WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [PATCH 16/16] xen/i386: make sure initial VGA/ISA mappings a

To: Ingo Molnar <mingo@xxxxxxx>
Subject: [Xen-devel] [PATCH 16/16] xen/i386: make sure initial VGA/ISA mappings are not overridden
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Wed, 27 May 2009 00:15:38 -0700
Cc: Chris Wright <chrisw@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ky Srinivasan <ksrinivasan@xxxxxxxxxx>, kurt.hackel@xxxxxxxxxx, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, Jens Axboe <jens.axboe@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Greg KH <gregkh@xxxxxxx>
Delivery-date: Wed, 27 May 2009 00:29:17 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1243408538-21100-1-git-send-email-jeremy@xxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1243408538-21100-1-git-send-email-jeremy@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

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 <kraxel@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 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


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel