| Message ID | 20190124172323.230296-2-sgarzare@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-blk: add DISCARD and WRITE ZEROES features | expand |
* Stefano Garzarella (sgarzare@redhat.com) wrote: > This patch adds the support of DISCARD and WRITE ZEROES commands, > that have been introduced in the virtio-blk protocol to have > better performance when using SSD backend. > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Hi, Do you need to make those features machine-type dependent so that a VM started on a nice new qemu with this feature doesn't get confused when live migrated back to an older version? Dave > --- > hw/block/virtio-blk.c | 79 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 79 insertions(+) > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index f208c6ddb9..8850957751 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -145,6 +145,25 @@ out: > aio_context_release(blk_get_aio_context(s->conf.conf.blk)); > } > > +static void virtio_blk_discard_wzeroes_complete(void *opaque, int ret) > +{ > + VirtIOBlockReq *req = opaque; > + VirtIOBlock *s = req->dev; > + > + aio_context_acquire(blk_get_aio_context(s->conf.conf.blk)); > + if (ret) { > + if (virtio_blk_handle_rw_error(req, -ret, 0)) { > + goto out; > + } > + } > + > + virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); > + virtio_blk_free_request(req); > + > +out: > + aio_context_release(blk_get_aio_context(s->conf.conf.blk)); > +} > + > #ifdef __linux__ > > typedef struct { > @@ -584,6 +603,56 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > virtio_blk_free_request(req); > break; > } > + /* > + * VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with > + * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch statement, > + * so we must mask it for these requests, then we will check the type. > + */ > + case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT: > + case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT: > + { > + struct virtio_blk_discard_write_zeroes dwz_hdr; > + uint64_t sector; > + int bytes; > + > + if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr, > + sizeof(dwz_hdr)) != sizeof(dwz_hdr))) { > + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); > + return -1; > + } > + > + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); > + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), > + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; > + > + if (!virtio_blk_sect_range_ok(req->dev, sector, bytes)) { > + virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); > + virtio_blk_free_request(req); > + return 0; > + } > + > + if ((type & ~(VIRTIO_BLK_T_BARRIER)) == VIRTIO_BLK_T_DISCARD) { > + blk_aio_pdiscard(req->dev->blk, sector << BDRV_SECTOR_BITS, bytes, > + virtio_blk_discard_wzeroes_complete, req); > + } else if ((type & ~(VIRTIO_BLK_T_BARRIER)) == > + VIRTIO_BLK_T_WRITE_ZEROES) { > + int flags = 0; > + > + if (virtio_ldl_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.flags) & > + VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { > + flags |= BDRV_REQ_MAY_UNMAP; > + } > + > + blk_aio_pwrite_zeroes(req->dev->blk, sector << BDRV_SECTOR_BITS, > + bytes, flags, > + virtio_blk_discard_wzeroes_complete, req); > + } else { /* Unsupported if VIRTIO_BLK_T_OUT is not set */ > + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > + virtio_blk_free_request(req); > + } > + > + break; > + } > default: > virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > virtio_blk_free_request(req); > @@ -763,6 +832,14 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) > blkcfg.alignment_offset = 0; > blkcfg.wce = blk_enable_write_cache(s->blk); > virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues); > + virtio_stl_p(vdev, &blkcfg.max_discard_sectors, BDRV_REQUEST_MAX_SECTORS); > + virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1); > + virtio_stl_p(vdev, &blkcfg.discard_sector_alignment, > + blk_size >> BDRV_SECTOR_BITS); > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors, > + BDRV_REQUEST_MAX_SECTORS); > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1); > + blkcfg.write_zeroes_may_unmap = 1; > memcpy(config, &blkcfg, sizeof(struct virtio_blk_config)); > } > > @@ -787,6 +864,8 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features, > virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY); > virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY); > virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE); > + virtio_add_feature(&features, VIRTIO_BLK_F_DISCARD); > + virtio_add_feature(&features, VIRTIO_BLK_F_WRITE_ZEROES); > if (virtio_has_feature(features, VIRTIO_F_VERSION_1)) { > if (s->conf.scsi) { > error_setg(errp, "Please set scsi=off for virtio-blk devices in order to use virtio 1.0"); > -- > 2.20.