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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42C14C433F5 for ; Mon, 31 Jan 2022 16:18:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380231AbiAaQSB (ORCPT ); Mon, 31 Jan 2022 11:18:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380310AbiAaQRx (ORCPT ); Mon, 31 Jan 2022 11:17:53 -0500 Received: from theia.8bytes.org (8bytes.org [IPv6:2a01:238:4383:600:38bc:a715:4b6d:a889]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A7EAC061714 for ; Mon, 31 Jan 2022 08:17:53 -0800 (PST) Received: from cap.home.8bytes.org (p549ad610.dip0.t-ipconnect.de [84.154.214.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id 8722650C; Mon, 31 Jan 2022 17:17:51 +0100 (CET) From: Joerg Roedel To: iommu@lists.linux-foundation.org Cc: Joerg Roedel , Suravee Suthikulpanit , Will Deacon , linux-kernel@vger.kernel.org, Maxim Levitsky , Joerg Roedel Subject: [PATCH] iommu/amd: Fix loop timeout issue in iommu_ga_log_enable() Date: Mon, 31 Jan 2022 17:17:49 +0100 Message-Id: <20220131161749.4021-1-joro@8bytes.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel The polling loop for the register change in iommu_ga_log_enable() needs to have a udelay() in it. Otherwise the CPU might be faster than the IOMMU hardware and wrongly trigger the WARN_ON() further down the code stream. Fixes: 8bda0cfbdc1a ("iommu/amd: Detect and initialize guest vAPIC log") Signed-off-by: Joerg Roedel --- drivers/iommu/amd/init.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index dc338acf3338..d2e09d53851f 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -834,6 +834,7 @@ static int iommu_ga_log_enable(struct amd_iommu *iommu) status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET); if (status & (MMIO_STATUS_GALOG_RUN_MASK)) break; + udelay(1); } if (WARN_ON(i >= LOOP_TIMEOUT)) -- 2.34.1