From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x224yOAkpF4+YhrzgRhN1c8LRpb+oYRXUrZzF/79v2ZYT/Z0DsMgg6+8fTihjExdpEhGsBara ARC-Seal: i=1; a=rsa-sha256; t=1518210558; cv=none; d=google.com; s=arc-20160816; b=O8Tm2TuKUSgH0yH9S28f6nvmEg9gCGEG3YWWtR4bs14gk8xFwbrXpwxWStviR254MO 1aOiwjJX1//dTGtUDatRrOtI0ZmqtXH/zoxTVHz1O6IMuzOsqDFe+8iv4Dw6iRvI2UV0 8GcnQA/MlBoKwLQZhs/mS+SBTytVmyrze5SYFgDxSNMAqSRX9IfcARi4jpV5PBUZLTHO OziSC4zgE7iJ2WGoLdI1s1SPDVZKdX3b4OJLpyOCc/tR4gDoiEJv3JpEpZ+rtE8qBMNB UY3EFiqR1rjkX9mh5KAcJ3Sfzjs88Plfji1CW2JV9nz/JV3Hs0/qaM8BjCw7HahnorWt 9tpQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:arc-authentication-results; bh=VkfdadkEGZs3WnISVAlFGkfnSB24HdgcHUlJm4PIOts=; b=tsG9XlZjtlhrK0xvdYoYpPBTi+IpeWPypXR9FO8plTlDel8QcWANj4eHRHu1ww+g60 LrbIuu3NU9GfUD8ALMHHE9wIE1wAyKRr3Ji6+BWFQAqngCIkY2n6cezhMS+i51SxVoPV kIpEm3cpIslFMFcsN/CGfkyfA4b2lPpdWJPYVGIY169QGNmIhpUpeJv/LZf+3kWOOGGb OzeqRJgcxaP3Yn1MXuQp7sb7xmI0i4aZ5UQwGK4AoaIJl6WsWegJQwi6JX/VQ9PD4Wlu 5zSES5rIPUHmkf+jrVQiCIp1fXqEt/g4FXEnugir0mh30MT6EEjm/4WR3V58QfJ3TeB0 HvDQ== ARC-Authentication-Results: i=1; mx.google.com; spf=neutral (google.com: 195.113.26.193 is neither permitted nor denied by best guess record for domain of pavel@ucw.cz) smtp.mailfrom=pavel@ucw.cz Authentication-Results: mx.google.com; spf=neutral (google.com: 195.113.26.193 is neither permitted nor denied by best guess record for domain of pavel@ucw.cz) smtp.mailfrom=pavel@ucw.cz Date: Fri, 9 Feb 2018 22:09:18 +0100 From: Pavel Machek 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 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: User-Agent: Mutt/1.5.23 (2014-03-12) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591914900490843452?= X-GMAIL-MSGID: =?utf-8?q?1591959154814868003?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --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+--