From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5407310EA for ; Sun, 6 Aug 2023 05:28:15 +0000 (UTC) Received: from canpemm500006.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RJScd716vz1K97H; Sun, 6 Aug 2023 13:26:57 +0800 (CST) Received: from [10.67.145.224] (10.67.145.224) by canpemm500006.china.huawei.com (7.192.105.130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Sun, 6 Aug 2023 13:28:04 +0800 Subject: Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command To: Nicolin Chen , Will Deacon CC: , , , Robin Murphy , 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> From: zhurui Message-ID: <015b4573-9d74-451b-8028-a1050ade7019@huawei.com> Date: Sun, 6 Aug 2023 13:28:04 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.145.224] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500006.china.huawei.com (7.192.105.130) X-CFilter-Loop: Reflected 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. > > 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 .