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=-12.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 7F6B7C4320A for ; Thu, 12 Aug 2021 19:05:04 +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 4878B610A5 for ; Thu, 12 Aug 2021 19:05:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4878B610A5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=ZX6fBk1QFUQgrsTxNyQTVD1e+TJF40Sa7D3bjvxC9fM=; b=RZd3Wk3TkLcSQD n5ZfqBTodt1Y0ofRTCPjvRQvCKnlihIAZ9Lj3MyYuxINHJzjWj169T6lgpsIi3uijI2onzicEmPKp Q1SblMYNEnPtoWVIyP4upobnmiEt3D7o5WMAozdjhlaoxlpXyWJxH4VySp220SaroubPZlFe05FRD rcmzHXao4RiJMBHTiOLVDZ3NsaQxBX7uqfEGcjjlhSQPmloz0iReJb9OBdr5AC2R+r2XIVBpOyWR4 Eo3CSLB9aQAzpIMNes1b+IM17vKWDDJUPsCDEKf/E75R5ePsFuOC96LOAMrkArcXgOG7I3M/bg+0a RjBaABYayzRglhDcJ0lA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEFyb-00Axde-W5; Thu, 12 Aug 2021 19:02:50 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEFyM-00AxY6-Es for linux-arm-kernel@lists.infradead.org; Thu, 12 Aug 2021 19:02:36 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E862A6108C; Thu, 12 Aug 2021 19:02:33 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mEFyJ-004c9r-W0; Thu, 12 Aug 2021 20:02:32 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, kernel-team@android.com Subject: [PATCH 0/5] arm64: Survival kit for SCR_EL3.HCE==0 conditions Date: Thu, 12 Aug 2021 20:02:08 +0100 Message-Id: <20210812190213.2601506-1-maz@kernel.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, zajec5@gmail.com, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, ardb@kernel.org, f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_120234_576531_9836C189 X-CRM114-Status: GOOD ( 18.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Anyone vaguely familiar with the ARMv8 architecture would quickly understand that entering the kernel at EL2 without enabling the HVC instruction is... living dangerously. But as it turns out [0], there is a whole range of (*cough*) "high quality" (*cough*) Broadcom systems out there configured exactly like that. If you are speechless, I'm right with you. These machines have stopped being able to boot an upstream kernel since 5.12, where we changed the way we switch from nVHE to VHE, as this relies on the HVC instruction being usable... It is also worth noting that these systems have never been able to use KVM. Or kexec. This small series addresses the issue by detecting an UNDEFing HVC in a fairly controlled environment, and in this case pretend that we have booted at EL1. It also documents the requirement for SCR_EL3.HCE to be set to *1* if the kernel is entered at EL2. Turns out that we really have to state the obvious. This has been tested on a FVP model with a hacked-up boot-wrapper. Note that I really don't think any of this is -stable material, except maybe for the documentation. It isn't 5.14 material either. Best case, this is 5.15, or maybe even later. If ever. M. (drink required) [0] https://lore.kernel.org/r/53f3a2d2-22f8-edee-2507-d41a4090dad7@gmail.com Marc Zyngier (5): arm64: Directly expand __init_el2_nvhe_prepare_eret where needed arm64: Handle UNDEF in the EL2 stub vectors arm64: Detect disabled HVC early arm64: Warn on booting at EL2 with HVC disabled arm64: Document the requirement for SCR_EL3.HCE Documentation/arm64/booting.rst | 5 +++++ arch/arm64/include/asm/el2_setup.h | 6 ------ arch/arm64/include/asm/virt.h | 10 +++++++++ arch/arm64/kernel/head.S | 34 ++++++++++++++++++++++++++++++ arch/arm64/kernel/hyp-stub.S | 19 ++++++++++++++++- arch/arm64/kernel/smp.c | 3 +++ 6 files changed, 70 insertions(+), 7 deletions(-) -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel