From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CD84FA373D for ; Fri, 21 Oct 2022 17:20:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231365AbiJURUV (ORCPT ); Fri, 21 Oct 2022 13:20:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231340AbiJURT7 (ORCPT ); Fri, 21 Oct 2022 13:19:59 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9DBC733C9 for ; Fri, 21 Oct 2022 10:19:48 -0700 (PDT) Received: from zn.tnic (p200300ea9733e769329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:9733:e769:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 1716C1EC072C; Fri, 21 Oct 2022 19:19:29 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1666372769; h=from:from: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:in-reply-to:in-reply-to: references:references; bh=ffg5NFO6tKVWSvtqYlp2XGILZ80EHuLep0vwKN4z2rY=; b=ME7+CSalOdpFY8l4MGtCsWwEHn2B8Dt8+LLRPZfDhiJCeR/y9ROe1wTmobgr+mcetr8Sj8 qyLrlUAmcnOU7EZ0BiFoTMaof7nCcPOwOUauWFQwdZBOnwgW4bxKhxDJVNGGddCGl2vPrJ XKUFyYmhyHoviplwhPk2B5aMpwRN4eA= Date: Fri, 21 Oct 2022 19:19:23 +0200 From: Borislav Petkov To: Juergen Gross Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , Dave Hansen , "H. Peter Anvin" Subject: Re: [PATCH v4 03/16] x86/mtrr: replace use_intel() with a local flag Message-ID: References: <20221004081023.32402-1-jgross@suse.com> <20221004081023.32402-4-jgross@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20221004081023.32402-4-jgross@suse.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 04, 2022 at 10:10:10AM +0200, Juergen Gross wrote: > In MTRR code use_intel() is only used in one source file, and the > relevant use_intel_if member of struct mtrr_ops is set only in > generic_mtrr_ops. > > Replace use_intel() with a single flag in cacheinfo.c, which can be set > when assigning generic_mtrr_ops to mtrr_if. This allows to drop > use_intel_if from mtrr_ops, while preparing to support PAT without > MTRR. As another preparation for the PAT/MTRR decoupling use a bit for > MTRR control and one for PAT control. For now set both bits together, > this can be changed later. > > As the new flag will be set only if mtrr_enabled is set, the test for > mtrr_enabled can be dropped at some places. > > At the same time drop the local mtrr_enabled() function and rename > the __mtrr_enabled flag to mtrr_enabled. So, I kinda like your idea about "replace the bool with mtrr_if != NULL" to test whether MTRRs are enabled. IOW, how does this look ontop of yours? At the end of mtrr_bp_init() I need to do some careful dancing but I think this way it is even clearer. I'm pretty sure it can be simplified even more but one thing at a time... Thx. --- diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c index dacb537da126..927b463a22bd 100644 --- a/arch/x86/kernel/cpu/mtrr/mtrr.c +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c @@ -59,7 +59,6 @@ #define MTRR_TO_PHYS_WC_OFFSET 1000 u32 num_var_ranges; -static bool mtrr_enabled; unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES]; static DEFINE_MUTEX(mtrr_mutex); @@ -71,15 +70,17 @@ static const struct mtrr_ops *mtrr_ops[X86_VENDOR_NUM] __ro_after_init; const struct mtrr_ops *mtrr_if; -static void set_mtrr(unsigned int reg, unsigned long base, - unsigned long size, mtrr_type type); - void __init set_mtrr_ops(const struct mtrr_ops *ops) { if (ops->vendor && ops->vendor < X86_VENDOR_NUM) mtrr_ops[ops->vendor] = ops; } +static bool mtrr_enabled(void) +{ + return !!mtrr_if; +} + /* Returns non-zero if we have the write-combining memory type */ static int have_wrcomb(void) { @@ -299,7 +300,7 @@ int mtrr_add_page(unsigned long base, unsigned long size, int i, replace, error; mtrr_type ltype; - if (!mtrr_enabled) + if (!mtrr_enabled()) return -ENXIO; error = mtrr_if->validate_add_page(base, size, type); @@ -447,7 +448,7 @@ static int mtrr_check(unsigned long base, unsigned long size) int mtrr_add(unsigned long base, unsigned long size, unsigned int type, bool increment) { - if (!mtrr_enabled) + if (!mtrr_enabled()) return -ENODEV; if (mtrr_check(base, size)) return -EINVAL; @@ -476,7 +477,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size) unsigned long lbase, lsize; int error = -EINVAL; - if (!mtrr_enabled) + if (!mtrr_enabled()) return -ENODEV; max = num_var_ranges; @@ -536,7 +537,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size) */ int mtrr_del(int reg, unsigned long base, unsigned long size) { - if (!mtrr_enabled) + if (!mtrr_enabled()) return -ENODEV; if (mtrr_check(base, size)) return -EINVAL; @@ -562,7 +563,7 @@ int arch_phys_wc_add(unsigned long base, unsigned long size) { int ret; - if (pat_enabled() || !mtrr_enabled) + if (pat_enabled() || !mtrr_enabled()) return 0; /* Success! (We don't need to do anything.) */ ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true); @@ -750,15 +751,18 @@ void __init mtrr_bp_init(void) } } - if (mtrr_if) { - mtrr_enabled = true; - set_num_var_ranges(mtrr_if == &generic_mtrr_ops); + if (mtrr_enabled()) { + bool use_generic = mtrr_if == &generic_mtrr_ops; + bool mtrr_state_enabled = true; + + set_num_var_ranges(use_generic); init_table(); - if (mtrr_if == &generic_mtrr_ops) { + + if (use_generic) { /* BIOS may override */ - mtrr_enabled = get_mtrr_state(); + mtrr_state_enabled = get_mtrr_state(); - if (mtrr_enabled) { + if (mtrr_state_enabled) { mtrr_bp_pat_init(); memory_caching_control |= CACHE_MTRR | CACHE_PAT; } @@ -767,10 +771,13 @@ void __init mtrr_bp_init(void) changed_by_mtrr_cleanup = 1; mtrr_if->set_all(); } + + if (!mtrr_state_enabled) + mtrr_if = NULL; } } - if (!mtrr_enabled) { + if (!mtrr_enabled()) { pr_info("Disabled\n"); /* @@ -811,7 +818,7 @@ void mtrr_save_state(void) { int first_cpu; - if (!mtrr_enabled) + if (!mtrr_enabled()) return; first_cpu = cpumask_first(cpu_online_mask); @@ -856,7 +863,7 @@ void mtrr_bp_restore(void) static int __init mtrr_init_finialize(void) { - if (!mtrr_enabled) + if (!mtrr_enabled()) return 0; if (memory_caching_control & CACHE_MTRR) { -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette