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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 80C13C433DF for ; Thu, 15 Oct 2020 03:46:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EEF622245 for ; Thu, 15 Oct 2020 03:46:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730320AbgJODqq (ORCPT ); Wed, 14 Oct 2020 23:46:46 -0400 Received: from mga03.intel.com ([134.134.136.65]:19759 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727281AbgJODqq (ORCPT ); Wed, 14 Oct 2020 23:46:46 -0400 IronPort-SDR: oqXXNKu6P/DWlqnbFJQN/3W5BEe+cUTAQc62mFUJ4eOu11uxTB1rGIl7Nz3Skg62oOoQYh9E4R hSPkgNwu9Mhg== X-IronPort-AV: E=McAfee;i="6000,8403,9774"; a="166313689" X-IronPort-AV: E=Sophos;i="5.77,377,1596524400"; d="scan'208";a="166313689" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2020 20:46:45 -0700 IronPort-SDR: frVKPMJAzb1m9jivZ/XfXNx7VCqDkNNADy0hOKKQpIfrYnJ8mOjxbWGy/FPBq9IrrLYbuNMuZF XeLLSEBZdFVw== X-IronPort-AV: E=Sophos;i="5.77,377,1596524400"; d="scan'208";a="531094057" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2020 20:46:45 -0700 Date: Wed, 14 Oct 2020 20:46:45 -0700 From: Ira Weiny To: Dave Hansen Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Peter Zijlstra , Dave Hansen , x86@kernel.org, Dan Williams , Andrew Morton , Fenghua Yu , 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 Subject: Re: [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions Message-ID: <20201015034645.GQ2046448@iweiny-DESK2.sc.intel.com> References: <20201009194258.3207172-1-ira.weiny@intel.com> <20201009194258.3207172-8-ira.weiny@intel.com> <6006a4c8-32bd-04ca-95cc-b2736a5cef72@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6006a4c8-32bd-04ca-95cc-b2736a5cef72@intel.com> User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Tue, Oct 13, 2020 at 11:52:32AM -0700, Dave Hansen wrote: > On 10/9/20 12:42 PM, ira.weiny@intel.com wrote: > > @@ -341,6 +341,9 @@ noinstr void irqentry_enter(struct pt_regs *regs, irqentry_state_t *state) > > /* Use the combo lockdep/tracing function */ > > trace_hardirqs_off(); > > instrumentation_end(); > > + > > +done: > > + irq_save_pkrs(state); > > } > > One nit: This saves *and* sets PKRS. It's not obvious from the call > here that PKRS is altered at this site. Seems like there could be a > better name. > > Even if we did: > > irq_save_set_pkrs(state, INIT_VAL); > > It would probably compile down to the same thing, but be *really* > obvious what's going on. I suppose that is true. But I think it is odd having a parameter which is the same for every call site. But I'm not going to quibble over something like this. Changed, Ira > > > void irqentry_exit_cond_resched(void) > > @@ -362,7 +365,12 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t *state) > > /* Check whether this returns to user mode */ > > if (user_mode(regs)) { > > irqentry_exit_to_user_mode(regs); > > - } else if (!regs_irqs_disabled(regs)) { > > + return; > > + } > > + > > + irq_restore_pkrs(state); > > + > > + if (!regs_irqs_disabled(regs)) { > > /* > > * If RCU was not watching on entry this needs to be done > > * carefully and needs the same ordering of lockdep/tracing > > >