Re: [RFC PATCH v3 06/12] iommu: Split 'addr_merge' argument to iommu_pgsize() into separate parts

[isaacm@codeaurora.org]

On 2021-04-06 04:53, Will Deacon wrote:
> On Mon, Apr 05, 2021 at 12:11:06PM -0700, Isaac J. Manjarres wrote:
>> From: Will Deacon <will@kernel.org>
>> 
>> The 'addr_merge' parameter to iommu_pgsize() is a fabricated address
>> intended to describe the alignment requirements to consider when
>> choosing an appropriate page size. On the iommu_map() path, this 
>> address
>> is the logical OR of the virtual and physical addresses.
>> 
>> Subsequent improvements to iommu_pgsize() will need to check the
>> alignment of the virtual and physical components of 'addr_merge'
>> independently, so pass them in as separate parameters and reconstruct
>> 'addr_merge' locally.
>> 
>> No functional change.
>> 
>> Signed-off-by: Will Deacon <will@kernel.org>
>> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
>> ---
>>  drivers/iommu/iommu.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 9006397b6604..a3bbf7e310b0 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2357,12 +2357,13 @@ phys_addr_t iommu_iova_to_phys(struct 
>> iommu_domain *domain, dma_addr_t iova)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
>> 
>> -static size_t iommu_pgsize(struct iommu_domain *domain,
>> -			   unsigned long addr_merge, size_t size)
>> +static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long 
>> iova,
>> +			   phys_addr_t paddr, size_t size)
>>  {
>>  	unsigned int pgsize_idx;
>>  	unsigned long pgsizes;
>>  	size_t pgsize;
>> +	phys_addr_t addr_merge = paddr | iova;
> 
> Huh, so this was 'unsigned long' before and, given that the 
> pgsize_bitmap
> on the domain is also unsigned long, then I think that's fine. So using
> that would mean you don't need GENMASK_ULL for this guy either.
> 
> Will
Thanks, I will address this in version 4 of the series.

--Isaac
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