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=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 4593AC28CBC for ; Wed, 6 May 2020 17:14:17 +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 0DE4A208E4 for ; Wed, 6 May 2020 17:14:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hZISWneK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0DE4A208E4 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=CfJFtQRik4/7oSM5Qbu8nuGWxzTF43XMQ0RV+1VDC80=; b=hZISWneKY+HAQZ kGWxKisMT7AuGEef0we61LQ0Vb/EIkvWaPpcm/EgR33YLju9CVe5qSOqW6djxencK1nbMo0Lrz02G /hsMj+Os7fYJ+3lm5WfCGXZDJnAKlDsDPpchaFmPCNJFXc5rNV0FL8QyQhEWcYdvOcUKpGjgX+EKj JCF8c80zDzWwcx0KQkmbDzh+1LLQ+grz7g3pRqXVtXweNLfrdW7xxFkGmglCKahBSSAZW+uUQrlKh D6NG1lOsZQx7F4Egx4M6Sj+x8HgnyeMbqyk9vhE8KSEIBC43bNxRayqu7T9l7hW2cq0JBdoYOJKi2 V3LFHnUTHWfyOLPJ2Y8A==; 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 1jWNce-0000oN-2z; Wed, 06 May 2020 17:14:16 +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 1jWNcb-0000ny-NR for linux-arm-kernel@lists.infradead.org; Wed, 06 May 2020 17:14:15 +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 CFDFF1FB; Wed, 6 May 2020 10:14:02 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 07F113F71F; Wed, 6 May 2020 10:14:00 -0700 (PDT) Date: Wed, 6 May 2020 18:13:50 +0100 From: Catalin Marinas To: Amit Daniel Kachhap Subject: Re: [PATCH v2 3/4] arm64: cpufeature: Modify address authentication cpufeature to exact Message-ID: <20200506171350.GH2878@gaia> References: <1586842314-19527-1-git-send-email-amit.kachhap@arm.com> <1586842314-19527-4-git-send-email-amit.kachhap@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1586842314-19527-4-git-send-email-amit.kachhap@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200506_101413_813845_84722BB2 X-CRM114-Status: GOOD ( 17.49 ) 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 , Kees Cook , Suzuki K Poulose , Kristina Martsenko , Mark Brown , James Morse , Vincenzo Frascino , Will Deacon , Dave Martin , 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 Tue, Apr 14, 2020 at 11:01:53AM +0530, Amit Daniel Kachhap wrote: > This patch modifies the address authentication cpufeature type to EXACT > from earlier LOWER_SAFE as the different configurations added for Armv8.6 > enhanced PAC have different behaviour and there is no tunable to enable the > lower safe versions. The safe value is set as 0. > > After this change, if there is any variation in configurations in secondary > cpus from boot cpu then those cpus are marked tainted. The KVM guests may > completely disable address authentication if there is any such variations > detected. > > Signed-off-by: Amit Daniel Kachhap > --- > arch/arm64/kernel/cpufeature.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 08795025409c..599b03df2f93 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -154,9 +154,9 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = { > ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_FCMA_SHIFT, 4, 0), > ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_JSCVT_SHIFT, 4, 0), > ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH), > - FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_API_SHIFT, 4, 0), > + FTR_STRICT, FTR_EXACT, ID_AA64ISAR1_API_SHIFT, 4, 0), > ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH), > - FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_APA_SHIFT, 4, 0), > + FTR_STRICT, FTR_EXACT, ID_AA64ISAR1_APA_SHIFT, 4, 0), > ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_DPB_SHIFT, 4, 0), > ARM64_FTR_END, Is this sufficient? If we have the boot CPU already enabling the ptrauth and we get a secondary CPU with a different ISAR1 field that matches the address auth in cpufeature.c, we still allow it to boot. We no longer report the feature to the user system_supports_address_auth() is true while system_supports_generic_auth() would be false as it checks the sanitised feature registers. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel