Re: [Xen-devel] [PATCH 05/10] VMX: add help functions to support PML

[Tim Deegan <tim@xxxxxxx>]

At 15:05 +0800 on 10 Apr (1428678346), Kai Huang wrote:
> 
> 
> On 04/09/2015 08:00 PM, Tim Deegan wrote:
> > Hi,
> >
> > That's also buggy, because there's no locking here to make sure
> > gfn->mfn->gfn ends up in the right place. :(
> Yes you are right. Thanks for pointing out.
> 
> Just curious, looks if I use get_gfn_type_access and put_gfn here, the 
> gfn->mfn->gfn can be guaranteed, and it's safe to use them here, right?

Yes, that would be the right way to do it.

In this particular case, there's another race too: the gfn might have
been entirely deleted after it's logged by PML but before the entry is
processed here.  I don't think that's a problem here, because if the
gfn's not mapped any more it's not relevant that it's dirty.  Just
mentioning it out of interest.

Cheers,

Tim.

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