Re: [PATCH v3 10/15] intel-iommu: Implement IOMMU_ATTR_MAX_IOVA get_attr() attribute

[Joao Martins]

On 30/05/2023 22:45, Philippe Mathieu-Daudé wrote:
> On 30/5/23 19:59, Joao Martins wrote:
>> From: Avihai Horon <avihaih@nvidia.com>
>>
>> Implement get_attr() method and use the address width property to report
>> the IOMMU_ATTR_MAX_IOVA attribute.
>>
>> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> ---
>>   hw/i386/intel_iommu.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index 1906f3a67960..829dd6eadc6c 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -3876,6 +3876,13 @@ static int vtd_iommu_get_attr(IOMMUMemoryRegion 
>> *iommu_mr,
>>           *enabled = s->dma_translation;
>>           break;
>>       }
>> +    case IOMMU_ATTR_MAX_IOVA:
>> +    {
>> +        hwaddr *max_iova = data;
> 
> Shouldn't we cast to uintptr_t to be safe?
> 
Perhaps you mean something like this:

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 829dd6eadc6c..479307f1228f 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3878,7 +3878,7 @@ static int vtd_iommu_get_attr(IOMMUMemoryRegion *iommu_mr,
     }
     case IOMMU_ATTR_MAX_IOVA:
     {
-        hwaddr *max_iova = data;
+        hwaddr *max_iova = (hwaddr *)(uintptr_t) data;

         *max_iova = (1ULL << s->aw_bits) - 1;
         break;

I guess the thinking is to prevent 32-bit failures.

>> +        *max_iova = (1ULL << s->aw_bits) - 1;
> 
> Alternatively:
> 
>            *max_iova = MAKE_64BIT_MASK(0, s->aw_bits);
> 

I'll switch to your suggestion. Wasn't aware of this macro :)

>> +        break;
>> +    }
>>       default:
>>           ret = -EINVAL;
>>           break;
>