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Re: [Xen-devel] [PATCH for-4.6] libxl: move calling libxl__arch_domain_construct_memmap to right place

On Wed, Aug 05, 2015 at 11:48:55AM +0100, Ian Campbell wrote:
> On Wed, 2015-08-05 at 11:43 +0100, Wei Liu wrote:
> > On Wed, Aug 05, 2015 at 11:38:54AM +0100, Ian Campbell wrote:
> > > On Wed, 2015-08-05 at 11:23 +0100, Wei Liu wrote:
> > > > This function was called in the wrong place, because both
> > > > libxl__vnuma_build_vmemrange_hvm and xc_hvm_build rely on its output.
> > > 
> > > What is the effect of this call being in the wrong place? Presumably 
> > > one or
> > > the other of those functions reaches the wrong conclusion?
> > 
> > Originally, by the time that function got called, all guest pages were
> > already populated.  The end result is E820 map disagrees with what vNUMA
> > says and what address ranges memory actually resides, i.e. risk of guest
> > accessing region that doesn't have backing pages.
> Ouch. This should certainly be explained in the commit message.
> With that: Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

I will post v2 shortly with that information in commit message.

> Although perhaps we should wait for confirmation this fix doesn't regress
> RMRR somehow?

I doubt it will. The code as-is is already broken for RMRR. But let's
wait till tomorrow for Tiejun to reply.

If he doesn't reply by tomorrow, I suggest we apply v2 first and
fix up any subsequent issues later.


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