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 X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 74FDBC433E0 for ; Tue, 2 Mar 2021 13:02:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2750061494 for ; Tue, 2 Mar 2021 13:02:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383953AbhCBM7j (ORCPT ); Tue, 2 Mar 2021 07:59:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:40260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238436AbhCBL7i (ORCPT ); Tue, 2 Mar 2021 06:59:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9985D64F1A; Tue, 2 Mar 2021 11:55:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614686147; bh=vjK9Yoh09+V3t6zi3JGagRb0lPiPc42XU6p6uKAzd8M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=klS+3w7TISHCQGPsY0uKCIsw6AU3RSkfbs9c6yzYRCoYaQ6XMAolL4n5LnYGOSDTl lb2gwBZ1BJ47f8tYLD0z0v+QAXAMN9EAHRdL5hhdAD85JH+lU5CTqDtKtLbNCEXM+Z NPZgjm8uaSgpsjPButMMpAJwGqOKdBioiBFyZ8QOYOZgWzCU8jRD8g07cbIgdVgGmB g38u+Y2Gis9Tq0+FLp8C9qC3u7ygogQpaVe8AES6IqMs50Ufz54wZqToEQPoO2zj8t gYo0TLAP9IBxfpBS+DZkzcrjwHN4BM6ve0aZY8TpKv3J2gvQEMJUZPyNbl4jPz+BHc pM9+tF4+mIneQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Lu Baolu , Kevin Tian , Joerg Roedel , Sasha Levin , iommu@lists.linux-foundation.org Subject: [PATCH AUTOSEL 5.11 09/52] iommu/vt-d: Clear PRQ overflow only when PRQ is empty Date: Tue, 2 Mar 2021 06:54:50 -0500 Message-Id: <20210302115534.61800-9-sashal@kernel.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210302115534.61800-1-sashal@kernel.org> References: <20210302115534.61800-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lu Baolu [ Upstream commit 28a77185f1cd0650b664f54614143aaaa3a7a615 ] It is incorrect to always clear PRO when it's set w/o first checking whether the overflow condition has been cleared. Current code assumes that if an overflow condition occurs it must have been cleared by earlier loop. However since the code runs in a threaded context, the overflow condition could occur even after setting the head to the tail under some extreme condition. To be sane, we should read both head/tail again when seeing a pending PRO and only clear PRO after all pending PRs have been handled. Suggested-by: Kevin Tian Signed-off-by: Lu Baolu Link: https://lore.kernel.org/linux-iommu/MWHPR11MB18862D2EA5BD432BF22D99A48CA09@MWHPR11MB1886.namprd11.prod.outlook.com/ Link: https://lore.kernel.org/r/20210126080730.2232859-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin --- drivers/iommu/intel/svm.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c index 18a9f05df407..b3bcd6dec93e 100644 --- a/drivers/iommu/intel/svm.c +++ b/drivers/iommu/intel/svm.c @@ -1079,8 +1079,17 @@ prq_advance: * Clear the page request overflow bit and wake up all threads that * are waiting for the completion of this handling. */ - if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) - writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG); + if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) { + pr_info_ratelimited("IOMMU: %s: PRQ overflow detected\n", + iommu->name); + head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK; + tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK; + if (head == tail) { + writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG); + pr_info_ratelimited("IOMMU: %s: PRQ overflow cleared", + iommu->name); + } + } if (!completion_done(&iommu->prq_complete)) complete(&iommu->prq_complete); -- 2.30.1