From patchwork Thu Sep 16 10:33:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cristian Marussi X-Patchwork-Id: 12498643 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 752FFC433EF for ; Thu, 16 Sep 2021 10:37:51 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2DD5C61108 for ; Thu, 16 Sep 2021 10:37:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2DD5C61108 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vIx4v1JMpHXrJY33wLiy89VoS4P8idQD0aQI0zsgFHw=; b=ZwfoT+UVel0v0V Djfs9oKDJzbUgMu3gY1BrzlZmo4Hk/c6QV5ktQeETBZRV/OS3i8Wl2fvW3KQAuk3c3Ji52FB89x2b IrrsSJSB0AXMrESWbKPV2Sr8QJm2ZNR2RTOG4LNBC1b2ANPq5MmJsbYGGGVyz2OiBGgPg6tkIZxrZ mOCiaHGD5AKSn8kdqtphFVklVWdupeyWjfX6ALwzFS5Jog/q0swHiEF7c05GOJsFb1udfhy6mInhu 6eUbslbiMecJsuFisoEZTPv4WRCf134BYQ3D4GE+TcQUnRbxQhyGMNBbFkHoUrBZ4+d9Ecr3h91lt RBBePXZUOjA5PhxEltpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQojE-00Aqhm-V5; Thu, 16 Sep 2021 10:34:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQoiu-00AqgB-56 for linux-arm-kernel@lists.infradead.org; Thu, 16 Sep 2021 10:34:33 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 08DF01063; Thu, 16 Sep 2021 03:34:29 -0700 (PDT) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 69F7C3F5A1; Thu, 16 Sep 2021 03:34:25 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com, cristian.marussi@arm.com, igor.skalkin@opensynergy.com, peter.hilber@opensynergy.com, alex.bennee@linaro.org, jean-philippe@linaro.org, mikhail.golubev@opensynergy.com, anton.yakovlev@opensynergy.com, Vasyl.Vavrychuk@opensynergy.com, Tryshnivskyy@opensynergy.com, "Michael S. Tsirkin" Subject: [PATCH 3/3] firmware: arm_scmi: Add proper barriers to scmi virtio device Date: Thu, 16 Sep 2021 11:33:36 +0100 Message-Id: <20210916103336.7243-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210916103336.7243-1-cristian.marussi@arm.com> References: <20210916103336.7243-1-cristian.marussi@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210916_033432_302902_3CF9AF93 X-CRM114-Status: GOOD ( 14.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Only one single SCMI Virtio device is currently supported by this driver and it is referenced using a static global variable which is initialized once for all during probing and nullified at virtio device removal. Add proper SMP barriers to protect accesses to such device reference to ensure that the initialzation state of such device is correctly observed by all PEs at any time. Return -EBUSY, instead of -EINVAL, and a descriptive error message if more than one SCMI Virtio device is ever found and probed. Cc: "Michael S. Tsirkin" Cc: Sudeep Holla Signed-off-by: Cristian Marussi --- drivers/firmware/arm_scmi/virtio.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c index 633b5bc379a4..3671986ea056 100644 --- a/drivers/firmware/arm_scmi/virtio.c +++ b/drivers/firmware/arm_scmi/virtio.c @@ -389,8 +389,11 @@ static int scmi_vio_probe(struct virtio_device *vdev) struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT]; /* Only one SCMI VirtiO device allowed */ - if (scmi_vdev) - return -EINVAL; + if (scmi_vdev) { + dev_err(dev, + "One SCMI Virtio device was already initialized: only one allowed.\n"); + return -EBUSY; + } have_vq_rx = scmi_vio_have_vq_rx(vdev); vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1; @@ -433,7 +436,8 @@ static int scmi_vio_probe(struct virtio_device *vdev) } vdev->priv = channels; - scmi_vdev = vdev; + /* Ensure initialized scmi_vdev is visible */ + smp_store_mb(scmi_vdev, vdev); return 0; } @@ -449,7 +453,8 @@ static void scmi_vio_remove(struct virtio_device *vdev) */ vdev->config->reset(vdev); vdev->config->del_vqs(vdev); - scmi_vdev = NULL; + /* Ensure scmi_vdev is visible as NULL */ + smp_store_mb(scmi_vdev, NULL); } static int scmi_vio_validate(struct virtio_device *vdev)