[Qemu-devel] [PATCH 10/18] virtio-blk: restore VirtIOBlkConf->config_wce flag

[Stefan Hajnoczi <stefanha@redhat.com>]

Two slightly different versions of a patch to conditionally set
VIRTIO_BLK_F_CONFIG_WCE through the "config-wce" qdev property have been
applied (ea776abca and eec7f96c2).  David Gibson
<david@gibson.dropbear.id.au> noticed that the "config-wce"
property is broken as a result and fixed it recently.

The fix sets the host_features VIRTIO_BLK_F_CONFIG_WCE bit from a qdev
property.  Unfortunately, the virtio device then has no chance to test
for the presence of the feature bit during virtio_blk_init().

Therefore, reinstate the VirtIOBlkConf->config_wce flag.  Drop the
duplicate qdev property to set the host_features bit.  The
VirtIOBlkConf->config_wce flag will be used by virtio-blk-data-plane in
a later patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/virtio-blk.c | 3 +++
 hw/virtio-blk.h | 4 ++--
 hw/virtio-pci.c | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index e25cc96..fabf387 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -524,6 +524,9 @@ static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
     features |= (1 << VIRTIO_BLK_F_BLK_SIZE);
     features |= (1 << VIRTIO_BLK_F_SCSI);
 
+    if (s->blk->config_wce) {
+        features |= (1 << VIRTIO_BLK_F_CONFIG_WCE);
+    }
     if (bdrv_enable_write_cache(s->bs))
         features |= (1 << VIRTIO_BLK_F_WCE);
 
diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
index 651a000..454f445 100644
--- a/hw/virtio-blk.h
+++ b/hw/virtio-blk.h
@@ -104,10 +104,10 @@ struct VirtIOBlkConf
     BlockConf conf;
     char *serial;
     uint32_t scsi;
+    uint32_t config_wce;
 };
 
 #define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \
-        DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
-        DEFINE_PROP_BIT("config-wce", _state, _field, VIRTIO_BLK_F_CONFIG_WCE, true)
+        DEFINE_VIRTIO_COMMON_FEATURES(_state, _field)
 
 #endif
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 7684ac9..71f4fb5 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -895,6 +895,7 @@ static Property virtio_blk_properties[] = {
 #ifdef __linux__
     DEFINE_PROP_BIT("scsi", VirtIOPCIProxy, blk.scsi, 0, true),
 #endif
+    DEFINE_PROP_BIT("config-wce", VirtIOPCIProxy, blk.config_wce, 0, true),
     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),
-- 
1.8.0.2