[Qemu-devel] [PULL 29/29] scsi: reject configurations with logical block size > physical block size

[Paolo Bonzini]

From: Mark Kanda <address@hidden>

Logical block size of a SCSI disk should never be larger than
physical block size. From an ATA/SCSI perspective, it makes no sense
to have the logical block size greater than the physical block size,
and it cannot even be effectively expressed in the command set. The
whole point of adding the physical block size to the ATA/SCSI command
set was to communicate a desire for a larger block size (than logical),
while maintaining backwards compatibility with legacy 512 byte block
size.

When setting logical_block_size > physical_block_size, QEMU cannot express
it in READ CAPACITY(16) output, and all it can do is set the physical
block exponent to 0 (i.e. logical_block_size == physical_block_size).
Reporting the error properly, however, is better.

Signed-off-by: Mark Kanda <address@hidden>
Reviewed-by: Konrad Rzeszutek Wilk <address@hidden>
Reviewed-by: Martin K. Petersen <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 hw/scsi/scsi-disk.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index a518080..1243117 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2347,6 +2347,14 @@ static void scsi_realize(SCSIDevice *dev, Error **errp)
 
     blkconf_serial(&s->qdev.conf, &s->serial);
     blkconf_blocksizes(&s->qdev.conf);
+
+    if (s->qdev.conf.logical_block_size >
+        s->qdev.conf.physical_block_size) {
+        error_setg(errp,
+                   "logical_block_size > physical_block_size not supported");
+        return;
+    }
+
     if (dev->type == TYPE_DISK) {
         blkconf_geometry(&dev->conf, NULL, 65535, 255, 255, &err);
         if (err) {
-- 
1.8.3.1