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bh=v5hLZjXPLz2i52+WyQndxjGB7fi9mqlD8TwVgMsKkE4=; b=SwjqBSh3o+x3NqMEu2gXL92qbUJejme3IT6V5r20EDLrqUgwaYg6TtvyuPc/3EyzsbLmFT 11Yv9DmdiyDYpuV7aJVasW/Qh+G14PRY1J97YMi1Tm3gehE4hHorhDU+OuofKV/m50YH1m 1LpPrjklHLP42H6GmWbcw4KgdKsx0BI= X-MC-Unique: oEWy9C-dPea95u43nFg6Fg-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 16/16] virtio-blk: avoid using ioeventfd state in irqfd conditional Date: Wed, 7 Feb 2024 22:56:06 +0100 Message-ID: <20240207215606.206038-17-kwolf@redhat.com> In-Reply-To: <20240207215606.206038-1-kwolf@redhat.com> References: <20240207215606.206038-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.106, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1707343084117100007 Content-Type: text/plain; charset="utf-8" From: Stefan Hajnoczi Requests that complete in an IOThread use irqfd to notify the guest while requests that complete in the main loop thread use the traditional qdev irq code path. The reason for this conditional is that the irq code path requires the BQL: if (s->ioeventfd_started && !s->ioeventfd_disabled) { virtio_notify_irqfd(vdev, req->vq); } else { virtio_notify(vdev, req->vq); } There is a corner case where the conditional invokes the irq code path instead of the irqfd code path: static void virtio_blk_stop_ioeventfd(VirtIODevice *vdev) { ... /* * Set ->ioeventfd_started to false before draining so that host noti= fiers * are not detached/attached anymore. */ s->ioeventfd_started =3D false; /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete= */ blk_drain(s->conf.conf.blk); During blk_drain() the conditional produces the wrong result because ioeventfd_started is false. Use qemu_in_iothread() instead of checking the ioeventfd state. Buglink: https://issues.redhat.com/browse/RHEL-15394 Signed-off-by: Stefan Hajnoczi Message-ID: <20240122172625.415386-1-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/block/virtio-blk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 4ca5e632ea..738cb2ac36 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -66,7 +66,7 @@ static void virtio_blk_req_complete(VirtIOBlockReq *req, = unsigned char status) iov_discard_undo(&req->inhdr_undo); iov_discard_undo(&req->outhdr_undo); virtqueue_push(req->vq, &req->elem, req->in_len); - if (s->ioeventfd_started && !s->ioeventfd_disabled) { + if (qemu_in_iothread()) { virtio_notify_irqfd(vdev, req->vq); } else { virtio_notify(vdev, req->vq); --=20 2.43.0