From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932142AbZHMTr5 (ORCPT ); Thu, 13 Aug 2009 15:47:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932099AbZHMTr4 (ORCPT ); Thu, 13 Aug 2009 15:47:56 -0400 Received: from kroah.org ([198.145.64.141]:36746 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932098AbZHMTrx (ORCPT ); Thu, 13 Aug 2009 15:47:53 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Thu Aug 13 12:43:37 2009 Message-Id: <20090813194337.619553936@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Thu, 13 Aug 2009 12:40:35 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mark Langsdorf , Joerg Roedel , jbarnes@virtuousgeek.org, Ingo Molnar Subject: [patch 14/28] x86: enable GART-IOMMU only after setting up protection methods References: <20090813194021.446758568@mini.kroah.org> Content-Disposition: inline; filename=x86-enable-gart-iommu-only-after-setting-up-protection-methods.patch In-Reply-To: <20090813194554.GA13947@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mark Langsdorf commit fe2245c905631a3a353504fc04388ce3dfaf9d9e upstream. The current code to set up the GART as an IOMMU enables GART translations before it removes the aperture from the kernel memory map, sets the GART PTEs to UC, sets up the guard and scratch pages, or does a wbinvd(). This leaves the possibility of cache aliasing open and can cause system crashes. Re-order the code so as to enable the GART translations only after all safeguards are in place and the tlb has been flushed. AMD has tested this patch on both Istanbul systems and 1st generation Opteron systems with APG enabled and seen no adverse effects. Istanbul systems with HT Assist enabled sometimes see MCE errors due to cache artifacts with the unmodified code. Signed-off-by: Mark Langsdorf Cc: Joerg Roedel Cc: akpm@linux-foundation.org Cc: jbarnes@virtuousgeek.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/pci-gart_64.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/pci-gart_64.c +++ b/arch/x86/kernel/pci-gart_64.c @@ -658,8 +658,6 @@ static __init int init_k8_gatt(struct ag memset(gatt, 0, gatt_size); agp_gatt_table = gatt; - enable_gart_translations(); - error = sysdev_class_register(&gart_sysdev_class); if (!error) error = sysdev_register(&device_gart); @@ -828,6 +826,14 @@ void __init gart_iommu_init(void) wbinvd(); /* + * Now all caches are flushed and we can safely enable + * GART hardware. Doing it early leaves the possibility + * of stale cache entries that can lead to GART PTE + * errors. + */ + enable_gart_translations(); + + /* * Try to workaround a bug (thanks to BenH): * Set unmapped entries to a scratch page instead of 0. * Any prefetches that hit unmapped entries won't get an bus abort