From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3E0F63C37 for ; Tue, 8 Aug 2023 16:12:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9789FC433C8; Tue, 8 Aug 2023 16:12:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691511134; bh=3dtzfUCD+LNNd3R69riKgojTMmB3iwvo7xJjgLrGkV8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=q34GiRU8y8r2pRb0qHmcFZnOhscY+xDmlIhH4L0ZUdaIi96k4MWtFeaF6KVLQsIf5 m0QmQWwAZrGpPjOcunyJx/WxYukvd54B282f21cpE2jLkclk0ekzlUvBUBcJZmsLvq qdQO9uVszwltdLW8tltgXFkKVPceYj1CZze8+KlaywbUxg9fYeEbEXuAP+p0swyE8+ 1ejWJW9Y2WKOG8euvAgq4ji6Vu4W6ylOYb694tlUBBBD1240Wtqgmuvjy7Bb7fgaGc lKRcSMIF+6pIZ+GuYZ6P4rKeBks4z/XTR0AsBK/2Qo13ldQcq3kDbvV8EmbG9VGrSj RbTA3xdakPSaQ== Date: Tue, 8 Aug 2023 17:12:09 +0100 From: Will Deacon To: zhurui Cc: Nicolin Chen , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Robin Murphy , Joerg Roedel , Lu Baolu , Jason Gunthorpe , Yicong Yang , Tomas Krcka , Jean-Philippe Brucker Subject: Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command Message-ID: <20230808161208.GA2890@willie-the-truck> 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> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <015b4573-9d74-451b-8028-a1050ade7019@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) On Sun, Aug 06, 2023 at 01:28:04PM +0800, 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. Yes, thanks, you're quite right. I'm not sure what I was thinking! Will