From 9315cbfd8d7074eca44fbc5f93902e97b27d5240 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 9 Aug 2012 16:07:20 +0200 Subject: [PATCH] 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 Signed-off-by: Kevin Wolf --- hw/virtio-blk.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) 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;