[PATCH] x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

[PATCH] x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

[Jan Beulich]

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While putting together the workaround announced in
http://lists.xen.org/archives/html/xen-devel/2012-06/msg00709.html, I
found that mod_l1_entry(), upon encountering a set bit in
mmio_ro_ranges, would return 1 instead of 0 (the removal of the write
permission is supposed to be entirely transparent to the caller, even
more so to the calling guest).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -1875,6 +1875,7 @@ static int mod_l1_entry(l1_pgentry_t *pl
             break;
         case 1:
             l1e_remove_flags(nl1e, _PAGE_RW);
+            rc = 0;
             break;
         }
         if ( page )




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x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

While putting together the workaround announced in
http://lists.xen.org/archives/html/xen-devel/2012-06/msg00709.html, I
found that mod_l1_entry(), upon encountering a set bit in
mmio_ro_ranges, would return 1 instead of 0 (the removal of the write
permission is supposed to be entirely transparent to the caller, even
more so to the calling guest).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -1875,6 +1875,7 @@ static int mod_l1_entry(l1_pgentry_t *pl
             break;
         case 1:
             l1e_remove_flags(nl1e, _PAGE_RW);
+            rc = 0;
             break;
         }
         if ( page )

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Re: [PATCH] x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

[Keir Fraser]

On 20/06/2012 16:18, "Jan Beulich" <JBeulich@suse.com> wrote:

> While putting together the workaround announced in
> http://lists.xen.org/archives/html/xen-devel/2012-06/msg00709.html, I
> found that mod_l1_entry(), upon encountering a set bit in
> mmio_ro_ranges, would return 1 instead of 0 (the removal of the write
> permission is supposed to be entirely transparent to the caller, even
> more so to the calling guest).
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Keir Fraser <keir@xen.org>

> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -1875,6 +1875,7 @@ static int mod_l1_entry(l1_pgentry_t *pl
>              break;
>          case 1:
>              l1e_remove_flags(nl1e, _PAGE_RW);
> +            rc = 0;
>              break;
>          }
>          if ( page )
> 
> 
> 
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> Xen-devel@lists.xen.org
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