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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF394C1975A for ; Wed, 25 Mar 2020 16:16:08 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CA05C2073E for ; Wed, 25 Mar 2020 16:16:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jcecU4lF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA05C2073E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.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=w4r0mHkb6zhsGpcTwxfN6uT9hOY14TzXqdeHcnCPeTQ=; b=jcecU4lFqZQn4v 3DsESGsxl/35SWYSVcxe23WMjnBM6TxMODCwckrYGy9rZ1XpB/VGb51xOrvPW/CFueX9A8kCA+0Ir rGSMqLN2MHAGigf5rgU9S7O/P0wI6LyOsnXxkKttbTRukdH5N4AnRZZ/qZaAe5HyoXZTtyxm3FZsZ kB43LYfz+OLSaHQfArqJwP0xTFY7sF9nVt4AHQvJIOsKyHNzCl6gd7c94ca4JYoX9+GfEZpKL7cV+ 4ufJQ9Ob9/mH6hk55L7fMd6sSt9tLVIpNnku9dq0tNLISCHTP3iV5pr/Z3fqHpdlMXqmB6oEm+8Aa ljMVGPqi7cRYURu8smgg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jH8hJ-00025O-PN; Wed, 25 Mar 2020 16:16:05 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jH8hG-00024X-8s for linux-arm-kernel@lists.infradead.org; Wed, 25 Mar 2020 16:16:04 +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 826631FB; Wed, 25 Mar 2020 09:16:00 -0700 (PDT) Received: from [172.16.1.108] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9CDEA3F52E; Wed, 25 Mar 2020 09:15:56 -0700 (PDT) Subject: Re: [RFC PATCH v4 0/6] arm64: tlb: add support for TTL feature To: Zhenyu Ye References: <20200324134534.1570-1-yezhenyu2@huawei.com> From: James Morse Openpgp: preference=signencrypt Message-ID: Date: Wed, 25 Mar 2020 16:15:58 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200324134534.1570-1-yezhenyu2@huawei.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200325_091602_355844_EF79C375 X-CRM114-Status: GOOD ( 14.05 ) 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: mark.rutland@arm.com, peterz@infradead.org, catalin.marinas@arm.com, linux-mm@kvack.org, guohanjun@huawei.com, will@kernel.org, linux-arch@vger.kernel.org, yuzhao@google.com, maz@kernel.org, steven.price@arm.com, arm@kernel.org, Dave.Martin@arm.com, arnd@arndb.de, suzuki.poulose@arm.com, npiggin@gmail.com, zhangshaokun@hisilicon.com, broonie@kernel.org, rostedt@goodmis.org, prime.zeng@hisilicon.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, xiexiangyou@huawei.com, linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Zhenyu, On 3/24/20 1:45 PM, Zhenyu Ye wrote: > In order to reduce the cost of TLB invalidation, the ARMv8.4 TTL > feature allows TLBs to be issued with a level allowing for quicker > invalidation. This series provide support for this feature. > > Patch 1 and Patch 2 was provided by Marc on his NV series[1] patches, > which detect the TTL feature and add __tlbi_level interface. How does this interact with THP? (I don't see anything on that in the series.) With THP, there is no one answer to the size of mapping in a VMA. This is a problem because the arm-arm has in "Translation table level hints" in D5.10.2 of DDI0487E.a: | If an incorrect value for the entry being invalidated by the | instruction is specified in the TTL field, then no entries are | required by the architecture to be invalidated from the TLB. If we get it wrong, not TLB maintenance occurs! Unless THP leaves its fingerprints on the vma, I think you can only do this for VMA types that THP can't mess with. (see transparent_hugepage_enabled()) Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel