Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759128AbaGCRHW (ORCPT ); Thu, 3 Jul 2014 13:07:22 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:57763 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752722AbaGCRHU (ORCPT ); Thu, 3 Jul 2014 13:07:20 -0400 Date: Thu, 3 Jul 2014 19:07:11 +0200 From: Peter Zijlstra To: Andi Kleen Cc: kan.liang@intel.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH V2 2/3] perf protect LBR when Intel PT is enabled. Message-ID: <20140703170711.GW19379@twins.programming.kicks-ass.net> References: <1404324855-15166-1-git-send-email-kan.liang@intel.com> <1404324855-15166-2-git-send-email-kan.liang@intel.com> <20140703073321.GU19379@twins.programming.kicks-ass.net> <20140703155237.GQ5714@two.firstfloor.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="KAk/33nSS6LK84p9" Content-Disposition: inline In-Reply-To: <20140703155237.GQ5714@two.firstfloor.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --KAk/33nSS6LK84p9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jul 03, 2014 at 05:52:37PM +0200, Andi Kleen wrote: > > If there's active LBR users out there, we should refuse to enable PT and > > vice versa.=20 >=20 > This doesn't work, e.g. hardware debuggers can take over at any time. Tough cookies. Hardware debuggers get to deal with whatever crap they cause. --KAk/33nSS6LK84p9 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTtY2xAAoJEHZH4aRLwOS6sXcQAJpgR+9ESw2VS5K46T1KqU1g F03zUk7n6Sml80hIQ0vaizCOyi2xwqOKtIhYsdsBjVPTFR03eMSmuOZQhw1VN74r x94ICaUpU3XVtk7/i1YJSjzCNCcnN/xXr+mugdLd7qDVVkOLZcxLWAXkokEC5uS6 dxd1oEvIV41Rx2uTouMTLgNNWifR84IItBr1zhUt4YDuEPSaT/vdyTbtIwiea+oz GKDcwJFe5euKs1FyWl9A+D5E8enoxUr1+tm65Ig83Ca0WG7eX5SafvZW5uJN4EBu E3/BWukEdXODg1JvqO1QmhLAxGVel9OwrlC8ATBkmdqIaTL7ce6+0y42Bpu6f+8S Hl28YvI/CHSZ97v3A/pGjiMzDLvQbpBdJCEfw1WHfZUHzGnYXwpkASK1U6c0bavB 4j3gzbEwUQf5LjzBl1+qA5bQkEJjj/bftooiWxvmrMymwmYGk8w2Vs3lGPTkpVML wavYPRFFiYnAxRWfnWkxLcT0qeL691YnDUlmSL/TTgfUX/sCedLiPn40a6v5J/eV GGu9CvctSEdNslvsc9Dexo/INMjr5vTRkBYKa/Psmp8pObRtmshqL7sWf3u9Rk0y u/T35e8PtsujjZp2evkhgx/Qg7kIjH9/HaSV4w+PqHQDJUV2vhx9oxW0DPKU7d8L LzHiLB3D0tH4PBLlvcHp =ACfl -----END PGP SIGNATURE----- --KAk/33nSS6LK84p9-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/