From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 4AD7E6B026F for ; Fri, 9 Feb 2018 16:09:19 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id t14so4402888wmc.5 for ; Fri, 09 Feb 2018 13:09:19 -0800 (PST) Received: from atrey.karlin.mff.cuni.cz (atrey.karlin.mff.cuni.cz. [195.113.26.193]) by mx.google.com with ESMTPS id l6si2320284wrb.94.2018.02.09.13.09.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Feb 2018 13:09:18 -0800 (PST) Date: Fri, 9 Feb 2018 22:09:18 +0100 From: Pavel Machek Subject: Re: [PATCH 00/31 v2] PTI support for x86_32 Message-ID: <20180209210918.GA7333@amd> References: <1518168340-9392-1-git-send-email-joro@8bytes.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="8t9RHnE3ZwKMSgU+" Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Joerg Roedel , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , X86 ML , LKML , Linux-MM , Linus Torvalds , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , "Liguori, Anthony" , Daniel Gruss , Hugh Dickins , Kees Cook , Andrea Arcangeli , Waiman Long , Joerg Roedel --8t9RHnE3ZwKMSgU+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri 2018-02-09 17:47:43, Andy Lutomirski wrote: > On Fri, Feb 9, 2018 at 9:25 AM, Joerg Roedel wrote: > > Hi, > > > > here is the second version of my PTI implementation for > > x86_32, based on tip/x86-pti-for-linus. It took a lot longer > > than I had hoped, but there have been a number of obstacles > > on the way. It also isn't the small patch-set anymore that v1 > > was, but compared to it this one actually works :) >=20 > One thing worth noting is that performance of this whole series is > going to be abysmal due to the complete lack of 32-bit PCID. Maybe > any kernel built with this option set that runs on a CPU that has >the What kind of slowdown are we talking about here? > PCID bit set in CPUID should print a big fat warning like "WARNING: > you are using 32-bit PTI on a 64-bit PCID-capable CPU. Your > performance will increase dramatically if you switch to a 64-bit > kernel." Hardware supports PCID even on 32-bit kernels, no? Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --8t9RHnE3ZwKMSgU+ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlp+Df0ACgkQMOfwapXb+vLUOQCgsuGLg/bps5hW4emf9c2c6MEJ DcAAn1C0vweSUfM1H+KV6WqM9hqO0T5s =CfYt -----END PGP SIGNATURE----- --8t9RHnE3ZwKMSgU+-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org