Re: [PATCH 6/7] KVM: MMU: Simplify spte fetch() function

[Avi Kivity <avi@redhat.com>]

On 07/12/2010 08:08 AM, Xiao Guangrong wrote:
>
> Avi Kivity wrote:
>
>    
>> -		if (is_shadow_present_pte(*sptep)&&  !is_large_pte(*sptep)
>> -		&&  level == gw->level)
>> -			validate_direct_spte(vcpu, sptep, direct_access);
>>      
> ......
>
>    
>> +		link_shadow_page(sptep, sp);
>> +	}
>> +
>> +	for (;
>> +	     shadow_walk_okay(&iterator)&&  iterator.level>  hlevel;
>> +	     shadow_walk_next(&iterator)) {
>> +		gfn_t direct_gfn;
>> +
>> +		level = iterator.level;
>> +		sptep = iterator.sptep;
>>
>>   		drop_spte_if_large(vcpu, sptep);
>>
>>   		if (is_shadow_present_pte(*sptep))
>>   			continue;
>>
>> -		if (level<= gw->level) {
>> -			direct = 1;
>> -			access = direct_access;
>> -
>> -			/*
>> -			 * It is a large guest pages backed by small host pages,
>> -			 * So we set @direct(@sp->role.direct)=1, and set
>> -			 * @table_gfn(@sp->gfn)=the base page frame for linear
>> -			 * translations.
>> -			 */
>> -			table_gfn = gw->gfn&  ~(KVM_PAGES_PER_HPAGE(level) - 1);
>> -		} else {
>> -			direct = 0;
>> -			table_gfn = gw->table_gfn[level - 2];
>> -		}
>> -		sp = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
>> -					       direct, access, sptep);
>> -		if (!direct)
>> -			if (!FNAME(validate_indirect_spte)(vcpu, sptep, sp,
>> -							   gw, level)) {
>> -				kvm_release_pfn_clean(pfn);
>> -				sptep = NULL;
>> -				break;
>> -			}
>> +		validate_direct_spte(vcpu, sptep, direct_access);
>>      
> Need validate_direct_spte() only when 'level == gw->level'
>
>    

That is true (and this is a change from the current code), but level < 
gw->level will be very rare (1G pages backed by 4k pages) so I don't 
mind the extra check.



-- 
error compiling committee.c: too many arguments to function