From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4+FvchVCkBTFxiBq8KHoSQp/ksWHuzrHLOT9C/VWLy+qmtVM3iVB4PieNYpYQDzAsL/8XiT ARC-Seal: i=1; a=rsa-sha256; t=1524498481; cv=none; d=google.com; s=arc-20160816; b=x7BLmygTP8ZnV/cX2h0mz4uc5qUsIcSjTSzZMgpcr+fneIhG/siyDH0GTBtUYNHW3R i5oU3mYzl70G3sXRU2/JXAv4bmjpQxMDmqI7Cg5W477GjVaCCSN8709fOdQLSKChjhFP zDeWvjvh3412rHOi03WgD8UdpdjzqS06kFJhMOnlLskQLNdITLVpvbwe+0hS/kHEp3nQ 1Evn7xnU2BtkS2p9oOFclXLCoDsm+FqATm3HdZHmQIkfLiZFNylpT+XtwMXdKrNGkpGZ Q0S8+GkG3TF2hBoFA/GrCtV0vXMqA3sakDgBjwhxZiAm/g2FUQkzlRatMkzVQshlo8DP 7AGg== 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=PnY2xhffs00kB/6OhfVYGzzrUTrH5jJhTsbd3ccvbQE=; b=o4oQ6Huw8ZUiF74kGKAFLjHvley2N0uZw8eXpykf5cIR1F2udLhXnZcSSuz6kxk5A6 qEtgt/MvShw6sDrAcHSH26+VxyfR9J/lNzc7SW6b1Qyskf/EQURlxm/mitNbki7oQqGS 9X2WAOA14mvVogw8f4FtMxVDdDZ/Plxz94b8o27EgxwOW0RXM5rx/j4/aJnYVpnEDweV AtOQT1EmH/5MsLe0Prc4D15a2EYBEdFboM4dAT0NwBR/tbcxGRcK+wqwvxOrOdVeE9zS /0al7M/UIYdvJ1doJtO0NUKZ4GFUJh1jinOaNVVS3dkJc8X0WZkqlukkj2g84ao5nzK0 DMog== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=SqBwIYlP; 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=SqBwIYlP; 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 , "David H . Gutteridge" , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 36/37] x86/mm/pti: Add Warning when booting on a PCID capable CPU Date: Mon, 23 Apr 2018 17:47:39 +0200 Message-Id: <1524498460-25530-37-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1524498460-25530-1-git-send-email-joro@8bytes.org> References: <1524498460-25530-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598552519649623749?= X-GMAIL-MSGID: =?utf-8?q?1598552519649623749?= 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 e3059bb0..0ab41fb 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -497,6 +497,22 @@ 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(); /* Undo all global bits from the init pagetables in head_64.S: */ -- 2.7.4