From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763538AbZEHATq (ORCPT ); Thu, 7 May 2009 20:19:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758904AbZEHAKW (ORCPT ); Thu, 7 May 2009 20:10:22 -0400 Received: from adsl-76-233-236-102.dsl.pltn13.sbcglobal.net ([76.233.236.102]:52721 "EHLO abulafia.goop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755272AbZEHAJ6 (ORCPT ); Thu, 7 May 2009 20:09:58 -0400 From: Jeremy Fitzhardinge To: Ingo Molnar Cc: the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel , Jeremy Fitzhardinge Subject: [PATCH 5/8] xen/i386: make sure initial VGA/ISA mappings are not overridden Date: Thu, 7 May 2009 13:24:59 -0700 Message-Id: <1241727902-3176-6-git-send-email-jeremy@goop.org> X-Mailer: git-send-email 1.6.0.6 In-Reply-To: <1241727902-3176-1-git-send-email-jeremy@goop.org> References: <1241727902-3176-1-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. This makes 32-bit dom0 VGA work properly. Thanks to Gerd Hoffman for pointing this out. 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 a96f5b9..5af62d8 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1443,10 +1443,17 @@ 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