From patchwork Mon Dec 28 12:47:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 354419 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE148C433E9 for ; Mon, 28 Dec 2020 16:09:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA9A420719 for ; Mon, 28 Dec 2020 16:09:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388847AbgL1QI7 (ORCPT ); Mon, 28 Dec 2020 11:08:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:53812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388848AbgL1NZJ (ORCPT ); Mon, 28 Dec 2020 08:25:09 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9DFF0207C9; Mon, 28 Dec 2020 13:24:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609161868; bh=pc25Ij03UZW4qCVFFXZAtLTJbIiKya4ecYPlYuRCOVk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yLxoyw6wX77QOZF+XSQ1Xy8KH09gePj65iKNp+0wOrhfood5UIXb+3AqIqRns6oWG tpAcRaHJfL9LsS2ZqludYnYs/hMwhF94DPiG6lzlkvXfZyBDK3J5PRTcvukWSZ9MQJ D9mw1+Ca5GVU4GyRY0wLve5fy5BidY0epgySb+5I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Woodhouse , Thomas Gleixner , Sasha Levin Subject: [PATCH 4.19 109/346] x86/apic: Fix x2apic enablement without interrupt remapping Date: Mon, 28 Dec 2020 13:47:08 +0100 Message-Id: <20201228124925.054192341@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124919.745526410@linuxfoundation.org> References: <20201228124919.745526410@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: David Woodhouse [ Upstream commit 26573a97746c7a99f394f9d398ce91a8853b3b89 ] Currently, Linux as a hypervisor guest will enable x2apic only if there are no CPUs present at boot time with an APIC ID above 255. Hotplugging a CPU later with a higher APIC ID would result in a CPU which cannot be targeted by external interrupts. Add a filter in x2apic_apic_id_valid() which can be used to prevent such CPUs from coming online, and allow x2apic to be enabled even if they are present at boot time. Fixes: ce69a784504 ("x86/apic: Enable x2APIC without interrupt remapping under KVM") Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201024213535.443185-2-dwmw2@infradead.org Signed-off-by: Sasha Levin --- arch/x86/include/asm/apic.h | 1 + arch/x86/kernel/apic/apic.c | 14 ++++++++------ arch/x86/kernel/apic/x2apic_phys.c | 9 +++++++++ 3 files changed, 18 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 3c1e51ead0722..cd2aa72e21239 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -252,6 +252,7 @@ static inline u64 native_x2apic_icr_read(void) extern int x2apic_mode; extern int x2apic_phys; +extern void __init x2apic_set_max_apicid(u32 apicid); extern void __init check_x2apic(void); extern void x2apic_setup(void); static inline int x2apic_enabled(void) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index e9456a2eef585..ab8187271d470 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1813,20 +1813,22 @@ static __init void try_to_enable_x2apic(int remap_mode) return; if (remap_mode != IRQ_REMAP_X2APIC_MODE) { - /* IR is required if there is APIC ID > 255 even when running - * under KVM + /* + * Using X2APIC without IR is not architecturally supported + * on bare metal but may be supported in guests. */ - if (max_physical_apicid > 255 || - !x86_init.hyper.x2apic_available()) { + if (!x86_init.hyper.x2apic_available()) { pr_info("x2apic: IRQ remapping doesn't support X2APIC mode\n"); x2apic_disable(); return; } /* - * without IR all CPUs can be addressed by IOAPIC/MSI - * only in physical mode + * Without IR, all CPUs can be addressed by IOAPIC/MSI only + * in physical mode, and CPUs with an APIC ID that cannnot + * be addressed must not be brought online. */ + x2apic_set_max_apicid(255); x2apic_phys = 1; } x2apic_enable(); diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c index b5cf9e7b3830c..ed56d2850e96a 100644 --- a/arch/x86/kernel/apic/x2apic_phys.c +++ b/arch/x86/kernel/apic/x2apic_phys.c @@ -13,6 +13,12 @@ int x2apic_phys; static struct apic apic_x2apic_phys; +static u32 x2apic_max_apicid __ro_after_init; + +void __init x2apic_set_max_apicid(u32 apicid) +{ + x2apic_max_apicid = apicid; +} static int __init set_x2apic_phys_mode(char *arg) { @@ -103,6 +109,9 @@ static int x2apic_phys_probe(void) /* Common x2apic functions, also used by x2apic_cluster */ int x2apic_apic_id_valid(u32 apicid) { + if (x2apic_max_apicid && apicid > x2apic_max_apicid) + return 0; + return 1; }