On 03/29/2012 09:07 PM, Avi Kivity wrote:
> On 03/29/2012 11:22 AM, Xiao Guangrong wrote:
>> It can calculate the base gpa of the specified shadow page on any level,
>> let it instead of FNAME(get_level1_sp_gpa)
>>
>>
>> +static gpa_t FNAME(get_sp_gpa)(struct kvm_mmu_page *sp)
>> +{
>
> Maybe worth adding a pte index and calling it get_spte_gpa(), depends on
> the next patches I guess.
>
Yes.
But FNAME(get_sp_gpa) is still needed by FNAME(sync_page) path which sync
all sptes. I will introduce get_spte_gpa() as you mentioned which will be
used in invlpg path and in the later patch.
>> + int offset, shift;
>> +
>> + shift = PAGE_SHIFT - (PT_LEVEL_BITS - PT64_LEVEL_BITS) * sp->role.level;
>> + offset = sp->role.quadrant << shift;
>
> if you add '& ~PAGE_MASK' the compiler may be smart enough to drop the
> whole thing for 64-bit ptes.
>
Sorry. how to do that?
But if you want to remove the unnecessary workload, i will change it
like this:
static gpa_t FNAME(get_sp_gpa)(struct kvm_mmu_page *sp)
{
int offset = 0;
#if PTTYPE == 32
int shift;
shift = PAGE_SHIFT - (PT_LEVEL_BITS - PT64_LEVEL_BITS) * sp->role.level;
offset = sp->role.quadrant << shift;
#endif
return gfn_to_gpa(sp->gfn) + offset;
}
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