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 EB8AAC678D4 for ; Thu, 2 Mar 2023 13:02:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229811AbjCBNC3 (ORCPT ); Thu, 2 Mar 2023 08:02:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229504AbjCBNC0 (ORCPT ); Thu, 2 Mar 2023 08:02:26 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEF9B3250E; Thu, 2 Mar 2023 05:02:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1677762144; x=1709298144; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=WkXF8/EcCNkfU640/eEExv8Plxnmv/7/V2TBsmDVado=; b=Uh0a4K7mEeXMvg/PeCOo5Tyu4B8hIL+yRYenNwai32v2ci1grdRGxGKq kn4XD3xQrri19advEuqe/INRaX1GXfoHTst1TkOhXzINCMhG63121Nf9v 5JOBCFxemJrAVdToOc04gqsWyuF8oc/XO7gJpvimiEStX2bsAeA1PBxgm Z+p0J1H9ps0GHV8KmDR+JVhnJVvWAU1Tw9YfyUIKf28wLVN8YJcQIarIf DMUFuK99hHQy8Halo5fVWNLOnx3XX2gTr9VC16I1AswWg2I6SaIuk63fw HbN4G2yCQG2D8JZG2mkVRIpRXAAviUKwTWxu/OibqBfOCykK+OaFzZwwj A==; X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="318510061" X-IronPort-AV: E=Sophos;i="5.98,227,1673942400"; d="scan'208";a="318510061" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Mar 2023 05:01:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="624932798" X-IronPort-AV: E=Sophos;i="5.98,227,1673942400"; d="scan'208";a="624932798" Received: from blu2-mobl.ccr.corp.intel.com (HELO [10.254.214.218]) ([10.254.214.218]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Mar 2023 05:01:44 -0800 Message-ID: <3b7fb4d3-1fe9-a3be-46ad-c271be9f96c7@linux.intel.com> Date: Thu, 2 Mar 2023 21:01:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Cc: baolu.lu@linux.intel.com, Robin Murphy , Will Deacon , David Woodhouse , Raj Ashok , "Tian, Kevin" , Yi Liu , "Yu, Fenghua" , Dave Jiang , Kirill Shutemov Subject: Re: [PATCH v4 3/6] iommu/sva: Stop using ioasid_set for SVA Content-Language: en-US To: Jacob Pan , LKML , iommu@lists.linux.dev, Jason Gunthorpe , Joerg Roedel , Jean-Philippe Brucker , Dave Hansen , Thomas Gleixner , X86 Kernel , bp@alien8.de, "H. Peter Anvin" , Peter Zijlstra , corbet@lwn.net, vkoul@kernel.org, dmaengine@vger.kernel.org, linux-doc@vger.kernel.org References: <20230301235646.2692846-1-jacob.jun.pan@linux.intel.com> <20230301235646.2692846-4-jacob.jun.pan@linux.intel.com> From: Baolu Lu In-Reply-To: <20230301235646.2692846-4-jacob.jun.pan@linux.intel.com> 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 2023/3/2 7:56, Jacob Pan wrote: > From: Jason Gunthorpe > > Instead SVA drivers can use a simple global IDA to allocate PASIDs for > each mm_struct. > > Future work would be to allow drivers using the SVA APIs to reserve global > PASIDs from this IDA for their internal use, eg with the DMA API PASID > support. > > Signed-off-by: Jason Gunthorpe > Signed-off-by: Jacob Pan > --- > v4: > - Keep GFP_ATOMIC flag for PASID allocation, will changed to > GFP_KERNEL in a separate patch. > --- > drivers/iommu/iommu-sva.c | 62 ++++++++++----------------------------- > drivers/iommu/iommu-sva.h | 3 -- > 2 files changed, 15 insertions(+), 50 deletions(-) > > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c > index 376b2a9e2543..297852ae5e7c 100644 > --- a/drivers/iommu/iommu-sva.c > +++ b/drivers/iommu/iommu-sva.c > @@ -9,26 +9,13 @@ > #include "iommu-sva.h" > > static DEFINE_MUTEX(iommu_sva_lock); > -static DECLARE_IOASID_SET(iommu_sva_pasid); > +static DEFINE_IDA(iommu_global_pasid_ida); > > -/** > - * iommu_sva_alloc_pasid - Allocate a PASID for the mm > - * @mm: the mm > - * @min: minimum PASID value (inclusive) > - * @max: maximum PASID value (inclusive) > - * > - * Try to allocate a PASID for this mm, or take a reference to the existing one > - * provided it fits within the [@min, @max] range. On success the PASID is > - * available in mm->pasid and will be available for the lifetime of the mm. > - * > - * Returns 0 on success and < 0 on error. > - */ > -int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max) > +static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max) > { > - int ret = 0; > - ioasid_t pasid; > + int ret; > > - if (min == INVALID_IOASID || max == INVALID_IOASID || > + if (min == IOMMU_PASID_INVALID || max == IOMMU_PASID_INVALID || > min == 0 || max < min) It's irrelevant to this patch. Just out of curiosity, why do we need to exclude PASID 0 here? I just had a quick look at PCI spec section 6.20. The spec does not state that PASID 0 is invalid. > return -EINVAL; > > @@ -37,39 +24,20 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max) > if (pasid_valid(mm->pasid)) { > if (mm->pasid < min || mm->pasid >= max) > ret = -EOVERFLOW; > + else > + ret = 0; Nit: If you didn't change "int ret = 0" to "int ret", we don't need above two lines. Did I miss anything? > goto out; > } > > - pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm); > - if (!pasid_valid(pasid)) > - ret = -ENOMEM; > - else > - mm->pasid = ret; > + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_ATOMIC); > + if (ret < min) Nit: ret < 0? ida_alloc_range() returns negative error number on failure. > + goto out; > + mm->pasid = ret; > + ret = 0; > out: > mutex_unlock(&iommu_sva_lock); > return ret; > } > -EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid); > - > -/* ioasid_find getter() requires a void * argument */ > -static bool __mmget_not_zero(void *mm) > -{ > - return mmget_not_zero(mm); > -} > - > -/** > - * iommu_sva_find() - Find mm associated to the given PASID > - * @pasid: Process Address Space ID assigned to the mm > - * > - * On success a reference to the mm is taken, and must be released with mmput(). > - * > - * Returns the mm corresponding to this PASID, or an error if not found. > - */ > -struct mm_struct *iommu_sva_find(ioasid_t pasid) > -{ > - return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero); > -} > -EXPORT_SYMBOL_GPL(iommu_sva_find); Removing iommu_sva_find() has nothing to do with the intention of this patch. Perhaps make it in a separated patch? > > /** > * iommu_sva_bind_device() - Bind a process address space to a device > @@ -241,8 +209,8 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) > > void mm_pasid_drop(struct mm_struct *mm) > { > - if (pasid_valid(mm->pasid)) { > - ioasid_free(mm->pasid); > - mm->pasid = INVALID_IOASID; > - } > + if (likely(!pasid_valid(mm->pasid))) Why is this a likely? > + return; > + > + ida_free(&iommu_global_pasid_ida, mm->pasid); > } > diff --git a/drivers/iommu/iommu-sva.h b/drivers/iommu/iommu-sva.h > index 7215a761b962..c22d0174ad61 100644 > --- a/drivers/iommu/iommu-sva.h > +++ b/drivers/iommu/iommu-sva.h > @@ -8,9 +8,6 @@ > #include > #include > > -int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max); > -struct mm_struct *iommu_sva_find(ioasid_t pasid); > - > /* I/O Page fault */ > struct device; > struct iommu_fault; Best regards, baolu