From nobody Tue Nov 26 18:36:53 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1706117993; cv=none; d=zohomail.com; s=zohoarc; b=fmp3KSVED7uVdPkvqCpTv+m2XJMwdtwRnbb0F63x5RZPsViI6Mo9rSlCMpWmuejrE622Wn7wHi00EhX6HkXMk5RZseJ7POVa5IsJoFU3JZSISrvUNAUporAekXvimqcZHVarO4sJ1wicwOcSFrEIsoTZJuaSNAAUp6++ER/uqzE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1706117993; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=F4OmqxgKC3qddtr32VKeaMZ3RM6Vrl6zAhR61NVpNCM=; b=jGvFBf2rdgJI0hgY4L997zrdvfU0qf6cQNnyiCRkLe7y2TjTKqIX7ihp3HWyobE+stGz9g4O1L6Yv2VbNdc08MgS6IJbqtrSmGkDQs4SQ62g4GDpsRwAn1q43DlzinFvvvDADlrBYGRyIF0nKxpvLKw/iqKExx9hCbzP/DBs95k= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1706117993425750.7732885239762; Wed, 24 Jan 2024 09:39:53 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rShD5-00029L-IQ; Wed, 24 Jan 2024 12:38:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rShD3-00028B-KP for qemu-devel@nongnu.org; Wed, 24 Jan 2024 12:38:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rShD2-00026z-2h for qemu-devel@nongnu.org; Wed, 24 Jan 2024 12:38:45 -0500 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-301-kvcE8gPUMZuwz-zrv7iZqA-1; Wed, 24 Jan 2024 12:38:39 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3576F845DC9; Wed, 24 Jan 2024 17:38:39 +0000 (UTC) Received: from localhost (unknown [10.39.194.82]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BCDF0C0FDCA; Wed, 24 Jan 2024 17:38:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706117923; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F4OmqxgKC3qddtr32VKeaMZ3RM6Vrl6zAhR61NVpNCM=; b=SOZ/p14nmRwFi6jS8elXJlNOuV7ba79pcKy9fvRz+z8jgIZzhr8Xdm/ZP8xgeJLfRqikpq R3ZJvXuRMsrP776nUcDQ0YkBbIcTRZMB9nC/PPchm3cHygpsXLEj5YI4wB1YEb7dScQ4ZM bzU0cDTAdtkFim5Gf3WzFMhhTPQEWCk= X-MC-Unique: kvcE8gPUMZuwz-zrv7iZqA-1 From: Hanna Czenczek To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Czenczek , Stefan Hajnoczi , Fiona Ebner , Paolo Bonzini , Kevin Wolf , "Michael S . Tsirkin" , Fam Zheng Subject: [PATCH 1/2] virtio-scsi: Attach event vq notifier with no_poll Date: Wed, 24 Jan 2024 18:38:29 +0100 Message-ID: <20240124173834.66320-2-hreitz@redhat.com> In-Reply-To: <20240124173834.66320-1-hreitz@redhat.com> References: <20240124173834.66320-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 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=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.5, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: 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: 1706117995018100001 Content-Type: text/plain; charset="utf-8" As of commit 38738f7dbbda90fbc161757b7f4be35b52205552 ("virtio-scsi: don't waste CPU polling the event virtqueue"), we only attach an io_read notifier for the virtio-scsi event virtqueue instead, and no polling notifiers. During operation, the event virtqueue is typically non-empty, but none of the buffers are intended to be used immediately. Instead, they only get used when certain events occur. Therefore, it makes no sense to continuously poll it when non-empty, because it is supposed to be and stay non-empty. We do this by using virtio_queue_aio_attach_host_notifier_no_poll() instead of virtio_queue_aio_attach_host_notifier() for the event virtqueue. Commit 766aa2de0f29b657148e04599320d771c36fd126 ("virtio-scsi: implement BlockDevOps->drained_begin()") however has virtio_scsi_drained_end() use virtio_queue_aio_attach_host_notifier() for all virtqueues, including the event virtqueue. This can lead to it being polled again, undoing the benefit of commit 38738f7dbbda90fbc161757b7f4be35b52205552. Fix it by using virtio_queue_aio_attach_host_notifier_no_poll() for the event virtqueue. Reported-by: Fiona Ebner Fixes: 766aa2de0f29b657148e04599320d771c36fd126 ("virtio-scsi: implement BlockDevOps->drained_begin()") Signed-off-by: Hanna Czenczek Reviewed-by: Fiona Ebner Reviewed-by: Stefan Hajnoczi Tested-by: Fiona Ebner --- hw/scsi/virtio-scsi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 690aceec45..9f02ceea09 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -1149,6 +1149,7 @@ static void virtio_scsi_drained_begin(SCSIBus *bus) static void virtio_scsi_drained_end(SCSIBus *bus) { VirtIOSCSI *s =3D container_of(bus, VirtIOSCSI, bus); + VirtIOSCSICommon *vs =3D VIRTIO_SCSI_COMMON(s); VirtIODevice *vdev =3D VIRTIO_DEVICE(s); uint32_t total_queues =3D VIRTIO_SCSI_VQ_NUM_FIXED + s->parent_obj.conf.num_queues; @@ -1166,7 +1167,11 @@ static void virtio_scsi_drained_end(SCSIBus *bus) =20 for (uint32_t i =3D 0; i < total_queues; i++) { VirtQueue *vq =3D virtio_get_queue(vdev, i); - virtio_queue_aio_attach_host_notifier(vq, s->ctx); + if (vq =3D=3D vs->event_vq) { + virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx); + } else { + virtio_queue_aio_attach_host_notifier(vq, s->ctx); + } } } =20 --=20 2.43.0