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, 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 E3E95C433E0 for ; Sun, 31 May 2020 07:22:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAFED207C4 for ; Sun, 31 May 2020 07:22:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727069AbgEaHWK (ORCPT ); Sun, 31 May 2020 03:22:10 -0400 Received: from winnie.ispras.ru ([83.149.199.91]:29532 "EHLO smtp.ispras.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726751AbgEaHWK (ORCPT ); Sun, 31 May 2020 03:22:10 -0400 Received: from monopod.intra.ispras.ru (monopod.intra.ispras.ru [10.10.3.121]) by smtp.ispras.ru (Postfix) with ESMTP id C439E203BF; Sun, 31 May 2020 10:22:04 +0300 (MSK) Date: Sun, 31 May 2020 10:22:04 +0300 (MSK) From: Alexander Monakov To: linux-kernel@vger.kernel.org cc: Joerg Roedel , Suravee Suthikulpanit , iommu@lists.linux-foundation.org, Shuah Khan Subject: Re: [PATCH] iommu/amd: Fix event counter availability check In-Reply-To: <20200529200738.1923-1-amonakov@ispras.ru> Message-ID: References: <20200529200738.1923-1-amonakov@ispras.ru> User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, 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. Thanks. Alexander 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. > > 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 >