| Message ID | 1341321642-24598-2-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Am 03.07.2012 15:20, schrieb Paolo Bonzini: > Introduce a new feature bit and configuration field that provide > support for toggling the cache mode between writethrough and writeback. > > Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with > the spec. My spec (and my kernel as well) call it VIRTIO_BLK_F_FLUSH. What's the status of the kernel and spec side of the change? > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > hw/virtio-blk.c | 16 ++++++++++++++-- > hw/virtio-blk.h | 4 +++- > 2 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c > index fe07746..280f96d 100644 > --- a/hw/virtio-blk.c > +++ b/hw/virtio-blk.c > @@ -510,9 +510,19 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) > blkcfg.size_max = 0; > blkcfg.physical_block_exp = get_physical_block_exp(s->conf); > blkcfg.alignment_offset = 0; > + blkcfg.wce = bdrv_enable_write_cache(s->bs); > memcpy(config, &blkcfg, sizeof(struct virtio_blk_config)); > } > > +static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config) > +{ > + VirtIOBlock *s = to_virtio_blk(vdev); > + struct virtio_blk_config blkcfg; > + > + memcpy(&blkcfg, config, sizeof(blkcfg)); > + bdrv_set_enable_write_cache(s->bs, blkcfg.wce != 0); > +} We need to call bdrv_flush() here when turning WCE off. And it seems we don't have a way to signal failure, or may we just leave the bit unchanged? > @@ -49,6 +50,7 @@ struct virtio_blk_config > uint8_t alignment_offset; > uint16_t min_io_size; > uint32_t opt_io_size; > + uint8_t wce; > } QEMU_PACKED; If the spec isn't set in stone yet, we could make it a flags field instead of using a whole byte for a single flag. Kevin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Il 03/07/2012 15:46, Kevin Wolf ha scritto: >> > Introduce a new feature bit and configuration field that provide >> > support for toggling the cache mode between writethrough and writeback. >> > >> > Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with >> > the spec. > My spec (and my kernel as well) call it VIRTIO_BLK_F_FLUSH. > > What's the status of the kernel and spec side of the change? Both posted. The spec patch that introduces VIRTIO_BLK_F_CONFIG_WCE also renames it to VIRTIO_BLK_F_WCE, since that's really what it does. See this old comment in the kernel (not in the latest git anymore): /* * If the FLUSH feature is supported we do have support for * flushing a volatile write cache on the host. [...] * otherwise, we must assume that the host does not * perform any kind of volatile write caching. */ Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c index fe07746..280f96d 100644 --- a/hw/virtio-blk.c +++ b/hw/virtio-blk.c @@ -510,9 +510,19 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) blkcfg.size_max = 0; blkcfg.physical_block_exp = get_physical_block_exp(s->conf); blkcfg.alignment_offset = 0; + blkcfg.wce = bdrv_enable_write_cache(s->bs); memcpy(config, &blkcfg, sizeof(struct virtio_blk_config)); } +static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config) +{ + VirtIOBlock *s = to_virtio_blk(vdev); + struct virtio_blk_config blkcfg; + + memcpy(&blkcfg, config, sizeof(blkcfg)); + bdrv_set_enable_write_cache(s->bs, blkcfg.wce != 0); +} + static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features) { VirtIOBlock *s = to_virtio_blk(vdev); @@ -523,9 +533,10 @@ 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); + features |= (1 << VIRTIO_BLK_F_CONFIG_WCE); if (bdrv_enable_write_cache(s->bs)) - features |= (1 << VIRTIO_BLK_F_WCACHE); - + features |= (1 << VIRTIO_BLK_F_WCE); + if (bdrv_is_read_only(s->bs)) features |= 1 << VIRTIO_BLK_F_RO; @@ -615,6 +626,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk) sizeof(VirtIOBlock)); 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.reset = virtio_blk_reset; s->bs = blk->conf.bs; diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h index d785001..afea114 100644 --- a/hw/virtio-blk.h +++ b/hw/virtio-blk.h @@ -31,8 +31,9 @@ #define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/ #define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */ /* #define VIRTIO_BLK_F_IDENTIFY 8 ATA IDENTIFY supported, DEPRECATED */ -#define VIRTIO_BLK_F_WCACHE 9 /* write cache enabled */ +#define VIRTIO_BLK_F_WCE 9 /* write cache enabled */ #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */ +#define VIRTIO_BLK_F_CONFIG_WCE 11 /* write cache configurable */ #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */ @@ -49,6 +50,7 @@ struct virtio_blk_config uint8_t alignment_offset; uint16_t min_io_size; uint32_t opt_io_size; + uint8_t wce; } QEMU_PACKED; /* These two define direction. */
Introduce a new feature bit and configuration field that provide support for toggling the cache mode between writethrough and writeback. Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with the spec. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- hw/virtio-blk.c | 16 ++++++++++++++-- hw/virtio-blk.h | 4 +++- 2 files changed, 17 insertions(+), 3 deletions(-)