virtio-blk: always enable VIRTIO_BLK_F_SCSI

VIRTIO_BLK_F_SCSI is supposed to mean whether the host can *parse*
SCSI requests, not *execute* them.  You could run QEMU with scsi=on
and a file-backed disk, and QEMU would fail all SCSI requests even
though it advertises VIRTIO_BLK_F_SCSI.

Because we need to do this to fix a migration compatibility problem
related to how QEMU is invoked by management, we must do this
unconditionally even on older machine types.  This more or less assumes
that no one ever invoked QEMU with scsi=off.

Here is how testing goes:

- old QEMU, scsi=on -> new QEMU, scsi=on
- new QEMU, scsi=on -> old QEMU, scsi=on
- old QEMU, scsi=off -> new QEMU, scsi=on
- new QEMU, scsi=off -> old QEMU, scsi=on
        ok (new QEMU has VIRTIO_BLK_F_SCSI, adding host features is fine)

- old QEMU, scsi=off -> new QEMU, scsi=off
        ok (new QEMU has VIRTIO_BLK_F_SCSI, adding host features is fine)

- old QEMU, scsi=on -> new QEMU, scsi=off
        ok, bug fixed

- new QEMU, scsi=on -> old QEMU, scsi=off
        doesn't work (same as: old QEMU, scsi=on -> old QEMU, scsi=off)

- new QEMU, scsi=off -> old QEMU, scsi=off
        broken by the patch

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/hw/s390-virtio-bus.c b/hw/s390-virtio-bus.c
index 43647a7a55041ad902393ca85e7a3a4b3217c088..1d38a8f5c5f3b32b1a1003ef71417954f41f87a4 100644 (file)
--- a/hw/s390-virtio-bus.c
+++ b/hw/s390-virtio-bus.c
@@ -401,6 +401,9 @@ static TypeInfo s390_virtio_net = {
 static Property s390_virtio_blk_properties[] = {
     DEFINE_BLOCK_PROPERTIES(VirtIOS390Device, blk.conf),
     DEFINE_PROP_STRING("serial", VirtIOS390Device, blk.serial),
+#ifdef __linux__
+    DEFINE_PROP_BIT("scsi", VirtIOS390Device, blk.scsi, 0, true),
+#endif
     DEFINE_PROP_END_OF_LIST(),
 };
 

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 960b9cfe3f589907b34a5476e9858a915f8f8e94..9f605d37cbbcd32c7bd056982ca65ce8682edba1 100644 (file)
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -170,7 +170,7 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
      */
     req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
 
-    if ((req->dev->vdev.guest_features & (1 << VIRTIO_BLK_F_SCSI)) == 0) {
+    if (!req->dev->blk->scsi) {
         status = VIRTIO_BLK_S_UNSUPP;
         goto fail;
     }
@@ -504,6 +504,7 @@ static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
     features |= (1 << VIRTIO_BLK_F_GEOMETRY);
     features |= (1 << VIRTIO_BLK_F_TOPOLOGY);
     features |= (1 << VIRTIO_BLK_F_BLK_SIZE);
+    features |= (1 << VIRTIO_BLK_F_SCSI);
 
     if (bdrv_enable_write_cache(s->bs))
         features |= (1 << VIRTIO_BLK_F_WCACHE);

diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
index 70564a188a3456ad901c6ead904cceb9d4769e85..d7850012bd023409628a55d9ef03fd45e6427744 100644 (file)
--- a/hw/virtio-blk.h
+++ b/hw/virtio-blk.h
@@ -101,15 +101,10 @@ struct VirtIOBlkConf
 {
     BlockConf conf;
     char *serial;
+    uint32_t scsi;
 };
 
-#ifdef __linux__
-#define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \
-        DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
-        DEFINE_PROP_BIT("scsi", _state, _field, VIRTIO_BLK_F_SCSI, true)
-#else
 #define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \
         DEFINE_VIRTIO_COMMON_FEATURES(_state, _field)
-#endif
 
 #endif

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index a20c3cf6f235672bda30d7415e456491b0760d32..79b86f1aada448613e9ace9b738f9eff689dbc92 100644 (file)
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -814,6 +814,9 @@ static Property virtio_blk_properties[] = {
     DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
     DEFINE_BLOCK_PROPERTIES(VirtIOPCIProxy, blk.conf),
     DEFINE_PROP_STRING("serial", VirtIOPCIProxy, blk.serial),
+#ifdef __linux__
+    DEFINE_PROP_BIT("scsi", VirtIOPCIProxy, blk.scsi, 0, true),
+#endif
     DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
     DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
     DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),