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[Qemu-devel] [PATCH 1/1] scsi-disk.c: consider bl->max_transfer in INQUI
From: |
Daniel Henrique Barboza |
Subject: |
[Qemu-devel] [PATCH 1/1] scsi-disk.c: consider bl->max_transfer in INQUIRY emulation |
Date: |
Tue, 6 Mar 2018 12:44:11 -0300 |
The calculation of the max_transfer atribute of BlockDriverState
makes considerations such as max_segments and transfer_length via
the BLKSECTGET ioctl (if available).
However, bl->max_transfer isn't considered when emulating the INQUIRY
'Block Limit' response to the scsi-hd devices. This leads to situations
where the declared max_sectors from the INQUIRY response is inconsistent
with the block limits, which isn't ideal. It can also be misleading to the
user that sets /sys/block/<dev>/queue/max_sectors_kb to a certain
value, then finds a different value in the guest OS for the same disk.
Following the same logic scsi_read_complete from scsi-generic.c does
when patching the response of the Block Limits VPD back to the guest,
change the max_io_sectors value of the emulated Block Limits VPD
response by considering the blk_get_max_transfer of the related
BlockDriverState. Use MIN_NOT_ZERO to be sure that the minimal
value is chosen.
Given that we're changing max_io_sectors, consider that min_io_sectors
and opt_io_sectors can't be greater than the new calculated value.
Signed-off-by: Daniel Henrique Barboza <address@hidden>
---
hw/scsi/scsi-disk.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index 49d2559d93..c65c1ce56d 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -704,6 +704,21 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req,
uint8_t *outbuf)
page_code);
return -1;
}
+ if (s->qdev.type == TYPE_DISK) {
+ int max_transfer_blk = blk_get_max_transfer(s->qdev.conf.blk);
+ int max_io_sectors_blk =
+ max_transfer_blk / s->qdev.blocksize;
+
+ max_io_sectors =
+ MIN_NON_ZERO(max_io_sectors_blk, max_io_sectors);
+
+ /* 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);
+ }
/* required VPD size with unmap support */
buflen = 0x40;
memset(outbuf + 4, 0, buflen - 4);
--
2.14.3
- [Qemu-devel] [PATCH 1/1] scsi-disk.c: consider bl->max_transfer in INQUIRY emulation,
Daniel Henrique Barboza <=