From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvd/8AMb+KJrV2cWVT01+BUoDojhZbraau7YuOf+tW3TOt2y4MmrnQBqbDFE7J7weTu4HuD ARC-Seal: i=1; a=rsa-sha256; t=1521228612; cv=none; d=google.com; s=arc-20160816; b=JAggwjNc5E5ASwHMXcO/go52grJJEK8WZLpLl8BHS8J5E3Wst8anXDjPxzipXEhKm8 Ja/LiEKo4NLmuS0B8gSubLzLzGgAAf3Wo8bbbQdgA7aMXSDWur5nEy/Kbw0uPqtharqT qdO4RU8SWMJNEq3HhpbcPbpwIXPqu4TyhqoWJnif5523xJl35Qe7e7VKvHnjrVphZ9dT oWhzDWfD1rmcktU5U6m0Jfnvd2tZmCiJCyI4VdomrxI7jFedcCsisWstNsXhdpIRM8pb DMTDA7RssVOOmGoibtfC9uR7xz8CLX+5ABZLj1FtBJFmixz2ogJNKtA371Fbw6/xignD zE5w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=Bb0yXFnnfWeJuIId9R35QPqjkYX4kDq1nzrBg7fvyCM=; b=d4gM55uIHc6dU08s2V4DXa+jBcVqvjJOx6Tg/jfEXjL95cBZCuUkn7Emz1v6UBJ25P s8NL0NF+/zRbFbLCF3f2Mg1ZzVMV2HutV/nMZ3WZRtBLpSuyXLG3/WxksodGDuFfxzdz kZJjcJ8U9Mtx/pY46dXDz5EoHprkDu+6s+VOCds6YgQ672MUwFtvKE/PzdFVbEM7Nlwm cyCGgOrQbn68n7hK+gG5NrLiI80q2MVfhd4cjNl5WrUmrCa4FeKTxvSNNuTmpNoZPDWQ tieb0Fzw3Q7zHmg3o7hxN2UROmzU7Tlc8qqbuPSqel+WqAOeoEaPl9J4DwFx3Jhaw+i8 sRJw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=d648/3Kd; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=d648/3Kd; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 34/35] x86/mm/pti: Add Warning when booting on a PCID capable CPU Date: Fri, 16 Mar 2018 20:29:52 +0100 Message-Id: <1521228593-3820-35-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521228593-3820-1-git-send-email-joro@8bytes.org> References: <1521228593-3820-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595123814075618195?= X-GMAIL-MSGID: =?utf-8?q?1595123814075618195?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Joerg Roedel Warn the user in case the performance can be significantly improved by switching to a 64-bit kernel. Suggested-by: Andy Lutomirski Signed-off-by: Joerg Roedel --- arch/x86/mm/pti.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 3ffd923..8f5aa0d 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -385,6 +385,22 @@ void __init pti_init(void) pr_info("enabled\n"); +#ifdef CONFIG_X86_32 + if (boot_cpu_has(X86_FEATURE_PCID)) { + /* Use printk to work around pr_fmt() */ + printk(KERN_WARNING "\n"); + printk(KERN_WARNING "************************************************************\n"); + printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n"); + printk(KERN_WARNING "** **\n"); + printk(KERN_WARNING "** You are using 32-bit PTI on a 64-bit PCID-capable CPU. **\n"); + printk(KERN_WARNING "** Your performance will increase dramatically if you **\n"); + printk(KERN_WARNING "** switch to a 64-bit kernel! **\n"); + printk(KERN_WARNING "** **\n"); + printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n"); + printk(KERN_WARNING "************************************************************\n"); + } +#endif + pti_clone_user_shared(); pti_clone_entry_text(); pti_setup_espfix64(); -- 2.7.4