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 3E232C43457 for ; Thu, 15 Oct 2020 03:46:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CDECA22254 for ; Thu, 15 Oct 2020 03:46:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDECA22254 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 247466B0062; Wed, 14 Oct 2020 23:46:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F8626B0068; Wed, 14 Oct 2020 23:46:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C0C56B006E; Wed, 14 Oct 2020 23:46:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0023.hostedemail.com [216.40.44.23]) by kanga.kvack.org (Postfix) with ESMTP id D21336B0062 for ; Wed, 14 Oct 2020 23:46:48 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 6E7D13625 for ; Thu, 15 Oct 2020 03:46:48 +0000 (UTC) X-FDA: 77372773296.25.frog84_000409427211 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 4AE861804E3A0 for ; Thu, 15 Oct 2020 03:46:48 +0000 (UTC) X-HE-Tag: frog84_000409427211 X-Filterd-Recvd-Size: 3676 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Thu, 15 Oct 2020 03:46:47 +0000 (UTC) IronPort-SDR: f/BKalg0sBg3sInoO3r/8lU+9vG5N1Xw+58a/TIsVFnuh/DL8lDUlNSf33JRuWb/e5Ii+cmj3i 1mC5TlVMlcJw== X-IronPort-AV: E=McAfee;i="6000,8403,9774"; a="162787038" X-IronPort-AV: E=Sophos;i="5.77,377,1596524400"; d="scan'208";a="162787038" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga102.fm.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) 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 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 > > >