From nobody Mon Apr 6 09:15:10 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBBDE332918; Thu, 19 Mar 2026 21:59:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773957564; cv=none; b=SRS31KZp06SPxW5LdN8909T4t/igD28bOA0JwebJ+geDd9d2MLCeF6KfAHEQw3mqgyGHMrD+w0mWCLn9SCKEVGIzPWu0xq7J6KBJNAXphsEQDR3d7A+OJpyFqH/7ge5N5rmBGr5maZrTYbn+YXJgWV2lHBrpnDrvv+F5bzZYJTk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773957564; c=relaxed/simple; bh=I2KGc2PrYJZJn8/BJ9AvJHD2Fh7pHsdFjLe5zqX8w/w=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=CZ6bi16YNPHgtRqrJpbHjZcDMQNLEDQJQdhN2iGuTFPK3rQxUyrsx2eGNc6+ltGs4I6N5RCZP/Ib9RZpBD86pQdidi0f2WLr+TXXlRerUtlDSETd3DTPyCwFQOJ6DEl9AfjB069WJ3FggHEFHGMiHyFOnAElUgGrIUV0g5KjKqs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=uM8SwrKy; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=li4C6guK; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="uM8SwrKy"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="li4C6guK" Date: Thu, 19 Mar 2026 21:59:19 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1773957560; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GhPsxBZyIyhArmADbYUUtb42hDZ/LRVEp9YNfE4SaBE=; b=uM8SwrKyGSIcybkys1nnVbSdx3+uV+bQxY+n0deoEfKKJfl/lz0Hs8zui9nEbQBcf5DV8H GWcrOmcWvDFlBblrHQXTh+sJGWWWwZ+f7rjSKLVtwnoYrPCUiiZ2eyvqsfuebiijk1WB9B wqR8O2SAvLpz4HPXioHRsZAusdifnGqbZeHZ2ODUbFdUepiExnRTxCkJBT7Ygere53p+os WqOOqBu4ekoiKzzSlk9MbbLxDz0uojBvKgJbgkal3ZHu3CRqdKKuRGOi4D80FEqWlL8Dbp Agb0X2dUJqPN/XBVFnLfk4nxdQ9KfK9WoAQbBVBBahQ1feEyhrKlegMcTtFhPQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1773957560; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GhPsxBZyIyhArmADbYUUtb42hDZ/LRVEp9YNfE4SaBE=; b=li4C6guK2fBNf1MtCZ83ig4uZ64bWK6ZwdWTz1HfCn8FPgjMMAzIm+E2HkgOBFHeW2qqaU yOEzAlm9f8YOPmDg== From: "tip-bot2 for Sohil Mehta" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/cpu] x86/cpu: Remove LASS restriction on vsyscall emulation Cc: Sohil Mehta , Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260305214026.3887452-6-sohil.mehta@intel.com> References: <20260305214026.3887452-6-sohil.mehta@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <177395755928.1647592.15989716255105562299.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 0e2a0cb1bf436a3979f3bf93e3b7fede5d93f730 Gitweb: https://git.kernel.org/tip/0e2a0cb1bf436a3979f3bf93e3b7fede5= d93f730 Author: Sohil Mehta AuthorDate: Thu, 05 Mar 2026 13:40:26 -08:00 Committer: Dave Hansen CommitterDate: Thu, 05 Mar 2026 13:49:26 -08:00 x86/cpu: Remove LASS restriction on vsyscall emulation Vsyscall emulation has two modes of operation: XONLY and EMULATE. The default XONLY mode is now supported with a LASS-triggered #GP. OTOH, LASS is disabled if someone requests the deprecated EMULATE mode via the vsyscall=3Demulate command line option. So, remove the restriction on LASS when the overall vsyscall emulation support is compiled in. As a result, there is no need for setup_lass() anymore. LASS is enabled by default through a late_initcall(). Signed-off-by: Sohil Mehta Signed-off-by: Dave Hansen Reviewed-by: Dave Hansen Link: https://patch.msgid.link/20260305214026.3887452-6-sohil.mehta@intel.c= om --- arch/x86/kernel/cpu/common.c | 15 --------------- 1 file changed, 15 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 3557f0e..02472fc 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -406,20 +406,6 @@ out: cr4_clear_bits(X86_CR4_UMIP); } =20 -static __always_inline void setup_lass(struct cpuinfo_x86 *c) -{ - if (!cpu_feature_enabled(X86_FEATURE_LASS)) - return; - - /* - * Legacy vsyscall page access causes a #GP when LASS is active. - * Disable LASS because the #GP handler doesn't support vsyscall - * emulation. - */ - if (IS_ENABLED(CONFIG_X86_VSYSCALL_EMULATION)) - setup_clear_cpu_cap(X86_FEATURE_LASS); -} - static int enable_lass(unsigned int cpu) { cr4_set_bits(X86_CR4_LASS); @@ -2061,7 +2047,6 @@ static void identify_cpu(struct cpuinfo_x86 *c) setup_smep(c); setup_smap(c); setup_umip(c); - setup_lass(c); =20 /* Enable FSGSBASE instructions if available. */ if (cpu_has(c, X86_FEATURE_FSGSBASE)) {