From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Dunlap <george.dunlap@eu.citrix.com>
Subject: Re: [PATCH v15 07/19] pvh: Disable unneeded features of
	HVM containers
Date: Tue, 12 Nov 2013 15:08:38 +0000
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To: Jan Beulich <JBeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>, Tim Deegan <tim@xen.org>, Eddie Dong <eddie.dong@intel.com>, Jun Nakajima <jun.nakajima@intel.com>, xen-devel <xen-devel@lists.xenproject.org>
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On 11/12/2013 03:03 PM, Jan Beulich wrote:
>>>> On 12.11.13 at 15:56, George Dunlap <george.dunlap@eu.citrix.com> wrote:
>> On 11/12/2013 01:51 PM, Jan Beulich wrote:
>>>>>> On 11.11.13 at 15:57, George Dunlap <george.dunlap@eu.citrix.com> wrote:
>>>> @@ -1414,6 +1442,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
>>>>        /* For the benefit of 32-bit WinXP (& older Windows) on AMD CPUs,
>>>>         * a fast path for LAPIC accesses, skipping the p2m lookup. */
>>>>        if ( !nestedhvm_vcpu_in_guestmode(v)
>>>> +         && is_hvm_vcpu(v)
>>>
>>> This change looks unnecessary - nestedhvm_vcpu_enter_guestmode()
>>> (the only way by which nestedhvm_vcpu_in_guestmode() could return
>>> other than zero) must obviously never be used on a PVH guest.
>>
>> You've got the polarity of that check wrong -- PVH guests are never in
>> guest mode, therefore !nestedhvm_vcpu_in_guestmode() is always true.
>
> Oh, indeed. In which case I'd slightly prefer !is_pvh_vcpu() here,
> but I guess it's not really significant anyway.

The plan I think is for is_pvh to go away, and instead to have a flag 
indicating whether the guest has / is using a LAPIC.

  -George