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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 15AFBC433DB for ; Tue, 29 Dec 2020 17:05:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DED7A207C9 for ; Tue, 29 Dec 2020 17:05:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726281AbgL2RFE (ORCPT ); Tue, 29 Dec 2020 12:05:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726230AbgL2RFD (ORCPT ); Tue, 29 Dec 2020 12:05:03 -0500 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B8A0C0613D6 for ; Tue, 29 Dec 2020 09:04:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FhCXE7slKDeIxopRDJZcSEDk1dcwjpLiihzO8A1DLYI=; b=AYhIRsKhcTRQMcw8YcP2xAlQP ZJ7L1gjPikShRcrMBIm+phM9DzBwgyb0v11vAj4qepLHcuoQCQ/NlJtACcoE85OrXpInyCAaBMdSK Td2Oykho2vQPWR407CJe6NN7DvuTOvf4sZVp/IqpijQq4Ql19Eth2DJJNXKEADW40L9qBSdzqth9B EFsTsXoylISXM1eFdZlh/4udhreDKyRgx2I56jZQ5P2Y9KY1s7hN0PXwTmxKSY1hBY9a8Zin52g22 EXWzcXymEZ+3X3p4nwONwEJSJrHE8RtZQ5JTPQcg5BmKCwqOrdP16VOMLuXW4iPmd675vwWZ8D84Y UNTNCYeMQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44878) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kuIPv-0005F2-Sw; Tue, 29 Dec 2020 17:04:16 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kuIPs-0001ON-Dm; Tue, 29 Dec 2020 17:04:12 +0000 Date: Tue, 29 Dec 2020 17:04:12 +0000 From: Russell King - ARM Linux admin To: David Brazdil Cc: kvmarm@lists.cs.columbia.edu, Mark Rutland , Lorenzo Pieralisi , Suzuki K Poulose , Marc Zyngier , Sudeep Holla , linux-kernel@vger.kernel.org, James Morse , linux-arm-kernel@lists.infradead.org, Catalin Marinas , kernel-team@android.com, Will Deacon , Julien Thierry Subject: Re: [PATCH] KVM: arm64: Allow PSCI SYSTEM_OFF/RESET to return Message-ID: <20201229170412.GN1551@shell.armlinux.org.uk> References: <20201229160059.64135-1-dbrazdil@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201229160059.64135-1-dbrazdil@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 29, 2020 at 04:00:59PM +0000, David Brazdil wrote: > The KVM/arm64 PSCI relay assumes that SYSTEM_OFF and SYSTEM_RESET should > not return, as dictated by the PSCI spec. However, there is firmware out > there which breaks this assumption, leading to a hyp panic. Make KVM > more robust to broken firmware by allowing these to return. Are you sure you should just return? We've had issues in the past with Linux reboot(2) that returns to userspace, allowing on 32-bit ARM for example watchdogs to unexpectedly continue being serviced. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!