From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761837AbZE0HW0 (ORCPT ); Wed, 27 May 2009 03:22:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760852AbZE0HRt (ORCPT ); Wed, 27 May 2009 03:17:49 -0400 Received: from claw.goop.org ([74.207.240.146]:41512 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760836AbZE0HRs (ORCPT ); Wed, 27 May 2009 03:17:48 -0400 From: Jeremy Fitzhardinge To: Ingo Molnar Cc: the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel , Greg KH , Jens Axboe , Chris Wright , kurt.hackel@oracle.com, Andrew Morton , Ky Srinivasan , Beulich , Linus Torvalds , Jeremy Fitzhardinge Subject: [PATCH 16/16] xen/i386: make sure initial VGA/ISA mappings are not overridden Date: Wed, 27 May 2009 00:15:38 -0700 Message-Id: <1243408538-21100-17-git-send-email-jeremy@goop.org> X-Mailer: git-send-email 1.6.0.6 In-Reply-To: <1243408538-21100-1-git-send-email-jeremy@goop.org> References: <1243408538-21100-1-git-send-email-jeremy@goop.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeremy Fitzhardinge arch/x86/mm/init_32.c overrides the ISA/VGA mappings with direct mappings which do not have _PAGE_IOMAP set, thereby making the ISA space inaccessible. This patch adds to the existing hack to make sure the pre-constructed ISA mappings are not incorrectly overwritten. Thanks to Gerd Hoffman for pointing this out. [ Impact: Makes 32-bit dom0 VGA work properly. ] Diagnosed-by: Gerd Hoffmann Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/mmu.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 85d9d18..331e52d 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1502,10 +1502,17 @@ static void *xen_kmap_atomic_pte(struct page *page, enum km_type type) #ifdef CONFIG_X86_32 static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte) { - /* If there's an existing pte, then don't allow _PAGE_RW to be set */ - if (pte_val_ma(*ptep) & _PAGE_PRESENT) + pte_t oldpte = *ptep; + + if (pte_flags(oldpte) & _PAGE_PRESENT) { + /* Don't allow existing IO mappings to be overridden */ + if (pte_flags(oldpte) & _PAGE_IOMAP) + pte = oldpte; + + /* Don't allow _PAGE_RW to be set on existing pte */ pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) & pte_val_ma(pte)); + } return pte; } -- 1.6.0.6