Re: [Xen-devel] [patch] pae: tlbflush linear page table updates

[Gerd Knorr <kraxel@xxxxxxx>]

On Wed, Aug 10, 2005 at 11:54:22AM +0100, Keir Fraser wrote:
> 
> On 10 Aug 2005, at 11:28, Gerd Knorr wrote:
> 
> >And it isn't the mod_l3 update which broke PAE, it's the
> >__not_mapped() removal.  Applying the bits below reversed
> >makes PAE boot again.
> 
> afaics the only change for pae is use of __get_user() rather than 
> directly reading from the pl2e. Perhaps __get_user() on 8-byte 
> quantities is broken, although I'm sure that must be used elsewhere and 
> so is tested....

Sure?  The patch below fixes it for me.

The tlbflush stuff is red herring btw, the real difference is
optimization.  Build with "optimize=n" boot fine, others don't.

  Gerd

Index: xen/arch/x86/mm.c
===================================================================
--- xen.orig/arch/x86/mm.c      2005-08-10 14:09:59.476430318 +0200
+++ xen/arch/x86/mm.c   2005-08-10 14:13:50.906986616 +0200
@@ -2940,7 +2940,7 @@ int ptwr_do_page_fault(struct domain *d,
     pl2e = &__linear_l2_table[l2_idx];
     which = PTWR_PT_INACTIVE;
 
-    if ( (__get_user(l2e.l2, &pl2e->l2) == 0) && (l2e_get_pfn(l2e) == pfn) )
+    if ( (__copy_from_user(&l2e, pl2e, sizeof(l2e)) == 0) && (l2e_get_pfn(l2e) 
== pfn) )
     {
         /*
          * Check the PRESENT bit to set ACTIVE mode.

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