From nobody Sat May 18 12:05:08 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=1674164652; cv=none; d=zohomail.com; s=zohoarc; b=k1tKXcL/XqARh+A1IJxkxcvMZNHBnED4fNjzk50X93rEY0VmsvL2OTinQ5XkNh8DgclacR7eioONK1zxLZblmoyiC/yguMOkFZGG+JU25YfksCnXxoHJFXPqrk0TUIfgSo0SzxPE2x5E+dIjYDEE1MqRPsbEoSs54GtUX+DXIzA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1674164652; h=Content-Transfer-Encoding:Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:To; bh=smz76Dr8FAhWfqUmoF4WtKoFQFPd8dl6P5HOHEHBhxs=; b=n7YvpyOm0mkRJA4D/78w1CSK9WRkSO8nqZRzCYcZuga9pGy3JTOjETR2NCnDF2ZMGZV5j9aAMgEGJrIPTBlh6PsVxbOaxtoeNAfSrkUYuya+n4CGdojv/9nFFclfDqIUdCMCzes3dUUMzvPd4w64vuoF9VqppWN2J0eEH9p8RaM= 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 1674164652099947.3693336448671; Thu, 19 Jan 2023 13:44:12 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pIch8-0003Ai-8N; Thu, 19 Jan 2023 16:43:38 -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 1pIch6-00039y-0h for qemu-devel@nongnu.org; Thu, 19 Jan 2023 16:43:36 -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 1pIch3-0002qC-GX for qemu-devel@nongnu.org; Thu, 19 Jan 2023 16:43:35 -0500 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-385-Kq81f_gVOceoNOBy3dKIgw-1; Thu, 19 Jan 2023 16:43:29 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 594B11869B6D; Thu, 19 Jan 2023 21:43:29 +0000 (UTC) Received: from localhost (unknown [10.39.194.247]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6D1FB40C2064; Thu, 19 Jan 2023 21:43:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674164612; 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; bh=smz76Dr8FAhWfqUmoF4WtKoFQFPd8dl6P5HOHEHBhxs=; b=e1Lyc10naypDR62kwvyugzolLzNdZcx/5mDyvM2lLhICueVCbBQkrkzI27o6gxdbmWSJVs p1t/RUsHgWxz7YfTZDPGOLAweAF8Bq4BlOuEt0QVytVi59eihAsbXORBlY5ydH+xRaPHPw QdUx8IZMjNdL7rPw8CC62SgOiAFtmxQ= X-MC-Unique: Kq81f_gVOceoNOBy3dKIgw-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: , Paolo Bonzini , "Michael S. Tsirkin" , Fam Zheng , Stefan Hajnoczi , Qing Wang Subject: [PATCH] virtio-scsi: reset SCSI devices from main loop thread Date: Thu, 19 Jan 2023 16:43:26 -0500 Message-Id: <20230119214326.1339323-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 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=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: 1674164652676100001 Content-Type: text/plain; charset="utf-8" When an IOThread is configured, the ctrl virtqueue is processed in the IOThread. TMFs that reset SCSI devices are currently called directly from the IOThread and trigger an assertion failure in blk_drain(): ../block/block-backend.c:1780: void blk_drain(BlockBackend *): Assertion = `qemu_in_main_thread()' failed. The blk_drain() function is not designed to be called from an IOThread because it needs the Big QEMU Lock (BQL). This patch defers TMFs that reset SCSI devices to a Bottom Half (BH) that runs in the main loop thread under the BQL. This way it's safe to call blk_drain() and the assertion failure is avoided. Introduce s->tmf_bh_list for tracking TMF requests that have been deferred to the BH. When the BH runs it will grab the entire list and process all requests. Care must be taken to clear the list when the virtio-scsi device is reset or unrealized. Otherwise deferred TMF requests could execute later and lead to use-after-free or other undefined behavior. The s->resetting counter that's used by TMFs that reset SCSI devices is accessed from multiple threads. This patch makes that explicit by using atomic accessor functions. With this patch applied the counter is only modified by the main