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 BDE15C00140 for ; Mon, 15 Aug 2022 10:21:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231722AbiHOKU7 (ORCPT ); Mon, 15 Aug 2022 06:20:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242509AbiHOKUq (ORCPT ); Mon, 15 Aug 2022 06:20:46 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B873A6354; Mon, 15 Aug 2022 03:20:45 -0700 (PDT) Date: Mon, 15 Aug 2022 10:20:42 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1660558844; 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=tGdrZ1nVudr21xNYZsrDmg+Ws1QYXP4nSvy2Q7o0lT8=; b=AiMOFrIGCxmphCTQ3sp6tZwJ4BJ5zmRB4WH+DKz8IZG8nREMq7tw6Vud6fMTtjpKAoBM+x 8bzA4HAClGlPVd5hB99IgSssTmdX6L7vBSny1L6FGCpyJMP+SdM43lT8WJUx408HuT3Qro T63PSPCvqTCFYObT1bRwIxgEX5j4P+soDxiZaLSaBPmtYd2cXUSKqfBEMgSodCW/HzH5wf TRajIspjsKbLhdG27YT7ypOTsg6UOe4n0q9YSJDQBNE2c6NvLs7mzoxJaVjR0KDT5uRcaT 2jbPw4p5ivtCSNxF0g207VGdwXax9cxt+FNfltAeBP89Ki7y6YqHDRzTJnHVug== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1660558844; 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=tGdrZ1nVudr21xNYZsrDmg+Ws1QYXP4nSvy2Q7o0lT8=; b=uZa1sPnMQs0uk0Y+3N81g26lFphS5wFsJLSuYpXiz9SIq5Z6O6F4l+D0ldaS1+t6tO4f9j ouK9P0fBP5H/RXAA== From: "tip-bot2 for Jan Beulich" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/PAT: Have pat_enabled() properly reflect state when running on Xen Cc: Jan Beulich , Borislav Petkov , Ingo Molnar , , Juergen Gross , Lucas De Marchi , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <9385fa60-fa5d-f559-a137-6608408f88b0@suse.com> References: <9385fa60-fa5d-f559-a137-6608408f88b0@suse.com> MIME-Version: 1.0 Message-ID: <166055884287.401.612271624942869534.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 72cbc8f04fe2fa93443c0fcccb7ad91dfea3d9ce Gitweb: https://git.kernel.org/tip/72cbc8f04fe2fa93443c0fcccb7ad91dfea3d9ce Author: Jan Beulich AuthorDate: Thu, 28 Apr 2022 16:50:29 +02:00 Committer: Borislav Petkov CommitterDate: Mon, 15 Aug 2022 10:51:23 +02:00 x86/PAT: Have pat_enabled() properly reflect state when running on Xen After commit ID in the Fixes: tag, pat_enabled() returns false (because of PAT initialization being suppressed in the absence of MTRRs being announced to be available). This has become a problem: the i915 driver now fails to initialize when running PV on Xen (i915_gem_object_pin_map() is where I located the induced failure), and its error handling is flaky enough to (at least sometimes) result in a hung system. Yet even beyond that problem the keying of the use of WC mappings to pat_enabled() (see arch_can_pci_mmap_wc()) means that in particular graphics frame buffer accesses would have been quite a bit less optimal than possible. Arrange for the function to return true in such environments, without undermining the rest of PAT MSR management logic considering PAT to be disabled: specifically, no writes to the PAT MSR should occur. For the new boolean to live in .init.data, init_cache_modes() also needs moving to .init.text (where it could/should have lived already before). [ bp: This is the "small fix" variant for stable. It'll get replaced with a proper PAT and MTRR detection split upstream but that is too involved for a stable backport. - additional touchups to commit msg. Use cpu_feature_enabled(). ] Fixes: bdd8b6c98239 ("drm/i915: replace X86_FEATURE_PAT with pat_enabled()") Signed-off-by: Jan Beulich Signed-off-by: Borislav Petkov Acked-by: Ingo Molnar Cc: Cc: Juergen Gross Cc: Lucas De Marchi Link: https://lore.kernel.org/r/9385fa60-fa5d-f559-a137-6608408f88b0@suse.com --- arch/x86/mm/pat/memtype.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c index d5ef64d..66a209f 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -62,6 +62,7 @@ static bool __read_mostly pat_bp_initialized; static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT); +static bool __initdata pat_force_disabled = !IS_ENABLED(CONFIG_X86_PAT); static bool __read_mostly pat_bp_enabled; static bool __read_mostly pat_cm_initialized; @@ -86,6 +87,7 @@ void pat_disable(const char *msg_reason) static int __init nopat(char *str) { pat_disable("PAT support disabled via boot option."); + pat_force_disabled = true; return 0; } early_param("nopat", nopat); @@ -272,7 +274,7 @@ static void pat_ap_init(u64 pat) wrmsrl(MSR_IA32_CR_PAT, pat); } -void init_cache_modes(void) +void __init init_cache_modes(void) { u64 pat = 0; @@ -313,6 +315,12 @@ void init_cache_modes(void) */ pat = PAT(0, WB) | PAT(1, WT) | PAT(2, UC_MINUS) | PAT(3, UC) | PAT(4, WB) | PAT(5, WT) | PAT(6, UC_MINUS) | PAT(7, UC); + } else if (!pat_force_disabled && cpu_feature_enabled(X86_FEATURE_HYPERVISOR)) { + /* + * Clearly PAT is enabled underneath. Allow pat_enabled() to + * reflect this. + */ + pat_bp_enabled = true; } __init_cache_modes(pat);