From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49yzYoSb1jKihVZ8dV2Cv2memNK/6g4LbdDoklfYytprF6VI6q14wyGJiSqEft0NTJR9ERz ARC-Seal: i=1; a=rsa-sha256; t=1523892352; cv=none; d=google.com; s=arc-20160816; b=qRQQbUYEfK/Wbp/zxM8j7EMgzWjtUSKLfHtZ/SAxOMZ91fhMksBKslFP+VyQO00ejc qBBp2JeTbkHjXy/iwJ4AQG0i+TLx0ibv7tuT7MrOQ/71MlsJ01jGhq8D1ZSMHn8aJ0/Z y4p/WqVmCB59OsHezNliy16m16kkQix063o/EoaJD7Bjm9MqnzfYcrCEcBIWizvZyQcs cG+mWCJFAP5RpM7yKvmcmk9oYSPjv9GghNVFiELFrH7v925gidEzVtlxuas5oIFFKRVN nQFoQFi+QfpEyPmZGObdqCffMwYWlG8WV3yDhWslXrbMfQvv+t66DPyjTtflMdWc2Jut RTZA== 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=n9v3/D9uFnHXbMksWDxOkHcDCOvgQWwinJ14oMwdSPs=; b=lpHdXiwV5DN3N4G6AMyXS0Mdx18ITENe6DchnhVbpgeDTLVemzC4zxMeBSUx7Bnnm+ 0bqCuHf6pEiXZxs+qj7cIuImIOVvAmGKigwvFR3OMfEb8KC4w6gfK7DEld89gsz5EQ4f LVPTTgqcEF7xFfJJ6bVrhpcm0hedrAbHVINy+OG8io1LaoAkJk2JsfMUk+BU/vnONQS8 +60tCXFy08Abm9r5gq2xkNeWe0AKVlCMFKy7rHF4cM9wPhrsqgryRc/EPbA/Cw1UGUYy TYPz7LtEZMT1r+1wASmAZzYe5l3WtbNsF82LjtcMhxyQ4v1cV+/awWCm4VqQ38zT8SVn xeNA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=Igoi0VTB; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 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=Igoi0VTB; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 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 34/35] x86/mm/pti: Add Warning when booting on a PCID capable CPU Date: Mon, 16 Apr 2018 17:25:22 +0200 Message-Id: <1523892323-14741-35-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1523892323-14741-1-git-send-email-joro@8bytes.org> References: <1523892323-14741-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597916947512269715?= X-GMAIL-MSGID: =?utf-8?q?1597916947512269715?= 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 60a1ee0..ad905e0 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