changing was added in d082d16a5c ("consider
bl->max_transfer ..").
I've borrowed this logic from scsi-generic.c, scsi_read_complete:
if (s->type == TYPE_DISK &&
r->req.cmd.buf[0] == INQUIRY &&
r->req.cmd.buf[2] == 0xb0) {
uint32_t max_transfer =
blk_get_max_transfer(s->conf.blk) / s->blocksize;
assert(max_transfer);
stl_be_p(&r->buf[8], max_transfer);
/* Also take care of the opt xfer len. */
stl_be_p(&r->buf[12],
MIN_NON_ZERO(max_transfer, ldl_be_p(&r->buf[12])));
}
Unless I've misunderstood the bug, you will want to change this code
too. Otherwise
you'll fix it with emulated disks but it might appear when using SCSI
passthrough.
Thanks,
Daniel
/* required VPD size with unmap support */
buflen = 0x40;