loop thread under the BQL but can be read by any thread. Reported-by: Qing Wang Cc: Paolo Bonzini Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin --- include/hw/virtio/virtio-scsi.h | 11 ++- hw/scsi/virtio-scsi.c | 169 +++++++++++++++++++++++++------- 2 files changed, 143 insertions(+), 37 deletions(-) diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scs= i.h index 37b75e15e3..779568ab5d 100644 --- a/include/hw/virtio/virtio-scsi.h +++ b/include/hw/virtio/virtio-scsi.h @@ -74,13 +74,22 @@ struct VirtIOSCSICommon { VirtQueue **cmd_vqs; }; =20 +struct VirtIOSCSIReq; + struct VirtIOSCSI { VirtIOSCSICommon parent_obj; =20 SCSIBus bus; - int resetting; + int resetting; /* written from main loop thread, read from any thread = */ bool events_dropped; =20 + /* + * TMFs deferred to main loop BH. These fields are protected by + * virtio_scsi_acquire(). + */ + QEMUBH *tmf_bh; + QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list; + /* Fields for dataplane below */ AioContext *ctx; /* one iothread per virtio-scsi-pci for now */ =20 diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 2b649ca976..612c525d9d 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -43,13 +43,11 @@ typedef struct VirtIOSCSIReq { QEMUSGList qsgl; QEMUIOVector resp_iov; =20 - union { - /* Used for two-stage request submission */ - QTAILQ_ENTRY(VirtIOSCSIReq) next; + /* Used for two-stage request submission and TMFs deferred to BH */ + QTAILQ_ENTRY(VirtIOSCSIReq) next; =20 - /* Used for cancellation of request during TMFs */ - int remaining; - }; + /* Used for cancellation of request during TMFs */ + int remaining; =20 SCSIRequest *sreq; size_t resp_size; @@ -294,6 +292,122 @@ static inline void virtio_scsi_ctx_check(VirtIOSCSI *= s, SCSIDevice *d) } } =20 +static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req) +{ + VirtIOSCSI *s =3D req->dev; + SCSIDevice *d =3D virtio_scsi_device_get(s, req->req.tmf.lun); + BusChild *kid; + int target; + + switch (req->req.tmf.subtype) { + case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET: + if (!d) { + req->resp.tmf.response =3D VIRTIO_SCSI_S_BAD_TARGET; + goto out; + } + if (d->lun !=3D virtio_scsi_get_lun(req->req.tmf.lun)) { + req->resp.tmf.response =3D VIRTIO_SCSI_S_INCORRECT_LUN; + goto out; + } + qatomic_inc(&s->resetting); + device_cold_reset(&d->qdev); + qatomic_dec(&s->resetting); + break; + + case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET: + target =3D req->req.tmf.lun[1]; + qatomic_inc(&s->resetting); + + rcu_read_lock(); + QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) { + SCSIDevice *d1 =3D SCSI_DEVICE(kid->child); + if (d1->channel =3D=3D 0 && d1->id =3D=3D target) { + device_cold_reset(&d1->qdev); + } + } + rcu_read_unlock(); + + qatomic_dec(&s->resetting); + break; + + default: + g_assert_not_reached(); + break; + } + +out: + object_unref(OBJECT(d)); + + virtio_scsi_acquire(s); + virtio_scsi_complete_req(req); + virtio_scsi_release(s); +} + +/* Some TMFs must be processed from the main loop thread */ +static void virtio_scsi_do_tmf_bh(void *opaque) +{ + VirtIOSCSI *s =3D opaque; + QTAILQ_HEAD(, VirtIOSCSIReq) reqs =3D QTAILQ_HEAD_INITIALIZER(reqs); + VirtIOSCSIReq *req; + VirtIOSCSIReq *tmp; + + GLOBAL_STATE_CODE(); + + virtio_scsi_acquire(s); + + QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) { + QTAILQ_REMOVE(&s->tmf_bh_list, req, next); + QTAILQ_INSERT_TAIL(&reqs, req, next); + } + + qemu_bh_delete(s->tmf_bh); + s->tmf_bh =3D NULL; + + virtio_scsi_release(s); + + QTAILQ_FOREACH_SAFE(req, &reqs, next, tmp) { + QTAILQ_REMOVE(&reqs, req, next); + virtio_scsi_do_one_tmf_bh(req); + } +} + +static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s) +{ + VirtIOSCSIReq *req; + VirtIOSCSIReq *tmp; + + GLOBAL_STATE_CODE(); + + virtio_scsi_acquire(s); + + if (s->tmf_bh) { + qemu_bh_delete(s->tmf_bh); + s->tmf_bh =3D NULL; + } + + QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) { + QTAILQ_REMOVE(&s->tmf_bh_list, req, next); + + /* SAM-6 6.3.2 Hard reset */ + req->resp.tmf.response =3D VIRTIO_SCSI_S_TARGET_FAILURE; + virtio_scsi_complete_req(req); + } + + virtio_scsi_release(s); +} + +static void virtio_scsi_defer_tmf_to_bh(VirtIOSCSIReq *req) +{ + VirtIOSCSI *s =3D req->dev; + + QTAILQ_INSERT_TAIL(&s->tmf_bh_list, req, next); + + if (!s->tmf_bh) { + s->tmf_bh =3D qemu_bh_new(virtio_scsi_do_tmf_bh, s); + qemu_bh_schedule(s->tmf_bh); + } +} + /* Return 0 if the request is ready to be completed and return to guest; * -EINPROGRESS if the request is submitted and will be completed later, i= n the * case of async cancellation. */ @@ -301,8 +415,6 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSI= Req *req) { SCSIDevice *d =3D virtio_scsi_device_get(s, req->req.tmf.lun); SCSIRequest *r, *next; - BusChild *kid; - int target; int ret =3D 0; =20 virtio_scsi_ctx_check(s, d); @@ -359,15 +471,9 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCS= IReq *req) break; =20 case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET: - if (!d) { - goto fail; - } - if (d->lun !=3D virtio_scsi_get_lun(req->req.tmf.lun)) { - goto incorrect_lun; - } - s->resetting++; - device_cold_reset(&d->qdev); - s->resetting--; + case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET: + virtio_scsi_defer_tmf_to_bh(req); + ret =3D -EINPROGRESS; break; =20 case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET: @@ -410,22 +516,6 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCS= IReq *req) } break; =20 - case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET: - target =3D req->req.tmf.lun[1]; - s->resetting++; - - rcu_read_lock(); - QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) { - SCSIDevice *d1 =3D SCSI_DEVICE(kid->child); - if (d1->channel =3D=3D 0 && d1->id =3D=3D target) { - device_cold_reset(&d1->qdev); - } - } - rcu_read_unlock(); - - s->resetting--; - break; - case VIRTIO_SCSI_T_TMF_CLEAR_ACA: default: req->resp.tmf.response =3D VIRTIO_SCSI_S_FUNCTION_REJECTED; @@ -655,7 +745,7 @@ static void virtio_scsi_request_cancelled(SCSIRequest *= r) if (!req) { return; } - if (req->dev->resetting) { + if (qatomic_read(&req->dev->resetting)) { req->resp.cmd.response =3D VIRTIO_SCSI_S_RESET; } else { req->resp.cmd.response =3D VIRTIO_SCSI_S_ABORTED; @@ -831,9 +921,12 @@ static void virtio_scsi_reset(VirtIODevice *vdev) VirtIOSCSICommon *vs =3D VIRTIO_SCSI_COMMON(vdev); =20 assert(!s->dataplane_started); - s->resetting++; + + virtio_scsi_reset_tmf_bh(s); + + qatomic_inc(&s->resetting); bus_cold_reset(BUS(&s->bus)); - s->resetting--; + qatomic_dec(&s->resetting); =20 vs->sense_size =3D VIRTIO_SCSI_SENSE_DEFAULT_SIZE; vs->cdb_size =3D VIRTIO_SCSI_CDB_DEFAULT_SIZE; @@ -1053,6 +1146,8 @@ static void virtio_scsi_device_realize(DeviceState *d= ev, Error **errp) VirtIOSCSI *s =3D VIRTIO_SCSI(dev); Error *err =3D NULL; =20 + QTAILQ_INIT(&s->tmf_bh_list); + virtio_scsi_common_realize(dev, virtio_scsi_handle_ctrl, virtio_scsi_handle_event, @@ -1090,6 +1185,8 @@ static void virtio_scsi_device_unrealize(DeviceState = *dev) { VirtIOSCSI *s =3D VIRTIO_SCSI(dev); =20 + virtio_scsi_reset_tmf_bh(s); + qbus_set_hotplug_handler(BUS(&s->bus), NULL); virtio_scsi_common_unrealize(dev); } --=20 2.39.0