Re: [PATCH 1/10] KVM MMU: fix for calculating gpa in invlpg code

Xiao Guangrong
2010-04-23T12:08:27Z

Avi Kivity wrote:
> On 04/22/2010 09:12 AM, Xiao Guangrong wrote:
>> If the guest is 32-bit, we should use 'quadrant' to adjust gpa
>> offset
>>
>>
>
> Good catch. Only affects kvm_mmu_pte_write(), so I don't think this had
> ill effects other than not prefetching the correct address?
>

Yes

>> @@ -478,9 +478,14 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu,
>> gva_t gva)
>> ((level == PT_DIRECTORY_LEVEL&& is_large_pte(*sptep))) ||
>> ((level == PT_PDPE_LEVEL&& is_large_pte(*sptep)))) {
>> struct kvm_mmu_page *sp = page_header(__pa(sptep));
>> + int offset = 0;
>> +
>> + if (PTTYPE == 32)
>> + offset = sp->role.quadrant<< PT64_LEVEL_BITS;;
>>
>
> Wrong for PT_DIRECTORY_LEVEL (should be q << 8). Also, too many
> semicolons.
>

I guess you mean 'PT64_LEVEL_BITS' not 'PT_DIRECTORY_LEVEL' here :-)

It should be q << 8 here? it hardly understand, take leve = 1 for example,
32-bit guest PTE page table mapping range is 2^(10+12), PAE's PTE page table
mapping range is 2^(9+12), so, i think it's quadrant << 9 here, and other
function like FNAME(prefetch_page), FNAME(sync_page) also are q << 9

Sorry for the double semicolons here, will fix it

Thanks,
Xiao