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Thu, Jan 24, 2019 at 6:55 PM Dr. David Alan Gilbert <dgilbert@redhat.com> wrote: > > * Stefano Garzarella (sgarzare@redhat.com) wrote: > > This patch adds the support of DISCARD and WRITE ZEROES commands, > > that have been introduced in the virtio-blk protocol to have > > better performance when using SSD backend. > > > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > Hi, > Do you need to make those features machine-type dependent > so that a VM started on a nice new qemu with this feature doesn't > get confused when live migrated back to an older version? > Hi Dave, oh, thanks! I think the answer is absolutely yes :) I'll fix it! Another doubt that I have now is that I need to flush the MultiReqBuffer before submitting DISCARD or WRITE ZEROES commands. Thanks, Stefano
On Thu, Jan 24, 2019 at 06:23:22PM +0100, Stefano Garzarella wrote: > @@ -584,6 +603,56 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > virtio_blk_free_request(req); > break; > } > + /* > + * VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with > + * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch statement, > + * so we must mask it for these requests, then we will check the type. > + */ > + case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT: > + case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT: > + { > + struct virtio_blk_discard_write_zeroes dwz_hdr; > + uint64_t sector; > + int bytes; > + > + if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr, > + sizeof(dwz_hdr)) != sizeof(dwz_hdr))) { "The data used for discard or write zeroes command is described by one or more virtio_blk_discard_write_zeroes structs." This needs to be a loop so that multiple dwz structs can be processed up to the length of virtio_blk_req->data[]. > + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); > + return -1; > + } > + > + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); > + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), > + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; Please handle num_sectors << BDRV_SECTOR_BITS overflow so that we don't need to worry about what happens with an overflowed value later on. > + > + if (!virtio_blk_sect_range_ok(req->dev, sector, bytes)) { > + virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); > + virtio_blk_free_request(req); > + return 0; > + } > + > + if ((type & ~(VIRTIO_BLK_T_BARRIER)) == VIRTIO_BLK_T_DISCARD) { Missing device requirement: "the device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for discard commands if the unmap flag is set." > + blk_aio_pdiscard(req->dev->blk, sector << BDRV_SECTOR_BITS, bytes, > + virtio_blk_discard_wzeroes_complete, req); > + } else if ((type & ~(VIRTIO_BLK_T_BARRIER)) == > + VIRTIO_BLK_T_WRITE_ZEROES) { > + int flags = 0; > + > + if (virtio_ldl_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.flags) & > + VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { > + flags |= BDRV_REQ_MAY_UNMAP; > + } > + > + blk_aio_pwrite_zeroes(req->dev->blk, sector << BDRV_SECTOR_BITS, > + bytes, flags, > + virtio_blk_discard_wzeroes_complete, req); Please add block_acct_start(), this is treated as a write. > + } else { /* Unsupported if VIRTIO_BLK_T_OUT is not set */ > + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > + virtio_blk_free_request(req); > + } > + > + break; > + } > default: > virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > virtio_blk_free_request(req); > @@ -763,6 +832,14 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) > blkcfg.alignment_offset = 0; > blkcfg.wce = blk_enable_write_cache(s->blk); > virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues); > + virtio_stl_p(vdev, &blkcfg.max_discard_sectors, BDRV_REQUEST_MAX_SECTORS); > + virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1); > + virtio_stl_p(vdev, &blkcfg.discard_sector_alignment, > + blk_size >> BDRV_SECTOR_BITS); > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors, > + BDRV_REQUEST_MAX_SECTORS); > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1); > + blkcfg.write_zeroes_may_unmap = 1; Please check hw/scsi/scsi-disk.c for an example of how to initialize these limits. It should be possible to set some of them via s->conf so I'm surprised so many fields are hardcoded in this patch.
On Fri, Jan 25, 2019 at 02:58:56PM +0000, Stefan Hajnoczi wrote: > On Thu, Jan 24, 2019 at 06:23:22PM +0100, Stefano Garzarella wrote: > > @@ -584,6 +603,56 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > > virtio_blk_free_request(req); > > break; > > } > > + /* > > + * VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with > > + * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch statement, > > + * so we must mask it for these requests, then we will check the type. > > + */ > > + case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT: > > + case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT: > > + { > > + struct virtio_blk_discard_write_zeroes dwz_hdr; > > + uint64_t sector; > > + int bytes; > > + > > + if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr, > > + sizeof(dwz_hdr)) != sizeof(dwz_hdr))) { > > "The data used for discard or write zeroes command is described by one > or more virtio_blk_discard_write_zeroes structs." > > This needs to be a loop so that multiple dwz structs can be processed up > to the length of virtio_blk_req->data[]. > Since I set the "max_discard_seg" and "max_write_zeroes_seg" to 1, I avoided the loop, but as you suggested, making their configurable, I will add the loop. Thanks! > > + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); > > + return -1; > > + } > > + > > + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); > > + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), > > + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; > > Please handle num_sectors << BDRV_SECTOR_BITS overflow so that we don't > need to worry about what happens with an overflowed value later on. > Should I also check if num_sectors is less than "max_discard_sectors" or "max_write_zeroes_sectors"? > > + > > + if (!virtio_blk_sect_range_ok(req->dev, sector, bytes)) { > > + virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); > > + virtio_blk_free_request(req); > > + return 0; > > + } > > + > > + if ((type & ~(VIRTIO_BLK_T_BARRIER)) == VIRTIO_BLK_T_DISCARD) { > > Missing device requirement: "the device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for discard commands if the unmap flag is set." > Ooh, thanks! I'll fix it! > > + blk_aio_pdiscard(req->dev->blk, sector << BDRV_SECTOR_BITS, bytes, > > + virtio_blk_discard_wzeroes_complete, req); > > + } else if ((type & ~(VIRTIO_BLK_T_BARRIER)) == > > + VIRTIO_BLK_T_WRITE_ZEROES) { > > + int flags = 0; > > + > > + if (virtio_ldl_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.flags) & > > + VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { > > + flags |= BDRV_REQ_MAY_UNMAP; > > + } > > + > > + blk_aio_pwrite_zeroes(req->dev->blk, sector << BDRV_SECTOR_BITS, > > + bytes, flags, > > + virtio_blk_discard_wzeroes_complete, req); > > Please add block_acct_start(), this is treated as a write. > Sure! > > + } else { /* Unsupported if VIRTIO_BLK_T_OUT is not set */ > > + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > > + virtio_blk_free_request(req); > > + } > > + > > + break; > > + } > > default: > > virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); > > virtio_blk_free_request(req); > > @@ -763,6 +832,14 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) > > blkcfg.alignment_offset = 0; > > blkcfg.wce = blk_enable_write_cache(s->blk); > > virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues); > > + virtio_stl_p(vdev, &blkcfg.max_discard_sectors, BDRV_REQUEST_MAX_SECTORS); > > + virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1); > > + virtio_stl_p(vdev, &blkcfg.discard_sector_alignment, > > + blk_size >> BDRV_SECTOR_BITS); > > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors, > > + BDRV_REQUEST_MAX_SECTORS); > > + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1); > > + blkcfg.write_zeroes_may_unmap = 1; > > Please check hw/scsi/scsi-disk.c for an example of how to initialize > these limits. It should be possible to set some of them via s->conf so > I'm surprised so many fields are hardcoded in this patch. Sorry for that! I'll make some of them configurable! Last question: Do you think make sense flush the MultiReqBuffer before call blk_aio_pdiscard() or blk_aio_pwrite_zeroes()? Thanks, Stefano
On Fri, Jan 25, 2019 at 05:18:13PM +0100, Stefano Garzarella wrote: > On Fri, Jan 25, 2019 at 02:58:56PM +0000, Stefan Hajnoczi wrote: > > On Thu, Jan 24, 2019 at 06:23:22PM +0100, Stefano Garzarella wrote: > > > + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); > > > + return -1; > > > + } > > > + > > > + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); > > > + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), > > > + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; > > > > Please handle num_sectors << BDRV_SECTOR_BITS overflow so that we don't > > need to worry about what happens with an overflowed value later on. > > > > Should I also check if num_sectors is less than "max_discard_sectors" or > "max_write_zeroes_sectors"? Yes, anything that virtio_blk_sect_range_ok() doesn't check needs to be checked manually in this patch. I can't see a reason for allowing requests through that exceed the limit. > Do you think make sense flush the MultiReqBuffer before call > blk_aio_pdiscard() or blk_aio_pwrite_zeroes()? I don't think that is necessary since virtio-blk doesn't guarantee ordering (the legacy barrier feature isn't supported by QEMU). Even the MultiReqBuffer is flushed, -drive aio=threads (the default setting) could end up submitting discard/write zeroes before "earlier" requests - it depends on host kernel thread scheduler decisions. Stefan
On Sun, Jan 27, 2019 at 12:51:44PM +0000, Stefan Hajnoczi wrote: > On Fri, Jan 25, 2019 at 05:18:13PM +0100, Stefano Garzarella wrote: > > On Fri, Jan 25, 2019 at 02:58:56PM +0000, Stefan Hajnoczi wrote: > > > On Thu, Jan 24, 2019 at 06:23:22PM +0100, Stefano Garzarella wrote: > > > > + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); > > > > + return -1; > > > > + } > > > > + > > > > + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); > > > > + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), > > > > + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; > > > > > > Please handle num_sectors << BDRV_SECTOR_BITS overflow so that we don't > > > need to worry about what happens with an overflowed value later on. > > > > > > > Should I also check if num_sectors is less than "max_discard_sectors" or > > "max_write_zeroes_sectors"? > > Yes, anything that virtio_blk_sect_range_ok() doesn't check needs to be > checked manually in this patch. I can't see a reason for allowing > requests through that exceed the limit. > > > Do you think make sense flush the MultiReqBuffer before call > > blk_aio_pdiscard() or blk_aio_pwrite_zeroes()? > > I don't think that is necessary since virtio-blk doesn't guarantee > ordering (the legacy barrier feature isn't supported by QEMU). > > Even the MultiReqBuffer is flushed, -drive aio=threads (the default > setting) could end up submitting discard/write zeroes before "earlier" > requests - it depends on host kernel thread scheduler decisions. > Thanks for the details! Stefano
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index f208c6ddb9..8850957751 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -145,6 +145,25 @@ out: aio_context_release(blk_get_aio_context(s->conf.conf.blk)); } +static void virtio_blk_discard_wzeroes_complete(void *opaque, int ret) +{ + VirtIOBlockReq *req = opaque; + VirtIOBlock *s = req->dev; + + aio_context_acquire(blk_get_aio_context(s->conf.conf.blk)); + if (ret) { + if (virtio_blk_handle_rw_error(req, -ret, 0)) { + goto out; + } + } + + virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); + virtio_blk_free_request(req); + +out: + aio_context_release(blk_get_aio_context(s->conf.conf.blk)); +} + #ifdef __linux__ typedef struct { @@ -584,6 +603,56 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) virtio_blk_free_request(req); break; } + /* + * VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with + * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch statement, + * so we must mask it for these requests, then we will check the type. + */ + case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT: + case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT: + { + struct virtio_blk_discard_write_zeroes dwz_hdr; + uint64_t sector; + int bytes; + + if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr, + sizeof(dwz_hdr)) != sizeof(dwz_hdr))) { + virtio_error(vdev, "virtio-blk discard/wzeroes header too short"); + return -1; + } + + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector); + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev), + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS; + + if (!virtio_blk_sect_range_ok(req->dev, sector, bytes)) { + virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); + virtio_blk_free_request(req); + return 0; + } + + if ((type & ~(VIRTIO_BLK_T_BARRIER)) == VIRTIO_BLK_T_DISCARD) { + blk_aio_pdiscard(req->dev->blk, sector << BDRV_SECTOR_BITS, bytes, + virtio_blk_discard_wzeroes_complete, req); + } else if ((type & ~(VIRTIO_BLK_T_BARRIER)) == + VIRTIO_BLK_T_WRITE_ZEROES) { + int flags = 0; + + if (virtio_ldl_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.flags) & + VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { + flags |= BDRV_REQ_MAY_UNMAP; + } + + blk_aio_pwrite_zeroes(req->dev->blk, sector << BDRV_SECTOR_BITS, + bytes, flags, + virtio_blk_discard_wzeroes_complete, req); + } else { /* Unsupported if VIRTIO_BLK_T_OUT is not set */ + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); + virtio_blk_free_request(req); + } + + break; + } default: virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); virtio_blk_free_request(req); @@ -763,6 +832,14 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) blkcfg.alignment_offset = 0; blkcfg.wce = blk_enable_write_cache(s->blk); virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues); + virtio_stl_p(vdev, &blkcfg.max_discard_sectors, BDRV_REQUEST_MAX_SECTORS); + virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1); + virtio_stl_p(vdev, &blkcfg.discard_sector_alignment, + blk_size >> BDRV_SECTOR_BITS); + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors, + BDRV_REQUEST_MAX_SECTORS); + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1); + blkcfg.write_zeroes_may_unmap = 1; memcpy(config, &blkcfg, sizeof(struct virtio_blk_config)); } @@ -787,6 +864,8 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features, virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY); virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY); virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE); + virtio_add_feature(&features, VIRTIO_BLK_F_DISCARD); + virtio_add_feature(&features, VIRTIO_BLK_F_WRITE_ZEROES); if (virtio_has_feature(features, VIRTIO_F_VERSION_1)) { if (s->conf.scsi) { error_setg(errp, "Please set scsi=off for virtio-blk devices in order to use virtio 1.0");
This patch adds the support of DISCARD and WRITE ZEROES commands, that have been introduced in the virtio-blk protocol to have better performance when using SSD backend. Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- hw/block/virtio-blk.c | 79 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+)