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=-2.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 48E92C43612 for ; Mon, 14 Jan 2019 17:25:15 +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 1B1D02070B for ; Mon, 14 Jan 2019 17:25:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="uCrkMztU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B1D02070B 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=U2ItfkyGoraehenJKe/U7pNSFSu/TPE3pe5UY9VndTk=; b=uCrkMztUFmabKk 9Osu7XT3nRluftm68jrdxrBZXBukFzGLVsIjRy6cPWcUTqJrWB8NIbYMfRX7o/VguvJA77Y3dtyuQ M7S8NVu5IWedg4fd2/17VLzRCKa8e9T0RvQQZ80DeIL/PQOt4t+Xp61vTqb8R/Xi4VDIvEnHD0fQp LVoygxVkEMBu6W0hnsPfK4H6n6ArZ3FaVJRQ49pDgV8UqEy522VUADTQmull2KeqIqx8pvZv0HqGa AYH1EsavadzC0xfU2ANLJk5tycwQC+umec3ePaUwl3HwPgN4OHOOHzZsSplyF3l8kQ/Zz5VeOLwmT /2QJY5Xg1v3EIB2q+yGg==; 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 1gj5z5-0008MQ-Cc; Mon, 14 Jan 2019 17:25:11 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gj5z1-0007Y1-Al for linux-arm-kernel@lists.infradead.org; Mon, 14 Jan 2019 17:25:09 +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 1692BA78; Mon, 14 Jan 2019 09:25:05 -0800 (PST) Received: from [10.1.196.105] (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D24033F5BD; Mon, 14 Jan 2019 09:25:02 -0800 (PST) Subject: Re: [PATCH v8 01/26] arm64: Fix HCR.TGE status for NMI contexts To: Julien Thierry , Catalin Marinas References: <1546956464-48825-1-git-send-email-julien.thierry@arm.com> <1546956464-48825-2-git-send-email-julien.thierry@arm.com> <20190114155634.GB84430@arrakis.emea.arm.com> <229aade3-5bb3-aad4-bd9a-d6220db836c0@arm.com> From: James Morse Message-ID: <41c6dc69-3bdc-2ea1-4862-5f4df9b843dd@arm.com> Date: Mon, 14 Jan 2019 17:25:00 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <229aade3-5bb3-aad4-bd9a-d6220db836c0@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190114_092507_398860_19BCBFAD X-CRM114-Status: GOOD ( 14.26 ) 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: mark.rutland@arm.com, linux-arch@vger.kernel.org, daniel.thompson@linaro.org, Arnd Bergmann , marc.zyngier@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, christoffer.dall@arm.com, joel@joelfernandes.org, 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 Hi guys, On 14/01/2019 16:12, Julien Thierry wrote: > On 14/01/2019 15:56, Catalin Marinas wrote: >> On Tue, Jan 08, 2019 at 02:07:19PM +0000, Julien Thierry wrote: >>> When using VHE, the host needs to clear HCR_EL2.TGE bit in order >>> to interract with guest TLBs, switching from EL2&0 translation regime >>> to EL1&0. >>> >>> However, some non-maskable asynchronous event could happen while TGE is >>> cleared like SDEI. Because of this address translation operations >>> relying on EL2&0 translation regime could fail (tlb invalidation, >>> userspace access, ...). >> >> Why would an NMI context need to access user space? (just curious what >> breaks exactly without this patch; otherwise it looks fine) > > If I remember correctly, the SDEI interrupt might perform cache > maintenance with EL2&0 translation regime, but James can probably give > more detail (or correct me if I'm wrong). Yup, spot on. The APEI driver has to map/unmap memory using the fixmap. If it interrupts a guest, the TLB maintenance would affect EL1&0 instead. > Otherwise, if we decide to use the pseudo NMI for profiling with perf, I > believe the perf interrupt can access user space (although I'm not > completely sure whether that might be to record profiling data in > buffers shared with user space or something else). It does a stack walk, I think its the PERF_SAMPLE_CALLCHAIN feature, and the code is: arch/arm64/kernel/perf_callchain.c::user_backtrace() Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel