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 CC609C433EF for ; Thu, 23 Jun 2022 02:29:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377823AbiFWC3p (ORCPT ); Wed, 22 Jun 2022 22:29:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235053AbiFWC3n (ORCPT ); Wed, 22 Jun 2022 22:29:43 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1318C403CD for ; Wed, 22 Jun 2022 19:29:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655951383; x=1687487383; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=O8dTk/EyqAi+/URxBU6KCoV1F2X9CZR61Iaxw/z5tl0=; b=gI6vgjukuE7TVmBEdiwt18N/FEXalHFC7u74AYFTCI5ugXi7egoQVoub WqJOsw158XZjIPTlp7oh36dBbKLDdINGdhKa0YplV8E4/qVw+KIHMfuDA P3/JF3sNXpKrL0l4bgolyHVTfL/k6NEo/a0F0DIK1HsSm77iZLbYC+C24 7aY/JVlC+ZrLKG88RNR8m07UAQ6HsWnHUB/k8OTYY4/Rk7APZDAKKEGUc U+QG8ANgF4+rXqrhHLJR9z3RcrbKtXg+yxx27G+nUEoNXq1XE7YU4UXSH H55OqB03cxZrSNRlcmKM5G5TAQgu42jQzcriBfY8e0gAHptH8gjLQJXD4 g==; X-IronPort-AV: E=McAfee;i="6400,9594,10386"; a="279371133" X-IronPort-AV: E=Sophos;i="5.92,215,1650956400"; d="scan'208";a="279371133" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 19:29:42 -0700 X-IronPort-AV: E=Sophos;i="5.92,215,1650956400"; d="scan'208";a="644501698" Received: from yutaoxu-mobl.ccr.corp.intel.com (HELO [10.249.172.190]) ([10.249.172.190]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 19:29:38 -0700 Message-ID: Date: Thu, 23 Jun 2022 10:29:35 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Cc: baolu.lu@linux.intel.com, Steve Wahl , Joerg Roedel , Kyung Min Park , David Woodhouse , Will Deacon , iommu , Kevin Tian , Mike Travis , Dimitri Sivanich , Russ Anderson , Linux List Kernel Mailing Subject: Re: [PATCH v3] iommu/vt-d: Make DMAR_UNITS_SUPPORTED a config setting Content-Language: en-US To: Jerry Snitselaar References: <9d6177ac-802f-eb11-4307-b0e49d8126b5@linux.intel.com> <20220615183650.32075-1-steve.wahl@hpe.com> <96984350-3a04-812a-60f1-a09138014fac@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/6/22 23:05, Jerry Snitselaar wrote: > On Wed, Jun 22, 2022 at 7:52 AM Baolu Lu wrote: >> On 2022/6/16 02:36, Steve Wahl wrote: >>> To support up to 64 sockets with 10 DMAR units each (640), make the >>> value of DMAR_UNITS_SUPPORTED adjustable by a config variable, >>> CONFIG_DMAR_UNITS_SUPPORTED, and make it's default 1024 when MAXSMP is >>> set. >>> >>> If the available hardware exceeds DMAR_UNITS_SUPPORTED (previously set >>> to MAX_IO_APICS, or 128), it causes these messages: "DMAR: Failed to >>> allocate seq_id", "DMAR: Parse DMAR table failure.", and "x2apic: IRQ >>> remapping doesn't support X2APIC mode x2apic disabled"; and the system >>> fails to boot properly. >>> >>> Signed-off-by: Steve Wahl >>> Reviewed-by: Kevin Tian >>> --- >>> >>> Note that we could not find a reason for connecting >>> DMAR_UNITS_SUPPORTED to MAX_IO_APICS as was done previously. Perhaps >>> it seemed like the two would continue to match on earlier processors. >>> There doesn't appear to be kernel code that assumes that the value of >>> one is related to the other. >>> >>> v2: Make this value a config option, rather than a fixed constant. The default >>> values should match previous configuration except in the MAXSMP case. Keeping the >>> value at a power of two was requested by Kevin Tian. >>> >>> v3: Make the config option dependent upon DMAR_TABLE, as it is not used without this. >>> >>> drivers/iommu/intel/Kconfig | 7 +++++++ >>> include/linux/dmar.h | 6 +----- >>> 2 files changed, 8 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig >>> index 39a06d245f12..07aaebcb581d 100644 >>> --- a/drivers/iommu/intel/Kconfig >>> +++ b/drivers/iommu/intel/Kconfig >>> @@ -9,6 +9,13 @@ config DMAR_PERF >>> config DMAR_DEBUG >>> bool >>> >>> +config DMAR_UNITS_SUPPORTED >>> + int "Number of DMA Remapping Units supported" >>> + depends on DMAR_TABLE >>> + default 1024 if MAXSMP >>> + default 128 if X86_64 >>> + default 64 >> With this patch applied, the IOMMU configuration looks like: >> >> [*] AMD IOMMU support >> AMD IOMMU Version 2 driver >> [*] Enable AMD IOMMU internals in DebugFS >> (1024) Number of DMA Remapping Units supported <<<< NEW >> [*] Support for Intel IOMMU using DMA Remapping Devices >> [*] Export Intel IOMMU internals in Debugfs >> [*] Support for Shared Virtual Memory with Intel IOMMU >> [*] Enable Intel DMA Remapping Devices by default >> [*] Enable Intel IOMMU scalable mode by default >> [*] Support for Interrupt Remapping >> [*] OMAP IOMMU Support >> [*] Export OMAP IOMMU internals in DebugFS >> [*] Rockchip IOMMU Support >> >> The NEW item looks confusing. It looks to be a generic configurable >> value though it's actually Intel DMAR specific. Any thoughts? >> >> Best regards, >> baolu >> > Would moving it under INTEL_IOMMU at least have it show up below > "Support for Intel IOMMU using DMA Remapping Devices"? I'm not sure it > can be better than that, because IRQ_REMAP selects DMAR_TABLE, so we > can't stick it in the if INTEL_IOMMU section. It's more reasonable to move it under INTEL_IOMMU, but the trouble is that this also stands even if INTEL_IOMMU is not configured. The real problem here is that the iommu sequence ID overflows if DMAR_UNITS_SUPPORTED is not big enough. This is purely a software implementation issue, I am not sure whether user opt-in when building a kernel package could help a lot here. If we can't find a better way, can we just step back? Best regards, baolu