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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=RlhK2hG/xqEyHsZ8M+NAPeUgfJW5DDIvr4KRiZYdLrs=; b=tRU39Se8YQosT/ kAEFXTHKKSqLZAnP1vJw9f94xaFd7H1cc5Y5zQt/AX8FRk9KduQOr4nIGBG4bgvXqilFSbXXtgj0y RvvRtWJ/E2zr3kyBdF4UnAZKKcCk3JrFV8XwaA78JNkktkwq5THSZtn7SWLSC8f+610q1F6P6/1QN xHEafmZOGkdqBWQVtrJzOjZ4pal6tds/EJLM6sK/UY+uwGS5qLDum0H69JXj3j3lelWdnzUwNrfWw p039zQDuBMcg/scpvSWqflmAhf8Q6KTGG6tg16PQMkp3cN9KFieHA29kwYTSNOs41poRjqNZShR5D hHaDC77dDxAwbhBHxrdA==; 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 1gXN45-0003Sf-Sv; Thu, 13 Dec 2018 09:13:53 +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 1gXN42-0003AQ-GL for linux-arm-kernel@lists.infradead.org; Thu, 13 Dec 2018 09:13:52 +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 A351580D; Thu, 13 Dec 2018 01:13:39 -0800 (PST) Received: from [10.1.197.36] (e112298-lin.cambridge.arm.com [10.1.197.36]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CFB563F6A8; Thu, 13 Dec 2018 01:13:37 -0800 (PST) Subject: Re: [PATCH 1/6] arm64: kpti: move check for non-vulnerable CPUs to a function To: Jeremy Linton , linux-arm-kernel@lists.infradead.org References: <20181206234408.1287689-1-jeremy.linton@arm.com> <20181206234408.1287689-2-jeremy.linton@arm.com> From: Julien Thierry Message-ID: <1c6081ca-8335-759f-3f49-f8fa60b2fb90@arm.com> Date: Thu, 13 Dec 2018 09:13:36 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181206234408.1287689-2-jeremy.linton@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181213_011350_599186_FB13BB80 X-CRM114-Status: GOOD ( 19.70 ) 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, suzuki.poulose@arm.com, marc.zyngier@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, ykaukab@suse.de, dave.martin@arm.com, shankerd@codeaurora.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, On 06/12/2018 23:44, Jeremy Linton wrote: > From: Mian Yousaf Kaukab > > Add is_meltdown_safe() which is a whitelist of known safe cores. > > Signed-off-by: Mian Yousaf Kaukab > [Moved location of function] > Signed-off-by: Jeremy Linton > --- > arch/arm64/kernel/cpufeature.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index aec5ecb85737..242898395f68 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -908,8 +908,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) > #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ > > -static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > - int scope) > +static bool is_cpu_meltdown_safe(void) > { > /* List of CPUs that are not vulnerable and don't need KPTI */ > static const struct midr_range kpti_safe_list[] = { > @@ -917,6 +916,16 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), > { /* sentinel */ } > }; > + /* Don't force KPTI for CPUs that are not vulnerable */ This is really a nit, but that comment would make more sense where is_cpu_meltdown_safe() is called since unmap_kernel_at_el0 is the one deciding whether to apply KPTI, is_cpu_meltdown_safe() just states whether the core is safe of not. Otherwise: Reviewed-by: Julien Thierry Cheers, Julien > + if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) > + return true; > + > + return false; > +} > + > +static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > + int scope) > +{ > char const *str = "command line option"; > > /* > @@ -940,8 +949,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) > return true; > > - /* Don't force KPTI for CPUs that are not vulnerable */ > - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) > + if (is_cpu_meltdown_safe()) > return false; > > /* Defer to CPU feature registers */ > -- Julien Thierry _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel