scsi-disk: fix VERIFY emulation

VERIFY emulation was completely botched (and remained botched through
all the refactorings).  The command must be emulated both in check-medium
mode (BYTCHK=00, which we implement by doing nothing) and in check-bytes
mode (which we do not implement yet).  Unlike WRITE AND VERIFY (which we
treat simply as WRITE with FUA bit set), VERIFY cannot be handled like
READ.  In fact the device is _receiving_ data for VERIFY, not _sending_
it like READ.

Cc: qemu-stable@nongnu.org
Tested-by: NHervé Poussineau <hpoussin@reactos.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-disk.c

@@ -1720,10 +1720,19 @@ static void scsi_disk_emulate_write_data(SCSIRequest *req)
         scsi_disk_emulate_unmap(r, r->iov.iov_base);
         break;
 
+    case VERIFY_10:
+    case VERIFY_12:
+    case VERIFY_16:
+        if (r->req.status == -1) {
+            scsi_check_condition(r, SENSE_CODE(INVALID_FIELD));
+        }
+        break;
+
     case WRITE_SAME_10:
     case WRITE_SAME_16:
         scsi_disk_emulate_write_same(r, r->iov.iov_base);
         break;
+
     default:
         abort();
     }
@@ -1964,6 +1973,14 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
     case UNMAP:
         DPRINTF("Unmap (len %lu)\n", (long)r->req.cmd.xfer);
         break;
+    case VERIFY_10:
+    case VERIFY_12:
+    case VERIFY_16:
+        DPRINTF("Verify (bytchk %lu)\n", (r->req.buf[1] >> 1) & 3);
+        if (req->cmd.buf[1] & 6) {
+            goto illegal_request;
+        }
+        break;
     case WRITE_SAME_10:
     case WRITE_SAME_16:
         DPRINTF("WRITE SAME %d (len %lu)\n",
@@ -2044,10 +2061,6 @@ static int32_t scsi_disk_dma_command(SCSIRequest *req, uint8_t *buf)
             scsi_check_condition(r, SENSE_CODE(WRITE_PROTECTED));
             return 0;
         }
-        /* fallthrough */
-    case VERIFY_10:
-    case VERIFY_12:
-    case VERIFY_16:
         DPRINTF("Write %s(sector %" PRId64 ", count %u)\n",
                 (command & 0xe) == 0xe ? "And Verify " : "",
                 r->req.cmd.lba, len);
@@ -2315,14 +2328,14 @@ static const SCSIReqOps *const scsi_disk_reqops_dispatch[256] = {
     [UNMAP]                           = &scsi_disk_emulate_reqops,
     [WRITE_SAME_10]                   = &scsi_disk_emulate_reqops,
     [WRITE_SAME_16]                   = &scsi_disk_emulate_reqops,
+    [VERIFY_10]                       = &scsi_disk_emulate_reqops,
+    [VERIFY_12]                       = &scsi_disk_emulate_reqops,
+    [VERIFY_16]                       = &scsi_disk_emulate_reqops,
 
     [READ_6]                          = &scsi_disk_dma_reqops,
     [READ_10]                         = &scsi_disk_dma_reqops,
     [READ_12]                         = &scsi_disk_dma_reqops,
     [READ_16]                         = &scsi_disk_dma_reqops,
-    [VERIFY_10]                       = &scsi_disk_dma_reqops,
-    [VERIFY_12]                       = &scsi_disk_dma_reqops,
-    [VERIFY_16]                       = &scsi_disk_dma_reqops,
     [WRITE_6]                         = &scsi_disk_dma_reqops,
     [WRITE_10]                        = &scsi_disk_dma_reqops,
     [WRITE_12]                        = &scsi_disk_dma_reqops,