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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 08D61C43381 for ; Fri, 1 Mar 2019 11:35:27 +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 C2FDD20851 for ; Fri, 1 Mar 2019 11:35:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PSskpi2Y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2FDD20851 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:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VJXmNLUtHLHRUqdZ98qKxmqMum1LV+3Re0tFcwtFEl8=; b=PSskpi2YJWyJ7a 6/JITvhe3rdkbz+R48kyUiccw+VE5dC3S5qyYqZx+beoRuN9UbD2s2iUfkUwxgtiVRd1p6Vn35nnV fjF3GjACO+TWnby4EW5oRWU1U+hvcD4almRJQBdA/VzYYlJEhc3InC3f2lE8qW3ux7/hKzKvyy3xl jiVuHYBRvKVbPTC3pEEmxXZ7fSFm0frOMj02lDL1taBnINgNi6K5iljc9hv2tndqcozvz0WhbzTlJ brpsln1mBGZEtvRuQAyIJMRvcuE6bE/8+hn3GAHBD4Sml5saIyFMnUZGEE/O7ykdVmRWI9g9iB2ib pAZlZ2GujzWv8uZXXzGg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gzgRp-0004CP-Uc; Fri, 01 Mar 2019 11:35:25 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gzgRm-0003ys-9z for linux-arm-kernel@lists.infradead.org; Fri, 01 Mar 2019 11:35:23 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 838F8EBD; Fri, 1 Mar 2019 03:35:19 -0800 (PST) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 08A9E3F5C1; Fri, 1 Mar 2019 03:35:17 -0800 (PST) Date: Fri, 1 Mar 2019 11:35:12 +0000 From: Will Deacon To: John Garry Subject: Re: [PATCH] arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on Message-ID: <20190301113512.GA22488@fuggles.cambridge.arm.com> References: <20190115184917.248995-1-james.morse@arm.com> <21310b0b-8a75-1adf-a844-b2f3f520fa2d@huawei.com> <835dc899-578c-d914-4ed3-fa8b3b391ae6@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <835dc899-578c-d914-4ed3-fa8b3b391ae6@huawei.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190301_033522_353226_42510AEB X-CRM114-Status: GOOD ( 16.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ard Biesheuvel , Catalin Marinas , Linuxarm , James Morse , huangdaode , "Guohanjun \(Hanjun Guo\)" , linux-arm-kernel@lists.infradead.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 On Fri, Mar 01, 2019 at 11:18:21AM +0000, John Garry wrote: > On 16/01/2019 09:38, John Garry wrote: > > On 15/01/2019 18:49, James Morse wrote: > > > Since commit b89d82ef01b3 ("arm64: kpti: Avoid rewriting early page > > > > About b89d82ef01b3, I got an *unconfirmed* (emphasis on this, I don't > > want to cry wolf) report yesterday that the symptom I saw (boot delay) > > has been seen on 5.0-rc2 on our D06 board. I could not see it. > > > > Please note that this would be same board which we saw this on: > > https://lkml.org/lkml/2018/6/20/589 > > > > I only witnessed the issue on the predecessor A72-based D05 board. > > > > The reporter is very busy, but we'll keep tabs on it. > > > > FYI, this just came in this morning: This isn't completely surprising, because the kernel doesn't know about the CPU in D06: > [ 0.000000] Booting Linux on physical CPU 0x0000010000 [0x480fd010] [...] > [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI) If the CPU is not affected by meltdown, you can add the MIDR above to the kpti_safe_list[] table. If it *is* affected by meltdown, then I'm afraid that you're stuck with the delay at boot for !KASLR kernels (which is an awful lot better than getting pwned by userspace :) I think D06 is 8.2, so I would've hoped that you'd implemented AA64PFR0_EL1.CSV3, which would make this MIDR-based whitelisting unnecessary. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel