From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 915ABC624D6 for ; Thu, 3 Sep 2026 00:51:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x1vfb-0005jF-Au; Wed, 02 Sep 2026 20:51:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x1vfa-0005j2-DN; Wed, 02 Sep 2026 20:51:10 -0400 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x1vfY-0003kU-Iw; Wed, 02 Sep 2026 20:51:10 -0400 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 7F719600C8; Thu, 3 Sep 2026 00:51:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A7391F000E9; Thu, 3 Sep 2026 00:51:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788396664; bh=w7iDhP3JuhfOEvI4XVt3STgNBMKWPsP6voQdbRPD86A=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=IkpzB+uV0R+g0N2P9rA93tOLkO+8Sh6RHRtg+L3i2DYciYqAlQYI4InZB3Yvth3au lEosvw6sR2qKIRGgvOU2Ab0GoqGg3pFxa1pFCvTcITIIOvvCjZEwo3R6txnmReRnrK JTRQftA0QYeWTdtul6yC2KxyY8zNBra1rEsE0NIs9VUxPyPv5533nFM0J0VlIRtMRH Cm9zUpgETpLIJiRbyz5Ky2O6OIj4VwtV5llA6MVTR4gkrP6X7DvbiSoXzsY2spA8pB esgKhKRWPY+u5d9/8Am4Ebteryz5ucaC7DIUKTf4ie40wkqzG3nLFCYQNrG1EEFcNx Uce01Js0A5EnA== Message-ID: Date: Thu, 3 Sep 2026 09:51:01 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 04/11] virtio-blk: check the write granularity of writes to sequential zones To: Niklas Cassel , Stefan Hajnoczi , Kevin Wolf , "Michael S. Tsirkin" , Hanna Reitz Cc: Sam Li , qemu-block@nongnu.org, qemu-devel@nongnu.org References: <20260902194423.759355-1-cassel@kernel.org> <20260902194423.759355-5-cassel@kernel.org> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20260902194423.759355-5-cassel@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2600:3c04:e001:324:0:1991:8:25; envelope-from=dlemoal@kernel.org; helo=tor.source.kernel.org X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/3/26 04:44, Niklas Cassel wrote: > All VIRTIO_BLK_T_OUT requests issued to sequential zones and all > VIRTIO_BLK_T_ZONE_APPEND requests must have an offset and a data size > that are multiples of the write granularity reported by the device > (virtio 1.4, 5.2.6.1), and a violation is reported as > VIRTIO_BLK_S_ZONE_UNALIGNED_WP (virtio 1.4, 5.2.6). > > Neither request type was fully checked. Zone appends validated only the > offset, while writes were not checked at all. > > Check the size of the appended data, and both the offset and the size of > a write, against blkconf_zone_write_granularity(), so that every request the > device accepts is one that the guest driver was told is valid. Writes to > conventional zones keep no alignment constraint beyond the logical block > size. The write path performs the check after virtio_blk_sect_range_ok() > so that the zone index derived from the guest supplied sector is known to > be in range. > > Signed-off-by: Niklas Cassel > --- > hw/block/virtio-blk.c | 37 ++++++++++++++++++++++++++++++++++++- > 1 file changed, 36 insertions(+), 1 deletion(-) > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index b22aed04a1..247af53ae2 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -398,6 +398,32 @@ static bool virtio_blk_sect_range_ok(VirtIOBlock *dev, > return true; > } > > +/* > + * Both the offset and the size of a write to a sequential zone must be a > + * multiple of the write granularity that the device reports. Conventional > + * zones are not constrained. The zone index is derived from a guest supplied > + * sector, so this must only be called once virtio_blk_sect_range_ok() has > + * bounded it. > + */ > +static bool virtio_blk_zone_write_granularity_ok(VirtIOBlock *dev, > + uint64_t sector, size_t size) > +{ > + BlockDriverState *bs = blk_bs(dev->blk); > + uint64_t offset = sector << BDRV_SECTOR_BITS; > + uint32_t wg_mask; > + > + if (bs->bl.zoned == BLK_Z_NONE) { > + return true; > + } > + > + wg_mask = blkconf_zone_write_granularity(&dev->conf.conf) - 1; > + if (!(offset & wg_mask) && !(size & wg_mask)) { > + return true; > + } > + > + return BDRV_ZT_IS_CONV(bs->wps->wp[offset / bs->bl.zone_size]); > +} Even though in practice I do not think it would ever happen, technically, conventional zones are not bound by the physical sector size/write granularity and can accept LBA aligned writes even when LBA size < physical block size (write granularity). SO I think this should be: +static bool virtio_blk_zone_write_granularity_ok(VirtIOBlock *dev, + uint64_t sector, size_t size) +{ + BlockDriverState *bs = blk_bs(dev->blk); + uint64_t offset = sector << BDRV_SECTOR_BITS; + uint32_t wg_mask; + + if (bs->bl.zoned == BLK_Z_NONE) { + return true; + } + + if (BDRV_ZT_IS_CONV(bs->wps->wp[offset / bs->bl.zone_size]) { + return true; + } + + wg_mask = blkconf_zone_write_granularity(&dev->conf.conf) - 1; + return !(offset & wg_mask) && !(size & wg_mask); +} Side note not for this patch: it really would be nice to have a helper that gives a zone number from an offset, using a bit shift (bs->bl.zone_size_shift) instead of a costly division. > + > static uint8_t virtio_blk_handle_discard_write_zeroes(VirtIOBlockReq *req, > struct virtio_blk_discard_write_zeroes *dwz_hdr, bool is_write_zeroes) > { > @@ -522,7 +548,7 @@ static bool check_zoned_request(VirtIOBlock *s, int64_t offset, int64_t len, > if (append) { > uint32_t wg_mask = blkconf_zone_write_granularity(&s->conf.conf) - 1; > > - if (offset & wg_mask) { > + if (offset & wg_mask || len & wg_mask) { > *status = VIRTIO_BLK_S_ZONE_UNALIGNED_WP; > return false; > } > @@ -911,6 +937,15 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > return 0; > } > > + if (is_write && > + !virtio_blk_zone_write_granularity_ok(s, req->sector_num, > + req->qiov.size)) { > + virtio_blk_req_complete(req, VIRTIO_BLK_S_ZONE_UNALIGNED_WP); > + block_acct_invalid(blk_get_stats(s->blk), BLOCK_ACCT_WRITE); > + g_free(req); > + return 0; > + } > + > block_acct_start(blk_get_stats(s->blk), &req->acct, req->qiov.size, > is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ); > -- Damien Le Moal Western Digital Research