Re: [patch 2/5] KVM: MMU: make for_each_shadow_entry aware of largepages

From: Marcelo Tosatti <mtosatti@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: kvm@vger.kernel.org, sheng.yang@intel.com
Subject: Re: [patch 2/5] KVM: MMU: make for_each_shadow_entry aware of largepages
Date: Thu, 11 Jun 2009 09:38:54 -0300	[thread overview]
Message-ID: <20090611123854.GA4101@amt.cnet> (raw)
In-Reply-To: <4A2F7B01.90807@redhat.com>

On Wed, Jun 10, 2009 at 12:21:05PM +0300, Avi Kivity wrote:
> Avi Kivity wrote:
>> Marcelo Tosatti wrote:
>>> This way there is no need to add explicit checks in every
>>> for_each_shadow_entry user.
>>>
>>> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>>>
>>> Index: kvm/arch/x86/kvm/mmu.c
>>> ===================================================================
>>> --- kvm.orig/arch/x86/kvm/mmu.c
>>> +++ kvm/arch/x86/kvm/mmu.c
>>> @@ -1273,6 +1273,11 @@ static bool shadow_walk_okay(struct kvm_
>>>  {
>>>      if (iterator->level < PT_PAGE_TABLE_LEVEL)
>>>          return false;
>>> +
>>> +    if (iterator->level == PT_PAGE_TABLE_LEVEL)
>>> +        if (is_large_pte(*iterator->sptep))
>>> +            return false;
>>>
>>>   
>> s/==/>/?
>>
>
> Ah, it's actually fine.  But changing == to >= will make it 1GBpage-ready.

Humpf, better check level explicitly before interpreting bit 7, so lets 
skip this for 1GB pages.