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 CF773C5ACC5 for ; Wed, 19 Feb 2020 23:33:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B0E1624656 for ; Wed, 19 Feb 2020 23:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726777AbgBSXc7 (ORCPT ); Wed, 19 Feb 2020 18:32:59 -0500 Received: from mga09.intel.com ([134.134.136.24]:54129 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726680AbgBSXc6 (ORCPT ); Wed, 19 Feb 2020 18:32:58 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Feb 2020 15:32:57 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,462,1574150400"; d="scan'208";a="382956888" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.254.209.152]) ([10.254.209.152]) by orsmga004.jf.intel.com with ESMTP; 19 Feb 2020 15:32:54 -0800 Subject: Re: [PATCH] iommu/vt-d: Fix a bug in intel_iommu_iova_to_phys() for huge page To: Yonghyun Hwang , Moritz Fischer Cc: David Woodhouse , Joerg Roedel , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Havard Skinnemoen , Deepa Dinamani , Moritz Fischer References: <20200218222324.231915-1-yonghyun@google.com> <8efc6ea2-d51e-624c-5cc2-4049bb224122@linux.intel.com> <20200219044235.GA1397@epycbox.lan> From: Lu Baolu Message-ID: <9e3f1bb8-bbfd-174c-b7a7-617dea7c2c9a@linux.intel.com> Date: Thu, 20 Feb 2020 07:32:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 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 Hi, On 2020/2/20 2:51, Yonghyun Hwang wrote: > Hello Lu and Moritz, > > I think it's better to keep "if (level > 1)" because > level_to_offset_bits() returns (unsigned int) -1 * LEVEL_STRIDE if level > becomes 0. @level will never be 0 in this case. Best regards, baolu > > static inline unsigned int level_to_offset_bits(int level) > { >   return (level - 1) * LEVEL_STRIDE; > } > > On Tue, Feb 18, 2020 at 8:42 PM Moritz Fischer > wrote: > > Hi Baolu, Yonghyun > > On Wed, Feb 19, 2020 at 11:15:36AM +0800, Lu Baolu wrote: > > Hi Yonghyun, > > > > Thanks for the patch. > > > > On 2020/2/19 6:23, Yonghyun Hwang wrote: > > > intel_iommu_iova_to_phys() has a bug when it translates an IOVA > for a huge > > > page onto its corresponding physical address. This commit fixes > the bug by > > > accomodating the level of page entry for the IOVA and adds > IOVA's lower > > > address to the physical address. > > > > Signed-off-by: Yonghyun Hwang > > > > --- > > >   drivers/iommu/intel-iommu.c | 11 +++++++++-- > > >   1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > > index 0c8d81f56a30..ed6e69adb578 100644 > > > --- a/drivers/iommu/intel-iommu.c > > > +++ b/drivers/iommu/intel-iommu.c > > > @@ -5555,13 +5555,20 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct iommu_domain *domain, > > >     struct dma_pte *pte; > > >     int level = 0; > > >     u64 phys = 0; > > > +   const unsigned long pfn = iova >> VTD_PAGE_SHIFT; > > > > Why do you need a "const unsigned long" here? > > > > It's because pfn_to_dma_pte() takes pfn for its second parameter as > "unsigned int" type and pfn is not changed in intel_iommu_iova_to_phys(). > > > > > >     if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN) > > >             return 0; > > > -   pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > > -   if (pte) > > > +   pte = pfn_to_dma_pte(dmar_domain, pfn, &level); > > > +   if (pte) { > > >             phys = dma_pte_addr(pte); > > > +           if (level > 1) > > > +                   phys += (pfn & > > > +                           ((1UL << > level_to_offset_bits(level)) - 1)) > > > +                           << VTD_PAGE_SHIFT; > > > +           phys += iova & (VTD_PAGE_SIZE - 1); > > > > How about > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > index 9dc37672bf89..bd17c2510bb2 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -5693,8 +5693,14 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct > > iommu_domain *domain, > >         u64 phys = 0; > > > >         pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > -       if (pte) > > +       if (pte) { > > +               unsigned long offset_mask; > > + > > +               offset_mask = BIT_MASK(level_to_offset_bits(level) + > > +                                      VTD_PAGE_SHIFT) - 1; > >                 phys = dma_pte_addr(pte); > > +               phys += iova & (bitmask - 1); > Did you mean: > > phys += iova & (offset_mask - 1); > > > +       } > > At that point why not define a helper: > > static inline unsigned long offset_mask(int level) > { >         return BIT_MASK(level_to_offset_bits(level) + > VTD_PAGE_SHIFT) - 1; > } > > At which point the above would reduce to: > > if (pte) >         phys = dma_pte_addr(pte) + iova & offset_mask(level) - 1; > > > > Let me introduce the helper function and upstream the patch again. Thank > you Lu and Moritz. > > > I might've fatfingered something here, but you get the idea :) > > Cheers, > Moritz > > > On Tue, Feb 18, 2020 at 8:42 PM Moritz Fischer > wrote: > > Hi Baolu, Yonghyun > > On Wed, Feb 19, 2020 at 11:15:36AM +0800, Lu Baolu wrote: > > Hi Yonghyun, > > > > Thanks for the patch. > > > > On 2020/2/19 6:23, Yonghyun Hwang wrote: > > > intel_iommu_iova_to_phys() has a bug when it translates an IOVA > for a huge > > > page onto its corresponding physical address. This commit fixes > the bug by > > > accomodating the level of page entry for the IOVA and adds > IOVA's lower > > > address to the physical address. > > > > Signed-off-by: Yonghyun Hwang > > > > --- > > >   drivers/iommu/intel-iommu.c | 11 +++++++++-- > > >   1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > > index 0c8d81f56a30..ed6e69adb578 100644 > > > --- a/drivers/iommu/intel-iommu.c > > > +++ b/drivers/iommu/intel-iommu.c > > > @@ -5555,13 +5555,20 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct iommu_domain *domain, > > >     struct dma_pte *pte; > > >     int level = 0; > > >     u64 phys = 0; > > > +   const unsigned long pfn = iova >> VTD_PAGE_SHIFT; > > > > Why do you need a "const unsigned long" here? > > > > >     if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN) > > >             return 0; > > > -   pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > > -   if (pte) > > > +   pte = pfn_to_dma_pte(dmar_domain, pfn, &level); > > > +   if (pte) { > > >             phys = dma_pte_addr(pte); > > > +           if (level > 1) > > > +                   phys += (pfn & > > > +                           ((1UL << > level_to_offset_bits(level)) - 1)) > > > +                           << VTD_PAGE_SHIFT; > > > +           phys += iova & (VTD_PAGE_SIZE - 1); > > > > How about > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > index 9dc37672bf89..bd17c2510bb2 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -5693,8 +5693,14 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct > > iommu_domain *domain, > >         u64 phys = 0; > > > >         pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > -       if (pte) > > +       if (pte) { > > +               unsigned long offset_mask; > > + > > +               offset_mask = BIT_MASK(level_to_offset_bits(level) + > > +                                      VTD_PAGE_SHIFT) - 1; > >                 phys = dma_pte_addr(pte); > > +               phys += iova & (bitmask - 1); > Did you mean: > > phys += iova & (offset_mask - 1); > > > +       } > > At that point why not define a helper: > > static inline unsigned long offset_mask(int level) > { >         return BIT_MASK(level_to_offset_bits(level) + > VTD_PAGE_SHIFT) - 1; > } > > At which point the above would reduce to: > > if (pte) >         phys = dma_pte_addr(pte) + iova & offset_mask(level) - 1; > > I might've fatfingered something here, but you get the idea :) > > Cheers, > Moritz >