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,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 A37D6C43333 for ; Mon, 15 Mar 2021 14:38:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78FC764E41 for ; Mon, 15 Mar 2021 14:38:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240651AbhCOOiO (ORCPT ); Mon, 15 Mar 2021 10:38:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:34900 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233301AbhCOOBX (ORCPT ); Mon, 15 Mar 2021 10:01:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B274B64F0F; Mon, 15 Mar 2021 14:00:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615816843; bh=QqIb48+Ukc15hLW4U4uQXWuOsnlZR//HBG724wX1G3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V2m5ekUXMCo4nd8uIBZEyS7pK8PSf6J6fj0FB10/BQoJx17Isq//PJgv0D5tCuElD IA3qaQ5n27lw6JgrCqlTFtbV11Wz5fyorflWqi9I+1iRFqlNgG3wxcNr0wOL85OG8n LjiIcvlENXN96ht5XkBpNubghrXs1sGpSoXfv974= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suravee Suthikulpanit , "Tj (Elloe Linux)" , Joerg Roedel , Sasha Levin Subject: [PATCH 5.10 146/290] iommu/amd: Fix performance counter initialization Date: Mon, 15 Mar 2021 14:53:59 +0100 Message-Id: <20210315135546.844302411@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135541.921894249@linuxfoundation.org> References: <20210315135541.921894249@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman From: Suravee Suthikulpanit [ Upstream commit 6778ff5b21bd8e78c8bd547fd66437cf2657fd9b ] Certain AMD platforms enable power gating feature for IOMMU PMC, which prevents the IOMMU driver from updating the counter while trying to validate the PMC functionality in the init_iommu_perf_ctr(). This results in disabling PMC support and the following error message: "AMD-Vi: Unable to read/write to IOMMU perf counter" To workaround this issue, disable power gating temporarily by programming the counter source to non-zero value while validating the counter, and restore the prior state afterward. Signed-off-by: Suravee Suthikulpanit Tested-by: Tj (Elloe Linux) Link: https://lore.kernel.org/r/20210208122712.5048-1-suravee.suthikulpanit@amd.com Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201753 Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin --- drivers/iommu/amd/init.c | 45 ++++++++++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 11 deletions(-) diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index c842545368fd..3c215f0a6052 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -254,6 +255,8 @@ static enum iommu_init_state init_state = IOMMU_START_STATE; static int amd_iommu_enable_interrupts(void); static int __init iommu_go_to_state(enum iommu_init_state state); static void init_device_table_dma(void); +static int iommu_pc_get_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, + u8 fxn, u64 *value, bool is_write); static bool amd_iommu_pre_enabled = true; @@ -1717,13 +1720,11 @@ static int __init init_iommu_all(struct acpi_table_header *table) return 0; } -static int iommu_pc_get_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, - u8 fxn, u64 *value, bool is_write); - -static void init_iommu_perf_ctr(struct amd_iommu *iommu) +static void __init init_iommu_perf_ctr(struct amd_iommu *iommu) { + int retry; struct pci_dev *pdev = iommu->dev; - u64 val = 0xabcd, val2 = 0, save_reg = 0; + u64 val = 0xabcd, val2 = 0, save_reg, save_src; if (!iommu_feature(iommu, FEATURE_PC)) return; @@ -1731,17 +1732,39 @@ static void init_iommu_perf_ctr(struct amd_iommu *iommu) amd_iommu_pc_present = true; /* save the value to restore, if writable */ - if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, false)) + if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, false) || + iommu_pc_get_set_reg(iommu, 0, 0, 8, &save_src, false)) goto pc_false; - /* Check if the performance counters can be written to */ - if ((iommu_pc_get_set_reg(iommu, 0, 0, 0, &val, true)) || - (iommu_pc_get_set_reg(iommu, 0, 0, 0, &val2, false)) || - (val != val2)) + /* + * Disable power gating by programing the performance counter + * source to 20 (i.e. counts the reads and writes from/to IOMMU + * Reserved Register [MMIO Offset 1FF8h] that are ignored.), + * which never get incremented during this init phase. + * (Note: The event is also deprecated.) + */ + val = 20; + if (iommu_pc_get_set_reg(iommu, 0, 0, 8, &val, true)) goto pc_false; + /* Check if the performance counters can be written to */ + val = 0xabcd; + for (retry = 5; retry; retry--) { + if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &val, true) || + iommu_pc_get_set_reg(iommu, 0, 0, 0, &val2, false) || + val2) + break; + + /* Wait about 20 msec for power gating to disable and retry. */ + msleep(20); + } + /* restore */ - if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, true)) + if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, true) || + iommu_pc_get_set_reg(iommu, 0, 0, 8, &save_src, true)) + goto pc_false; + + if (val != val2) goto pc_false; pci_info(pdev, "IOMMU performance counters supported\n"); -- 2.30.1