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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=drpwoclTvGcXXvo6yVwqGe/ODA/26gowZYSsbEI5B7s=; b=JJ2a0hjuQhZwVyCUu3tvbY1hh WwL9mv0O6u4lsiybW0cleAUhuqJx2tNXNuvutf0KruCQQagXIGj6bAlBXQoHj0mBlA0KQNIX3Huu3 AdpljgxZp01nUawADZax1Pj2k1h5QpzidiClJ4RafNb7g6gNOMCt1Q8fZ31CV5scLCOvgZEvebz0x I1Mbe7V3wsAcn5dFX/pMPVQukTr5GOlkfixrXJvl6qSyjVD4V/fBH1xZSenFFJXJSFn0SonflY+ij 5ZccE5hR+E8Naw2XYMDRG7apl+xBnXU77iDZBGvahC8WWcg6TCWNGpiZrgG9xzzKhHFCRLuu+bHAK K2KLaaMuA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5N1r-0002OJ-AZ; Fri, 29 Jan 2021 06:13:11 +0000 Received: from szxga06-in.huawei.com ([45.249.212.32]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5N1n-0002Nb-8U for linux-arm-kernel@lists.infradead.org; Fri, 29 Jan 2021 06:13:09 +0000 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4DRn6g44f9zjDnm; Fri, 29 Jan 2021 14:11:55 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.498.0; Fri, 29 Jan 2021 14:12:47 +0800 Subject: Re: [PATCH 1/1] iommu/arm-smmu-v3: add support for BBML To: Robin Murphy , Will Deacon References: <20201126034230.777-1-thunder.leizhen@huawei.com> <20210122125132.GB24102@willie-the-truck> <1bfd1ca0-953e-e943-f87e-144d5537bd0c@arm.com> <20210126101230.GA29204@willie-the-truck> <8a9685ec-67aa-824f-5429-f408bf79c5ab@huawei.com> <32f4752f-6954-183a-a0c1-b5d719c85b67@huawei.com> <319e3532-4555-7431-9d6f-3c3b7c11a5d9@arm.com> <301590f1-817b-d8eb-1585-31208cba18af@arm.com> From: Keqian Zhu Message-ID: <29fd5c20-faeb-1fd3-6535-4fca60463d01@huawei.com> Date: Fri, 29 Jan 2021 14:12:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <301590f1-817b-d8eb-1585-31208cba18af@arm.com> X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210129_011307_763860_DF566C86 X-CRM114-Status: GOOD ( 12.56 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker , iommu , linux-kernel , linux-arm-kernel , Yang Yingliang Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021/1/29 0:17, Robin Murphy wrote: > On 2021-01-28 15:18, Keqian Zhu wrote: >> >> >> On 2021/1/27 17:39, Robin Murphy wrote: >>> On 2021-01-27 07:36, Keqian Zhu wrote: >>>> >>>> >>>> On 2021/1/27 10:01, Leizhen (ThunderTown) wrote: >>>>> >>>>> >>>>> On 2021/1/26 18:12, Will Deacon wrote: >>>>>> On Mon, Jan 25, 2021 at 08:23:40PM +0000, Robin Murphy wrote: >>>>>>> Now we probably will need some degreee of BBML feature awareness for the >>>>>>> sake of SVA if and when we start using it for CPU pagetables, but I still >>>>>>> cannot see any need to consider it in io-pgtable. >>>>>> >>>>>> Agreed; I don't think this is something that io-pgtable should have to care >>>>>> about. >>>> Hi, >>>> >>>> I have a question here :-). >>>> If the old table is not live, then the break procedure seems unnecessary. Do I miss something? >>> >>> The MMU is allowed to prefetch translations at any time, so not following the proper update procedure could still potentially lead to a TLB conflict, even if there's no device traffic to worry about disrupting. >>> >>> Robin. >> >> Thanks. Does the MMU you mention here includes MMU and SMMU? I know that at SMMU side, ATS can prefetch translation. > > Yes, both - VMSAv8 allows speculative translation table walks, so SMMUv3 inherits from there (per 3.21.1 "Translation tables and TLB invalidation completion behavior"). OK, I Get it. Thanks. Keqian. > > Robin. > >> >> Keqian >>> >>>> Thanks, >>>> Keqian >>>> >>>>> >>>>> Yes, the SVA works in stall mode, and the failed device access requests are not >>>>> discarded. >>>>> >>>>> Let me look for examples. The BBML usage scenario was told by a former colleague. >>>>> >>>>>> >>>>>> Will >>>>>> >>>>>> . >>>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> linux-arm-kernel mailing list >>>>> linux-arm-kernel@lists.infradead.org >>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >>>>> . >>>>> >>>> _______________________________________________ >>>> iommu mailing list >>>> iommu@lists.linux-foundation.org >>>> https://lists.linuxfoundation.org/mailman/listinfo/iommu >>>> >>> . >>> > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel