Re: [PATCH v2] iommu/vt-d: Fix a bug in intel_iommu_iova_to_phys() for huge page

Lu Baolu
2020-02-22T13:08:12Z

Hi,

On 2020/2/22 21:05, Lu Baolu wrote:
> Hi,
>
> On 2020/2/21 3:44, Yonghyun Hwang wrote:
>> intel_iommu_iova_to_phys() has a bug when it translates an IOVA for a
>> huge
>> page onto its corresponding physical address. This commit fixes the
>> bug by
>> accomodating the level of page entry for the IOVA and adds IOVA's lower
>> address to the physical address.
>>
>> Signed-off-by: Yonghyun Hwang <yonghyun@google.com>
>
> This fix looks good to me.
>
> Cc: <stable@kernel.org> # As far back as possible

The email address should be: stable@vger.kernel.org.

Sorry about the typo.

Best regards,
baolu

> Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
>
> Best regards,
> baolu
>
>> ---
>>
>> Changes from v1:
>> - level cannot be 0. So, the condition, "if (level > 1)", is removed,
>> which results in a simple code.
>> - a macro, BIT_MASK, is used to have a bit mask
>>
>> ---
>>   drivers/iommu/intel-iommu.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index 932267f49f9a..4fd5c6287b6d 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -5554,7 +5554,9 @@ static phys_addr_t
>> intel_iommu_iova_to_phys(struct iommu_domain *domain,
>>       pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level);
>>       if (pte)
>> -        phys = dma_pte_addr(pte);
>> +        phys = dma_pte_addr(pte) +
>> +            (iova & (BIT_MASK(level_to_offset_bits(level) +
>> +                        VTD_PAGE_SHIFT) - 1));
>>       return phys;
>>   }
>>