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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 0750FC433E0 for ; Mon, 20 Jul 2020 09:16:05 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D076D21775 for ; Mon, 20 Jul 2020 09:16:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hSBeriNH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D076D21775 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 99711123757CD; Mon, 20 Jul 2020 02:16:04 -0700 (PDT) Received-SPF: None (mailfrom) identity=mailfrom; client-ip=2001:8b0:10b:1231::1; helo=merlin.infradead.org; envelope-from=peterz@infradead.org; receiver= Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id B4D601236F6C3 for ; Mon, 20 Jul 2020 02:16:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=LGLWvg6ZDIUlei0ZDQ3T5GmRjQgNLRaVaWwSYGqHGW4=; b=hSBeriNHtlumBJ+DPG5faJaUBK xOohGFXtfbnZk6s5lws1YyNCXqeSHDgqdGn6Wo7FyyBA8zVImTRfO722gMZD48RZoXPx+JkfpUVlu TKh11UPDMA2/enEZKUwjegXxgRSEG0uJPFvxApi4A1eN+vXlXxim2A/g4A4Ia8LiRgps7RgVk4AUi rGStWRJjZ9iLyu5d8pBo3A2cHvvBEYJbweYyDj0/J3K3u6GyAEp3FGfyjWXdvkuJD8/D+udXHtcZh qpbn6ZAr/RTIgKpXTPWMwjJeHwjDlkVR6Uv9xhWno3N5yy+Bdjf6QTUGXzF98MYmW1Egoo81znxWW dnOw8mjQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jxRtr-0005wP-Ts; Mon, 20 Jul 2020 09:15:56 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 89F023010C8; Mon, 20 Jul 2020 11:15:54 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7B365205A7673; Mon, 20 Jul 2020 11:15:54 +0200 (CEST) Date: Mon, 20 Jul 2020 11:15:54 +0200 From: Peter Zijlstra To: Ira Weiny Subject: Re: [PATCH RFC V2 04/17] x86/pks: Preserve the PKRS MSR on context switch Message-ID: <20200720091554.GN10769@hirez.programming.kicks-ass.net> References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-5-ira.weiny@intel.com> <20200717085954.GY10769@hirez.programming.kicks-ass.net> <20200717223407.GS3008823@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200717223407.GS3008823@iweiny-DESK2.sc.intel.com> Message-ID-Hash: L4BRNA5PPUTETPJ2O6ZWSVLZAIJ4E5FR X-Message-ID-Hash: L4BRNA5PPUTETPJ2O6ZWSVLZAIJ4E5FR X-MailFrom: peterz@infradead.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Fenghua Yu , x86@kernel.org, Dave Hansen , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Jul 17, 2020 at 03:34:07PM -0700, Ira Weiny wrote: > On Fri, Jul 17, 2020 at 10:59:54AM +0200, Peter Zijlstra wrote: > > On Fri, Jul 17, 2020 at 12:20:43AM -0700, ira.weiny@intel.com wrote: > > > +/* > > > + * Write the PKey Register Supervisor. This must be run with preemption > > > + * disabled as it does not guarantee the atomicity of updating the pkrs_cache > > > + * and MSR on its own. > > > + */ > > > +void write_pkrs(u32 pkrs_val) > > > +{ > > > + this_cpu_write(pkrs_cache, pkrs_val); > > > + wrmsrl(MSR_IA32_PKRS, pkrs_val); > > > +} > > > > Should we write that like: > > > > void write_pkrs(u32 pkr) > > { > > u32 *pkrs = get_cpu_ptr(pkrs_cache); > > if (*pkrs != pkr) { > > *pkrs = pkr; > > wrmsrl(MSR_IA32_PKRS, pkr); > > } > > put_cpu_ptrpkrs_cache); > > } > > > > given that we fundamentally need to serialize againt schedule() here. > > Yes. That seems better. > > That also means pks_sched_in() can be simplified to just > > static inline void pks_sched_in(void) > { > write_pkrs(current->thread.saved_pkrs); > } > > Because of the built WRMSR avoidance. > > However, pkrs_cache is static so I think I need to use {get,put}_cpu_var() here > don't I? Or get_cpu_ptr(&pkrs_cache), sorry for the typo :-) _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org