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 D7FBFC433DB for ; Wed, 3 Mar 2021 00:47:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF77664F9A for ; Wed, 3 Mar 2021 00:47:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239251AbhCCA3H (ORCPT ); Tue, 2 Mar 2021 19:29:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:51136 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345670AbhCBMgL (ORCPT ); Tue, 2 Mar 2021 07:36:11 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id BDA8964F51; Tue, 2 Mar 2021 11:56:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614686216; bh=gHCNSIIJBpDDyHuxZ94L+MAHMGyBEwM33M/mylZiORs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WFdgLGGV+QL8pvSAPKHii4jUCUSimpqoIrACdhNQHZAStnsCuxnHJarSZNOlAeIk4 +YAcrX3shcA64ogxve0ShiRvgNf2lpdihNhato9zFVUmW7iL30tJuuZYaWJH98uVtV OjtmB9sbN5mKN2P9/HQy43I7f2ecmm/DjuAGEMn6JwhZgYUbHRqqaXRws/3LByj5/b nvgl7jgcXTBlZ9YO1heww9qsuQ5E548HVEGRT3qoNbIm4vTEtrxYRUHiVgw7u2X4fG XIkJa0sg6Mv6hsr5K7nj1l3dkotQg6a3Y9495x6w4kO55tk+2nQ4GcLL86kiiAXrSe JtWVC7yyMo67Q== 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 5.10 07/47] iommu/vt-d: Clear PRQ overflow only when PRQ is empty Date: Tue, 2 Mar 2021 06:56:06 -0500 Message-Id: <20210302115646.62291-7-sashal@kernel.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210302115646.62291-1-sashal@kernel.org> References: <20210302115646.62291-1-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: stable@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 43f392d27d31..b200a3acc6ed 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