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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ACCD8C001DE for ; Mon, 7 Aug 2023 19:21:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=o1aN57WUpHeyIdaOqRCSzozHDZzRWDbeH3lr8hTX2nw=; b=a7uA5WztmeH0Lw V6c9btHDumjkzT+uKXEOJw0rCS/5oGSEX3NdoTb/g164lgsP3owPVwuRRgJtj6epWoIAjXOq1IFZy J53MDiBKw/MTSG8Ksg+Ojbkz4jxtUW/aM3/2a6ixwYfaZ7cexXAhky4a9znQeWt/ef4Vm6KwzQmIN 5CJLXvunt2BohBdPrTkbIEDHQhGr0scEf9au5qJuoOt9GSYDqb9iIvgIv96HIDcGzu0B+lZVGPZML jJIAzHLZnWVuqOY8XuIqfAYD9mv3sT8ZLm4m2ORsWPi/iN9E1az06f+U8A+7CvaY22VKMPrQv15At 6xw887t3h528cb/rWhdA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qT5mx-000UWw-0O; Mon, 07 Aug 2023 19:21:11 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qT5mu-000UVw-2C for linux-arm-kernel@lists.infradead.org; Mon, 07 Aug 2023 19:21:10 +0000 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 49DAE1FB; Mon, 7 Aug 2023 12:21:47 -0700 (PDT) Received: from [192.168.1.102] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 50E903F64C; Mon, 7 Aug 2023 12:21:02 -0700 (PDT) Message-ID: <661a7bb5-99e1-de16-d860-0cd17f7a0470@arm.com> Date: Mon, 7 Aug 2023 20:20:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command Content-Language: en-GB To: zhurui , Nicolin Chen , Will Deacon Cc: 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> From: Robin Murphy In-Reply-To: <015b4573-9d74-451b-8028-a1050ade7019@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230807_122108_811004_C0284FF1 X-CRM114-Status: GOOD ( 23.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2023-08-06 06:28, zhurui wrote: > On 2023/8/5 2:30, Nicolin Chen wrote: >> On Fri, Aug 04, 2023 at 05:52:25PM +0100, Will Deacon wrote: >>> On Fri, Aug 04, 2023 at 05:31:20PM +0800, zhurui wrote: >>>> When tg != 0 but ttl, scale, num all 0 in a range tlbi command, it >>>> is reserved and will cause the CERROR_ILL error. This case means >>>> that the size to be invalidated is only one page size, and the >>>> range invalidation is meaningless here. So we set tg to 0 in this >>>> case to do an non-range invalidation instead. >> >>>> @@ -1930,6 +1927,12 @@ static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd, >>>> num = (num_pages >> scale) & CMDQ_TLBI_RANGE_NUM_MAX; >>>> cmd->tlbi.num = num - 1; >>>> >>>> + /* Prevent error caused by one page tlbi with leaf 0 */ >>>> + if (scale == 0 && num == 1 && cmd->tlbi.leaf == 0) >>>> + cmd->tlbi.tg = 0; >>> >>> This should only be true for the last iteration, right (i.e. when num_pages >>> == 1)? In which case, I'd prefer to leave the old code as-is and just add: >>> >>> /* Single-page leaf invalidation requires a TG field of 0 */ >>> if (num_pages == 1 && !cmd->tlbi.leaf) >>> cmd->tlbi.tg = 0;To Will and Nicolin, > > Not only the last iteration, it's the result of __ffs function. For example, if > numpages is 33, then the value of __ffs(num_pages) is 0, so the value of scale > is also 0. The value of num depends on CMDQ_TLBI_RANGE_NUM_MAX. That is, the > maximum value of num is 31. Therefore, the final value of num is 1. > So, if consider CMDQ_TLBI_RANGE_NUM_MAX, there will be some case not the last > one page but the beginning pages. That's why I use scale and num as conditions, > not num_pages. Then I should reassign tg based on the result. Yeah, I'd rather not downgrade to a non-range invalidate since that complicates the reasoning for the errata affecting those. If the size of the invalidation is equal to TG then it can only represent a single last-level page, i.e. TTL=3, thus if it does warrant handling here then indeed rearranging to base the condition on num_pages as well ought to suffice. However, this is all still begging the question of where and why we're doing a *non-leaf* invalidation that isn't aligned to the size of a table, because that in itself doesn't make a whole heap of sense - my hunch is that that wants figuring out and could probably be fixed at the source. Thanks, Robin. > >> >> Is "!cmd->tlbi.leaf" to be "leaf" or "non-leaf"? >> >> IIUIC, this "num_pages == 1" implies "NUM == 0, SCALE == 0" while >> the "!cmd->tlbi.leaf" implies "TTL = 0b00", which in combination >> would result in a CERROR_ILL mentioned by the spec? >> >> I feel this could be more clear by just checking the three fields >> following the spec...> >> Thanks >> Nicolin >> . >> > Yes, based on spec 4.4.1.1 for ARM IHI 0070, after the TLL and TG table, there is a > description for TG != 0b00, and you can check it in the last point. > > Thanks. > ZhuRui > . _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel