From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ed White <edmund.h.white@intel.com>
Subject: Re: [PATCH v2 09/12] x86/altp2m: add remaining support
	routines.
Date: Thu, 25 Jun 2015 09:31:20 -0700
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To: "Lengyel, Tamas" <tlengyel@novetta.com>
Cc: Ravi Sahita <ravi.sahita@intel.com>, Wei Liu <wei.liu2@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>, Xen-devel <xen-devel@lists.xen.org>, Jan Beulich <jbeulich@suse.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Daniel De Graaf <dgdegra@tycho.nsa.gov>
List-Id: xen-devel@lists.xenproject.org

On 06/24/2015 07:44 PM, Lengyel, Tamas wrote:
>> +    if ( altp2m_active )
>> +    {
>> +        if ( altp2mhvm_hap_nested_page_fault(v, gpa, gla, npfec, &p2m) ==
>> 1 )
>> +        {
>> +            /* entry was lazily copied from host -- retry */
>>
> 
> So I'm not fully following this logic here. I can see that the altp2m entry
> got copied from the host. Why is there a need for the retry, why not just
> continue?

At this point the EPT's that the hardware is using have been made valid
by software, but the hardware has already failed the access so you have
to restart the operation. This isn't in any way specific to altp2m,
it's how page fault logic works generally.

Ed