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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4155C433F5 for ; Wed, 2 Mar 2022 13:49:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242348AbiCBNuT (ORCPT ); Wed, 2 Mar 2022 08:50:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235666AbiCBNuR (ORCPT ); Wed, 2 Mar 2022 08:50:17 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FE193BF9E for ; Wed, 2 Mar 2022 05:49:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=EFiW5epXAvMj3+Y4RhnOy43XObQbRYk+KnNyIX9yPps=; b=ZKYRDQpNY7oifdr6jJAlqDAVIa z8Cl5Wpt6WrMAj3zRivui5pjc0f2lnaJG1iCcmMeO2kuZMHITh/DJJcfPYDZQcwpLCeW45XR+NEjZ ZsGdW/gY6tXE3hXjSJAojECEpnMs1cTh2y6838hvjPKmq0PTgdR6td1GJ7Lr3kwapg6U01aLKfcke 8kRdaQjH9I5XBDWQsZpNAQz51+30rzS0xFwfF6dkrxpTE6+XSizZ00upUqqsDG5hxVbsWTVDvrG7L ncler03mZZEGOjAlZ9Gm0M5pqFLnk0VMJhcRIL1tsd/qL/A5fgFTfhPwYqHsnf6VV0A2JFwgfMAAb 2JIxOgBw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPPLp-00AeJG-3i; Wed, 02 Mar 2022 13:49:09 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5BA6530021B; Wed, 2 Mar 2022 14:49:08 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3F5DC32201D61; Wed, 2 Mar 2022 14:49:08 +0100 (CET) Date: Wed, 2 Mar 2022 14:49:08 +0100 From: Peter Zijlstra To: "Edgecombe, Rick P" Cc: "keescook@chromium.org" , "Poimboe, Josh" , "linux-kernel@vger.kernel.org" , "Cooper, Andrew" , "hjl.tools@gmail.com" , "rostedt@goodmis.org" , "joao@overdrivepizza.com" , "samitolvanen@google.com" , "x86@kernel.org" , "mark.rutland@arm.com" , "alexei.starovoitov@gmail.com" , "Milburn, Alyssa" , "mhiramat@kernel.org" , "mbenes@suse.cz" , "ndesaulniers@google.com" Subject: Re: [PATCH v2 18/39] x86/ibt: Add IBT feature, MSR and #CP handling Message-ID: References: <20220224145138.952963315@infradead.org> <20220224151323.069205370@infradead.org> <20220301210245.GM11184@worktop.programming.kicks-ass.net> <20220301231303.pqexbxkpte6yjiww@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 02, 2022 at 01:59:46AM +0000, Edgecombe, Rick P wrote: > As for pinning strength, I'm not understanding this kexec asm enough to > say for sure how much better it is than just removing the bit from the > pinning mask. I think some future hardening around preventing turning > off IBT might still be worthwhile. > > Kees, I think you brought up the pinning, what do you think of this? IIRC the whole purpose of that was to ensure that the cr4_update_irqsoff() function itself isn't a useful gadget to manipulate CR4 with.