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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 BD247C433E0 for ; Mon, 1 Jun 2020 02:48:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9EABA207D5 for ; Mon, 1 Jun 2020 02:48:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727847AbgFACsF (ORCPT ); Sun, 31 May 2020 22:48:05 -0400 Received: from mx3.molgen.mpg.de ([141.14.17.11]:54871 "EHLO mx1.molgen.mpg.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727808AbgFACsE (ORCPT ); Sun, 31 May 2020 22:48:04 -0400 Received: from [192.168.178.35] (unknown [94.134.88.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: pmenzel) by mx.molgen.mpg.de (Postfix) with ESMTPSA id BF0D82002EE14; Mon, 1 Jun 2020 04:48:01 +0200 (CEST) Subject: Re: [PATCH] iommu/amd: Fix event counter availability check To: Alexander Monakov , linux-kernel@vger.kernel.org Cc: iommu@lists.linux-foundation.org, Shuah Khan , =?UTF-8?B?SsO2cmcgUsO2ZGVs?= , Suravee Suthikulpanit References: <20200529200738.1923-1-amonakov@ispras.ru> From: Paul Menzel Message-ID: <1b2652e9-903e-c02f-8393-2775ae60f0b4@molgen.mpg.de> Date: Mon, 1 Jun 2020 04:48:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Alexander, Thank you very much for the patch. Am 31.05.20 um 09:22 schrieb Alexander Monakov: > Adding Shuah Khan to Cc: I've noticed you've seen this issue on Ryzen 2400GE; > can you have a look at the patch? Would be nice to know if it fixes the > problem for you too. > On Fri, 29 May 2020, Alexander Monakov wrote: > >> The driver performs an extra check if the IOMMU's capabilities advertise >> presence of performance counters: it verifies that counters are writable >> by writing a hard-coded value to a counter and testing that reading that >> counter gives back the same value. >> >> Unfortunately it does so quite early, even before pci_enable_device is >> called for the IOMMU, i.e. when accessing its MMIO space is not >> guaranteed to work. On Ryzen 4500U CPU, this actually breaks the test: >> the driver assumes the counters are not writable, and disables the >> functionality. >> >> Moving init_iommu_perf_ctr just after iommu_flush_all_caches resolves >> the issue. This is the earliest point in amd_iommu_init_pci where the >> call succeeds on my laptop. >> >> Signed-off-by: Alexander Monakov >> Cc: Joerg Roedel >> Cc: Suravee Suthikulpanit >> Cc: iommu@lists.linux-foundation.org >> --- >> >> PS. I'm seeing another hiccup with IOMMU probing on my system: >> pci 0000:00:00.2: can't derive routing for PCI INT A >> pci 0000:00:00.2: PCI INT A: not connected >> >> Hopefully I can figure it out, but I'd appreciate hints. I guess it’s a firmware bug, but I contacted the linux-pci folks [1]. >> drivers/iommu/amd_iommu_init.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c >> index 5b81fd16f5fa..1b7ec6b6a282 100644 >> --- a/drivers/iommu/amd_iommu_init.c >> +++ b/drivers/iommu/amd_iommu_init.c >> @@ -1788,8 +1788,6 @@ static int __init iommu_init_pci(struct amd_iommu *iommu) >> if (iommu->cap & (1UL << IOMMU_CAP_NPCACHE)) >> amd_iommu_np_cache = true; >> >> - init_iommu_perf_ctr(iommu); >> - >> if (is_rd890_iommu(iommu->dev)) { >> int i, j; >> >> @@ -1891,8 +1889,10 @@ static int __init amd_iommu_init_pci(void) >> >> init_device_table_dma(); >> >> - for_each_iommu(iommu) >> + for_each_iommu(iommu) { >> iommu_flush_all_caches(iommu); >> + init_iommu_perf_ctr(iommu); >> + } >> >> if (!ret) >> print_iommu_info(); >> >> base-commit: 75caf310d16cc5e2f851c048cd597f5437013368 Thank you very much for fixing this issue, which is almost two years old for me. Tested-by: Paul Menzel MSI MSI MS-7A37/B350M MORTAR with AMD Ryzen 3 2200G Link: https://lore.kernel.org/linux-iommu/20180727102710.GA6738@8bytes.org/ Kind regards, Paul [1]: https://lore.kernel.org/linux-pci/8579bd14-e369-1141-917b-204d20cff528@molgen.mpg.de/