linux-kernel - Re: [PATCH v2] iommu/vt-d: Fix a bug in intel_iommu_iova_to

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Message-ID: <ab64969a-5a52-5a22-061b-de57a5ac5627@linux.intel.com>
Date:   Mon, 24 Feb 2020 22:05:04 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Yonghyun Hwang <yonghyun@...gle.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Havard Skinnemoen <hskinnemoen@...gle.com>,
        Deepa Dinamani <deepadinamani@...gle.com>,
        Moritz Fischer <mdf@...nel.org>
Subject: Re: [PATCH v2] iommu/vt-d: Fix a bug in intel_iommu_iova_to_phys()
 for huge page

Hi Joerg and Yonghyun,

I found a problem in the test. I am still working on this. Please hold
on for a while.

Best regards,
baolu

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@...gle.com>
> 
> This fix looks good to me.
> 
> Cc: <stable@...nel.org> # As far back as possible
> Acked-by: Lu Baolu <baolu.lu@...ux.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;
>>   }
>>