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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 0417AC47087 for ; Fri, 28 May 2021 17:19:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8F89C613B5 for ; Fri, 28 May 2021 17:19:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F89C613B5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 89C886B0075; Fri, 28 May 2021 13:19:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 84BCF6B0078; Fri, 28 May 2021 13:19:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 712F56B007B; Fri, 28 May 2021 13:19:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0238.hostedemail.com [216.40.44.238]) by kanga.kvack.org (Postfix) with ESMTP id 41CBD6B0075 for ; Fri, 28 May 2021 13:19:04 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id BE381181AEF21 for ; Fri, 28 May 2021 17:19:03 +0000 (UTC) X-FDA: 78191300166.14.691A34A Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf08.hostedemail.com (Postfix) with ESMTP id 9597F8019EA1 for ; Fri, 28 May 2021 17:18:54 +0000 (UTC) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1622222341; 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: in-reply-to:in-reply-to:references:references; bh=7XXMkpQsbehg+qNK7ZVP15wb2+6lgaNxZ16dFAzSN/o=; b=EuPc6Lj5b9dnblHQPS+OwPpQ7zcB8NAYy/kfsmS7bO4+Hx0QEUEPE864ApUB8ZRLpnr+dV hUiPgLtRO3dOJKQuh/64xShuq74ZQCjsfxSyBvZWar2Z2KifbCPmhR3eSTxXCe51oAYL0U 0PvaD/UXFh+vnsiMwS8r/ervoWmCCbS9HjbphDKPzhAQOfrMd2FSCXYqGKqvJgo5IfKd3Y 00zLxNodFIcWXF7yN2rBZg/84RXs061KXOQsc5fiLFs+9YfPlGI14CATq4IlTY7AfUnJIM uBeSV0DB+ydUr8WoXo7eVeC0MgREjx3vWAHq1X0W5lHkf2GUt2dVYrSCB2kx1w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1622222341; 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: in-reply-to:in-reply-to:references:references; bh=7XXMkpQsbehg+qNK7ZVP15wb2+6lgaNxZ16dFAzSN/o=; b=gUaXmYnowiug3bVJ1B45870TyHL7gfy7S310FEOStjQTVAwFwRfASjTeLpewx7IkJ6VHkq 6C60yQ4MUIupmQCw== To: Dave Hansen , Dave Hansen , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de, x86@kernel.org, luto@kernel.org, shuah@kernel.org, babu.moger@amd.com, dave.kleikamp@oracle.com, linuxram@us.ibm.com, bauerman@linux.ibm.com Subject: Re: [PATCH 0/5] x86/pkeys: PKRU manipulation bug fixes and cleanups In-Reply-To: <4c3bfc27-a542-8e91-7ccf-4be8b1e6c844@intel.com> References: <20210527235109.B2A9F45F@viggo.jf.intel.com> <87eedq7u2b.ffs@nanos.tec.linutronix.de> <4c3bfc27-a542-8e91-7ccf-4be8b1e6c844@intel.com> Date: Fri, 28 May 2021 19:19:00 +0200 Message-ID: <878s3y7p4r.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 9597F8019EA1 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=EuPc6Lj5; dkim=pass header.d=linutronix.de header.s=2020e header.b=gUaXmYno; spf=pass (imf08.hostedemail.com: domain of tglx@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=tglx@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de X-Rspamd-Server: rspam04 X-Stat-Signature: js7kcfgdczmbdbrui51dhbi8g4x9gkrx X-HE-Tag: 1622222334-52335 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 28 2021 at 09:11, Dave Hansen wrote: > On 5/28/21 8:32 AM, Thomas Gleixner wrote: > There are also the usual concerns that folks doing user-level context > switching or other insanity get PKRU context switching for "free" when > it's XSAVE-managed. Moving away from that could break them. Both issues are trivial to solve. We can have pkru enabled in xcr0 and just do not restore it when returning to user space (clear the mask bit). When we restore it in sigrestore via xrstor then we read it via rdpkru afterwards and update task->thread.pkru. Thanks, tglx