From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) (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 910ED1494B3 for ; Thu, 23 Jan 2025 17:24:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737653080; cv=none; b=SdbS2ijwSBSo2YX+alRPJs8CDIBNWJ/qjsaGQwpQtJgFDEKlc2FbagEkBwJk8vU+KyPzcnOEDXcmHKvJdIbrcCGguGSkzvvKTtWXa/aqIsQjRjv9KSXigEWz3CI78AwmufqlINUveDBfwGLh/0/wIzADrxsL1pkECxXleNnlchE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737653080; c=relaxed/simple; bh=eGrXreTvumz+NgRHWBc9LF9mtVApae5j+DCBTgEQnKg=; h=Subject:To:Cc:From:Date:References:In-Reply-To:Message-Id; b=r5XpM1hbaRIKZLfwG61glwEGQgmU/eK7Qqa8b7B670wEGud5cHymMbfbjrkuFR/OmAXVcRsyp3mcC7vWiZg3DRO0VlKbGSobMYRNiTlC0ZFfLVUtSw7pXzIP1OM/QYh7XtyeINZOnQv7Tx+yXXyzhHO8/x7z/6S2gE36HGNLAIg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=MpFDFgiK; arc=none smtp.client-ip=192.198.163.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="MpFDFgiK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1737653078; x=1769189078; h=subject:to:cc:from:date:references:in-reply-to: message-id; bh=eGrXreTvumz+NgRHWBc9LF9mtVApae5j+DCBTgEQnKg=; b=MpFDFgiKTGS+72U0VsWtTl5UZ536lnDCAJLMUyPAbg2xB/4/Rh/W9KVb OizOeJLvdNcq/F9AecuDmOKezQWminWGSZLpjG5lkqdqsD0kFew4et44H 81Cd3izwPpMI/nJ3OqBZeP7k/rjp4sUb7NGdWU3xjxTOyi1NoqylMqGks hty25fzt4lEaQUqQgs9E72WCU4b7dlb4vDoOmQV8CdM2UrvmsDcabye0s XRTDbGJ/zqMqPowwOo5KnQHu/bkkDGs6t9oN62T6cKpdqRft1RqRqJWrt ZVdzqpT/2SaZzTpUCuzIHP1rlE3z5sJfZOoZtJAzVZ4Hx+SDuqPy21k3p w==; X-CSE-ConnectionGUID: lY+yo8CET1munYYaUbhPmA== X-CSE-MsgGUID: 2bK0RUnaQBuZULg414IvIw== X-IronPort-AV: E=McAfee;i="6700,10204,11314"; a="49583840" X-IronPort-AV: E=Sophos;i="6.12,310,1728975600"; d="scan'208";a="49583840" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jan 2025 09:24:32 -0800 X-CSE-ConnectionGUID: w+vWTnphRhafr87/51X0jg== X-CSE-MsgGUID: bXcXvRuwR8ajTpm4WXq0Gg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.13,229,1732608000"; d="scan'208";a="107649966" Received: from davehans-spike.ostc.intel.com (HELO localhost.localdomain) ([10.165.164.11]) by fmviesa008.fm.intel.com with ESMTP; 23 Jan 2025 09:24:32 -0800 Subject: [RFC][PATCH 2/8] x86/mm: Always "broadcast" PMD setting operations To: linux-kernel@vger.kernel.org Cc: x86@kernel.org,tglx@linutronix.de,bp@alien8.de,joro@8bytes.org,luto@kernel.org,peterz@infradead.org,kirill.shutemov@linux.intel.com,rick.p.edgecombe@intel.com,jgross@suse.com,Dave Hansen From: Dave Hansen Date: Thu, 23 Jan 2025 09:24:32 -0800 References: <20250123172428.D6D8C8D9@davehans-spike.ostc.intel.com> In-Reply-To: <20250123172428.D6D8C8D9@davehans-spike.ostc.intel.com> Message-Id: <20250123172432.32468487@davehans-spike.ostc.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: From: Dave Hansen Kernel PMDs can either be shared across processes or private to a process. On 64-bit, they are always shared. 32-bit non-PAE hardware does not have PMDs, but the kernel logically squishes them into the PGD and treats them as private. Here are the four cases: 64-bit: Shared 32-bit: non-PAE: Private 32-bit: PAE+ PTI: Private 32-bit: PAE+noPTI: Shared Note that 32-bit is all "Private" except for PAE+noPTI being an oddball. The 32-bit+PAE+noPTI case will be made like the rest of 32-bit shortly. But until that can be done, temporarily treat the 32-bit+PAE+noPTI case as Private. This will do unnecessary walks across pgd_list and unnecessary PTE setting but should be otherwise harmless. Signed-off-by: Dave Hansen --- b/arch/x86/mm/pat/set_memory.c | 2 +- b/arch/x86/mm/pgtable.c | 11 +++-------- 2 files changed, 4 insertions(+), 9 deletions(-) diff -puN arch/x86/mm/pat/set_memory.c~always-sync-kernel-mapping-updates arch/x86/mm/pat/set_memory.c --- a/arch/x86/mm/pat/set_memory.c~always-sync-kernel-mapping-updates 2025-01-23 09:20:50.674347666 -0800 +++ b/arch/x86/mm/pat/set_memory.c 2025-01-23 09:20:50.678347810 -0800 @@ -840,7 +840,7 @@ static void __set_pmd_pte(pte_t *kpte, u /* change init_mm */ set_pte_atomic(kpte, pte); #ifdef CONFIG_X86_32 - if (!SHARED_KERNEL_PMD) { + { struct page *page; list_for_each_entry(page, &pgd_list, lru) { diff -puN arch/x86/mm/pgtable.c~always-sync-kernel-mapping-updates arch/x86/mm/pgtable.c --- a/arch/x86/mm/pgtable.c~always-sync-kernel-mapping-updates 2025-01-23 09:20:50.674347666 -0800 +++ b/arch/x86/mm/pgtable.c 2025-01-23 09:20:50.678347810 -0800 @@ -136,18 +136,13 @@ static void pgd_ctor(struct mm_struct *m KERNEL_PGD_PTRS); } - /* list required to sync kernel mapping updates */ - if (!SHARED_KERNEL_PMD) { - pgd_set_mm(pgd, mm); - pgd_list_add(pgd); - } + /* List used to sync kernel mapping updates */ + pgd_set_mm(pgd, mm); + pgd_list_add(pgd); } static void pgd_dtor(pgd_t *pgd) { - if (SHARED_KERNEL_PMD) - return; - spin_lock(&pgd_lock); pgd_list_del(pgd); spin_unlock(&pgd_lock); _