From nobody Sun May 24 22:42:32 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 56FCF3803DC; Wed, 20 May 2026 21:25:44 +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=1779312345; cv=none; b=BBeHy6WCep9TusZsVTuKaNevevxKV2IFN7tNysOx1NVoevBW/QMiqBKmI40k+U0nF2M+F2BY4ulXW86rJetieNEuc29SCtd3lRtKqmqoExumoMqKHde6h6HHJ0wKKMmk5pvN36Kb6vd4gTyzo6BbDtOL2hZe6L6AFdORcdzv724= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779312345; c=relaxed/simple; bh=xX7Yr4+KFOWnvnCSONhra518Bu/xPPtz3Q6vwOtCBQ0=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=edbuldRFYykQ+eWeNqA7zyN9nqpHoY3ok0TcEV5F2tp2gjLJVQgg1uPEPSxEm/vfjFxS126rMXEi+xWAT3YIPisNVjWhjdLk93HWm9vUkM3XmMzdLm6DxA/i4fQZF+X7k99yae3YJXuatUQP6YQm2437tPEFcgAZlULEBZmcZLE= 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=XaV3q73z; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=m8mQ10jY; 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="XaV3q73z"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="m8mQ10jY" Date: Wed, 20 May 2026 21:25:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1779312342; 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=jEmyDIR+qqzZbFKb8/u9/6a+WtzWIuJmUjp+MvTzzMw=; b=XaV3q73zBiItghAo4HEBzka9HZx4sdsxvH7hnP3YL4m+EQnvAA5aNYF0yl7sP4unGgJCW7 LTXebI4bgmcOkKLW8LV7+5XbD4cWHjZidvXZuts+mSsr2ERKVHvIe4H7g71w/lVT9y76TP Dtk8W1MgUeTYet+a4HjxoQYrOAL4fql+rDA+ZGkRVqF8GLWh9HzsPNY1I1zvvrkIzOd9wJ 2vHCAYux2ViZvBQcXKzffjzCUwchsqT0XyQ9pu9bggi1avj0qALpmHbeRQ+ybRk4M+iWnX H8bQcbim1l4kktlmkMEpBcJACcjUjf8l6gWqYktP2F1C8YQ4I78krcynf7QfbA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1779312342; 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=jEmyDIR+qqzZbFKb8/u9/6a+WtzWIuJmUjp+MvTzzMw=; b=m8mQ10jYrdIXktRf76C4hL/XSyHgbkuzrOPOATRqTCF8zs6kivrKmMwhedS9ioBaxkGHLC 9zwjA5PXiUAiilDA== From: "tip-bot2 for Tom Lendacky" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/mm: Disable broadcast TLB flush when PCID is disabled Cc: Dave Hansen , Tom Lendacky , "Borislav Petkov (AMD)" , Rik van Riel , , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: =?utf-8?q?=3Cb915acfd63e8b2a094fdeb8dc608738072518764=2E1779296?= =?utf-8?q?450=2Egit=2Ethomas=2Elendacky=40amd=2Ecom=3E?= References: =?utf-8?q?=3Cb915acfd63e8b2a094fdeb8dc608738072518764=2E17792964?= =?utf-8?q?50=2Egit=2Ethomas=2Elendacky=40amd=2Ecom=3E?= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <177931234030.711.9297054216841465736.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/urgent branch of tip: Commit-ID: 44126343d58c68adaa8343fbf1c07dd20078c35e Gitweb: https://git.kernel.org/tip/44126343d58c68adaa8343fbf1c07dd20= 078c35e Author: Tom Lendacky AuthorDate: Wed, 20 May 2026 12:00:50 -05:00 Committer: Borislav Petkov (AMD) CommitterDate: Wed, 20 May 2026 14:15:07 -07:00 x86/mm: Disable broadcast TLB flush when PCID is disabled Booting with "nopcid" clears X86_FEATURE_PCID and keeps CR4.PCIDE from being set to one. On AMD CPUs that support INVLPGB, broadcast TLB flushing remains enabled. There are two checks that decide whether the global ASID code runs, mm_global_asid() and consider_global_asid(), that key off of the X86_FEATURE_INVLPGB feature. Once an mm becomes active on more than three CPUs, consider_global_asid() assigns it a global ASID, after which flush_tlb_mm_range() takes the broadcast_tlb_flush() path using a non-zero PCID. Issuing an INVLPGB with a non-zero PCID while CR4.PCIDE is not set results in a #GP: Oops: general protection fault, kernel NULL pointer dereference 0x1: 0000= [#1] SMP NOPTI CPU: 158 UID: 0 PID: 3119 Comm: snap Not tainted 7.1.0-rc3 #1 PREEMPT(ful= l) Hardware name: ... RIP: 0010:broadcast_tlb_flush Code: ... 89 da 48 83 c8 07 <0f> 01 fe eb 08 cc cc cc ... Call Trace: flush_tlb_mm_range ptep_clear_flush wp_page_copy ? _raw_spin_unlock __handle_mm_fault handle_mm_fault do_user_addr_fault exc_page_fault asm_exc_page_fault All processors that support broadcast TLB invalidation also have PCID suppo= rt, so it is only the "nopcid" scenario that is of concern. In this situation j= ust disable the broadcast TLB support using the CPUID dependency support by mak= ing X86_FEATURE_INVLPGB dependent on X86_FEATURE_PCID. [ bp: Massage commit message. ] Fixes: 4afeb0ed1753 ("x86/mm: Enable broadcast TLB invalidation for multi-t= hreaded processes") Suggested-by: Dave Hansen Assisted-by: Claude:claude-opus-4.7 Signed-off-by: Tom Lendacky Signed-off-by: Borislav Petkov (AMD) Acked-by: Rik van Riel Cc: Link: https://patch.msgid.link/b915acfd63e8b2a094fdeb8dc608738072518764.177= 9296450.git.thomas.lendacky@amd.com --- arch/x86/kernel/cpu/cpuid-deps.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-d= eps.c index 146f6f8..99801e8 100644 --- a/arch/x86/kernel/cpu/cpuid-deps.c +++ b/arch/x86/kernel/cpu/cpuid-deps.c @@ -92,6 +92,7 @@ static const struct cpuid_dep cpuid_deps[] =3D { { X86_FEATURE_FRED, X86_FEATURE_LKGS }, { X86_FEATURE_SPEC_CTRL_SSBD, X86_FEATURE_SPEC_CTRL }, { X86_FEATURE_LASS, X86_FEATURE_SMAP }, + { X86_FEATURE_INVLPGB, X86_FEATURE_PCID }, {} }; =20