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authorPaolo Bonzini <pbonzini@redhat.com>2012-08-09 16:07:20 +0200
committerKevin Wolf <kwolf@redhat.com>2012-08-10 10:25:12 +0200
commit9315cbfd8d7074eca44fbc5f93902e97b27d5240 (patch)
tree593ae6bf75d47063a3a4604cd2ea25c33c207aae
parent13e3dce068773c971ff2f19d986378c55897c4a3 (diff)
downloadqemu-arm-9315cbfd8d7074eca44fbc5f93902e97b27d5240.tar.gz
virtio-blk: disable write cache if not negotiated
If the guest does not support flushes, we should run in writethrough mode. The setting is temporary until the next reset, so that for example the BIOS will run in writethrough mode while Linux will run with a writeback cache. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--hw/virtio-blk.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 97bb4bdc7c..fd8fa90792 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -543,6 +543,19 @@ static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
return features;
}
+static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
+{
+ VirtIOBlock *s = to_virtio_blk(vdev);
+ uint32_t features;
+
+ if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+ return;
+ }
+
+ features = vdev->guest_features;
+ bdrv_set_enable_write_cache(s->bs, !!(features & (1 << VIRTIO_BLK_F_WCE)));
+}
+
static void virtio_blk_save(QEMUFile *f, void *opaque)
{
VirtIOBlock *s = opaque;
@@ -623,6 +636,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
s->vdev.get_config = virtio_blk_update_config;
s->vdev.set_config = virtio_blk_set_config;
s->vdev.get_features = virtio_blk_get_features;
+ s->vdev.set_status = virtio_blk_set_status;
s->vdev.reset = virtio_blk_reset;
s->bs = blk->conf.bs;
s->conf = &blk->conf;