Re: [Xen-devel] [PATCH] [Xen] Check FADT's signature

[Stefan Berger <stefanb@xxxxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 08/10/2007
11:58:21 AM:

> So the bug could be either that the read is getting hoisted above
> the pagetable update (unlikely) or that there is a stale TLB entry
> (more likely). You could discount the first possibility by replacing
> your local_flush_tlb_pge() with mb() at the end of 
> map_pages_to_xen(). If that does not fix the bug then the problem
is
> not that the read is getting hoisted.
> 
> The TLB handling looks correct though — if the modified PTE was not
> previously empty then we execute an INVLPG on that virtual address.
> Might be worth adding some tracing around there to see if the code
> thinks the PTE was previously present, and hence whether the INVLPG
> actually gets executed?

local_flush_tlb_one() does NOT get executed the first
time, but upon the second attempt.
The mb() alone did NOT help.

  Stefan

> 
>  -- Keir
> 
> On 10/8/07 16:35, "Stefan Berger" <stefanb@xxxxxxxxxx>
wrote:

> Keir Fraser <keir@xxxxxxxxxxxxx> wrote
on 08/10/2007 11:09:43 AM:
> 
> > Not by my reading of the code, but your testing shows differently
;-)
> > 
> > Have you tried adding tracing to map_pages_to_xen()? That’s
the guts
> > of the remapping code. 
> 
> Now I did... 
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