From nobody Mon Apr 6 09:41:24 2026 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 B0148C38145 for ; Thu, 8 Sep 2022 19:57:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229810AbiIHT5b (ORCPT ); Thu, 8 Sep 2022 15:57:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229451AbiIHT5W (ORCPT ); Thu, 8 Sep 2022 15:57:22 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 288E4FDBA4 for ; Thu, 8 Sep 2022 12:57:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662667040; 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: references:references; bh=K3kPDvRnZ5sJSBggdbe1FgXRWBmDeuCU2G3Z/g5bs1o=; b=Ls0xReApBHVSoTHb4yJhCxtj7UitCuWbho/V5XksyuOXKwBW83Zq6DTTzT4BNoWp7WtXt3 iylqggFYfLo3vmN04hBBVilBsBXTRFFLA3vGRq13JEU2EcHFuAPbgCYLfN0kaClkvO72GW 8wKX8AlrqMhfXNhei1I6Zzr2aPIdj8M= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-207-L21TuuGmPeWsliL34oBB_g-1; Thu, 08 Sep 2022 15:57:19 -0400 X-MC-Unique: L21TuuGmPeWsliL34oBB_g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8E9A218A6522; Thu, 8 Sep 2022 19:57:18 +0000 (UTC) Received: from fuller.cnet (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E4201121315; Thu, 8 Sep 2022 19:57:18 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 292F84148B8E; Thu, 8 Sep 2022 16:54:07 -0300 (-03) Message-ID: <20220908195111.966739489@redhat.com> User-Agent: quilt/0.66 Date: Thu, 08 Sep 2022 16:29:06 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Frederic Weisbecker , Juri Lelli , Daniel Bristot de Oliveira , Prasad Pandit , Valentin Schneider , Yair Podemsky , Thomas Gleixner , Marcelo Tosatti Subject: [RFC PATCH 7/7] mtrr_add_page/mtrr_del_page: check for block interference CPUs References: <20220908192859.546633738@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Check if any online CPU in the system is tagged as a block interference CPU, and if so return an error to mtrr_add_page/mtrr_del_page.=20 This can avoid interference to such CPUs (while allowing userspace to handle the failures). Signed-off-by: Marcelo Tosatti Index: linux-2.6/arch/x86/kernel/cpu/mtrr/mtrr.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-2.6.orig/arch/x86/kernel/cpu/mtrr/mtrr.c +++ linux-2.6/arch/x86/kernel/cpu/mtrr/mtrr.c @@ -45,6 +45,7 @@ #include #include #include +#include =20 #include #include @@ -335,6 +336,13 @@ int mtrr_add_page(unsigned long base, un error =3D -EINVAL; replace =3D -1; =20 + block_interf_read_lock(); + + if (cpumask_intersects(block_interf_cpumask, cpu_online_mask)) { + block_interf_read_unlock(); + return -EPERM; + } + /* No CPU hotplug when we change MTRR entries */ cpus_read_lock(); =20 @@ -399,6 +407,7 @@ int mtrr_add_page(unsigned long base, un out: mutex_unlock(&mtrr_mutex); cpus_read_unlock(); + block_interf_read_unlock(); return error; } =20 @@ -484,6 +493,11 @@ int mtrr_del_page(int reg, unsigned long return -ENODEV; =20 max =3D num_var_ranges; + block_interf_read_lock(); + if (cpumask_intersects(block_interf_cpumask, cpu_online_mask)) { + block_interf_read_unlock(); + return -EPERM; + } /* No CPU hotplug when we change MTRR entries */ cpus_read_lock(); mutex_lock(&mtrr_mutex); @@ -521,6 +535,7 @@ int mtrr_del_page(int reg, unsigned long out: mutex_unlock(&mtrr_mutex); cpus_read_unlock(); + block_interf_read_unlock(); return error; }