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 34CC6C7EE2A for ; Fri, 18 Aug 2023 16:20:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378558AbjHRQTs (ORCPT ); Fri, 18 Aug 2023 12:19:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378569AbjHRQTj (ORCPT ); Fri, 18 Aug 2023 12:19:39 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0457835B8 for ; Fri, 18 Aug 2023 09:19:38 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3E4F0D75; Fri, 18 Aug 2023 09:20:18 -0700 (PDT) Received: from [10.57.91.158] (unknown [10.57.91.158]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B18CC3F762; Fri, 18 Aug 2023 09:19:35 -0700 (PDT) Message-ID: <197e87cd-91a2-dce8-716c-488b379abbaf@arm.com> Date: Fri, 18 Aug 2023 17:19:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command Content-Language: en-GB From: Robin Murphy To: zhurui , Will Deacon Cc: Nicolin Chen , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Joerg Roedel , Lu Baolu , Jason Gunthorpe , Yicong Yang , Tomas Krcka , Jean-Philippe Brucker References: <1690784482-30028-1-git-send-email-wangwudi@hisilicon.com> <20230801085504.GA26130@willie-the-truck> <27c895b8-1fb0-be88-8bc3-878d754684c8@huawei.com> <20230804165225.GF30679@willie-the-truck> <015b4573-9d74-451b-8028-a1050ade7019@huawei.com> <661a7bb5-99e1-de16-d860-0cd17f7a0470@arm.com> <20230808162409.GB2890@willie-the-truck> <80ead8ee-4dbe-7b3c-44f5-944073a2a39d@arm.com> <412886be-644a-5b46-9bfa-1c9a358f9a5d@huawei.com> <280d0be7-7d41-ed78-bf4b-3db6c0076e22@arm.com> In-Reply-To: <280d0be7-7d41-ed78-bf4b-3db6c0076e22@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023-08-09 14:48, Robin Murphy wrote: [...] > Does the patch below work for you? Any comments on this? Just noticed this commit on a local dev branch and realised I'd totally forgotten about it already. I'm pretty confident it ought to be right, but then it *was* also me who missed the original bug to begin with... ;) Thanks, Robin. > ----->8----- > Subject: [PATCH] iommu/arm-smmu-v3: Avoid constructing invalid range > commands > > Although io-pgtable's non-leaf invalidations are always for full tables, > I missed that SVA also uses non-leaf invalidations, while being at the > mercy of whatever range the MMU notifier throws at it. This means it > definitely wants the previous TTL fix as well, since it also doesn't > know exactly which leaf level(s) may need invalidating, but it can also > give us less-aligned ranges wherein certain corners may lead to building > an invalid command where TTL, Num and Scale are all 0. It should be fine > to handle this by over-invalidating an extra page, since falling back to > a non-range command opens up a whole can of errata-flavoured worms. > > Fixes: 6833b8f2e199 ("iommu/arm-smmu-v3: Set TTL invalidation hint better") > Reported-by: Rui Zhu > Signed-off-by: Robin Murphy > --- >  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 ++++++++++----- >  1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 9b0dc3505601..6ccbae9b93a1 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -1895,18 +1895,23 @@ static void __arm_smmu_tlb_inv_range(struct > arm_smmu_cmdq_ent *cmd, >          /* Get the leaf page size */ >          tg = __ffs(smmu_domain->domain.pgsize_bitmap); > > +        num_pages = size >> tg; > + >          /* Convert page size of 12,14,16 (log2) to 1,2,3 */ >          cmd->tlbi.tg = (tg - 10) / 2; > >          /* > -         * Determine what level the granule is at. For non-leaf, > io-pgtable > -         * assumes .tlb_flush_walk can invalidate multiple levels at once, > -         * so ignore the nominal last-level granule and leave TTL=0. > +         * Determine what level the granule is at. For non-leaf, both > +         * io-pgtable and SVA pass a nominal last-level granule because > +         * they don't know what level(s) actually apply, so ignore that > +         * and leave TTL=0. However for various errata reasons we still > +         * want to use a range command, so avoid the SVA corner case > +         * where both scale and num could be 0 as well. >           */ >          if (cmd->tlbi.leaf) >              cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3)); > - > -        num_pages = size >> tg; > +        else if ((num_pages & CMDQ_TLBI_RANGE_NUM_MAX) == 1) > +            num_pages++; >      } > >      cmds.num = 0; >