[Qemu-devel] [RFC] scsi-disk: add -device scsi-disk, slow=on property

[Stefan Hajnoczi <stefanha@redhat.com>]

The 'slow' bool property simulates an 8 second delay in responding to
simple SCSI commands that do not transfer data.

This means non-READ/WRITE commands will take 8 seconds to complete so
slow SCSI LUNs can be simulated.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
This is a quick hack and probably buggy too.  Not worth merging, but I wanted
to archive it on the mailing list in case someone wants to use it for debugging
in the future.

 hw/scsi/scsi-disk.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index bada9a7..3aaa215 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -88,6 +88,9 @@ struct SCSIDiskState
     char *product;
     bool tray_open;
     bool tray_locked;
+    bool is_slow;
+    QEMUTimer *slow_timer;
+    SCSIDiskReq *slow_req;
 };
 
 static int scsi_handle_rw_error(SCSIDiskReq *r, int error);
@@ -1833,6 +1836,17 @@ static void scsi_disk_emulate_write_data(SCSIRequest *req)
     }
 }
 
+static void scsi_disk_slow_timer_cb(void *opaque)
+{
+    SCSIDiskState *s = opaque;
+    SCSIDiskReq *r = s->slow_req;
+
+    s->slow_req = NULL;
+
+    fprintf(stderr, "%s called\n", __func__);
+    scsi_req_complete(&r->req, GOOD);
+}
+
 static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
 {
     SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
@@ -2092,7 +2106,15 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
     assert(!r->req.aiocb);
     r->iov.iov_len = MIN(r->buflen, req->cmd.xfer);
     if (r->iov.iov_len == 0) {
-        scsi_req_complete(&r->req, GOOD);
+        if (s->is_slow) {
+            fprintf(stderr, "delaying scsi_req_complete...\n");
+            assert(!s->slow_req);
+            s->slow_req = r;
+            timer_mod(s->slow_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
+                                     8 * 1000ULL * 1000ULL * 1000ULL);
+        } else {
+            scsi_req_complete(&r->req, GOOD);
+        }
     }
     if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
         assert(r->iov.iov_len == req->cmd.xfer);
@@ -2335,6 +2357,9 @@ static void scsi_realize(SCSIDevice *dev, Error **errp)
     blk_set_guest_block_size(s->qdev.conf.blk, s->qdev.blocksize);
 
     blk_iostatus_enable(s->qdev.conf.blk);
+
+    s->slow_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                                 scsi_disk_slow_timer_cb, s);
 }
 
 static void scsi_hd_realize(SCSIDevice *dev, Error **errp)
@@ -2773,6 +2798,7 @@ static Property scsi_disk_properties[] = {
                        DEFAULT_MAX_UNMAP_SIZE),
     DEFINE_PROP_UINT64("max_io_size", SCSIDiskState, max_io_size,
                        DEFAULT_MAX_IO_SIZE),
+    DEFINE_PROP_BOOL("slow", SCSIDiskState, is_slow, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
-- 
2.4.3