Re: [Xen-ia64-devel] [PATCH] translate_domain_pte must handle ED bit

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Mon, Feb 20, 2006 at 10:54:41PM +0800, Tian, Kevin wrote:
> >From: Isaku Yamahata
> >Sent: 2006年2月20日 16:32
> >
> >translate_domain_pte() must handle ED bit explicitly.
> >This case can occur because of vcpu_itc_d().
> >
> >--
> >Yamahata
> 
> Seems a bug, however do you know why it only jumps out now? Seems PAGE_ED is 
> likely on in lookup_domain_mpa...

Perhaps vcpu->arch.dtlb cache hit in vcpu_translate() is very rare
because of tlb cache and VHPT. 
To hit this bug it would be necessary to run a huge amount of
guest domains competing tlb cache and VHPT entries.
It seems that no one does.

Otherwise artificial repeated vhpt/tlb flush in xen for debug might have
this bug appear.


> BTW, bit[53-63] are ignored bits per 4.1.1.5 of SDM2, and then you can just 
> ignore them instead of BUG there. ;-)

Hmm, the current code seems to assume just simply that bit[53-63] and
ED bit[52] can be used for address machine page frame number.
Some clean up might be needed.

-- 
yamahata

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