Re: [PATCH V7 5/8] arm64/dma-mapping: Implement DMA_ATTR_PRIVILEGED

[Robin Murphy <robin.murphy@arm.com>]

On 13/12/16 14:38, Sricharan wrote:
> Hi Robin,
> 
>> -----Original Message-----
>> From: linux-arm-kernel [mailto:linux-arm-kernel-bounces@lists.infradead.org] On Behalf Of Robin Murphy
>> Sent: Tuesday, December 13, 2016 7:33 PM
>> To: Sricharan R <sricharan@codeaurora.org>; jcrouse@codeaurora.org; pdaly@codeaurora.org; jgebben@codeaurora.org;
>> joro@8bytes.org; linux-kernel@vger.kernel.org; pratikp@codeaurora.org; iommu@lists.linux-foundation.org; tzeng@codeaurora.org;
>> linux-arm-kernel@lists.infradead.org; will.deacon@arm.com; mitchelh@codeaurora.org; vinod.koul@intel.com
>> Cc: dan.j.williams@intel.com
>> Subject: Re: [PATCH V7 5/8] arm64/dma-mapping: Implement DMA_ATTR_PRIVILEGED
>>
>> On 12/12/16 18:38, Sricharan R wrote:
>>> From: Mitchel Humpherys <mitchelh@codeaurora.org>
>>>
>>> The newly added DMA_ATTR_PRIVILEGED is useful for creating mappings that
>>> are only accessible to privileged DMA engines.  Implement it in
>>> dma-iommu.c so that the ARM64 DMA IOMMU mapper can make use of it.
>>>
>>> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>>> Tested-by: Robin Murphy <robin.murphy@arm.com>
>>> Acked-by: Will Deacon <will.deacon@arm.com>
>>> Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
>>> ---
>>>  arch/arm64/mm/dma-mapping.c |  6 +++---
>>>  drivers/iommu/dma-iommu.c   | 10 ++++++++--
>>>  include/linux/dma-iommu.h   |  3 ++-
>>>  3 files changed, 13 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
>>> index 401f79a..ae76ead 100644
>>> --- a/arch/arm64/mm/dma-mapping.c
>>> +++ b/arch/arm64/mm/dma-mapping.c
>>> @@ -557,7 +557,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
>>>  				 unsigned long attrs)
>>>  {
>>>  	bool coherent = is_device_dma_coherent(dev);
>>> -	int ioprot = dma_direction_to_prot(DMA_BIDIRECTIONAL, coherent);
>>> +	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
>>>  	size_t iosize = size;
>>>  	void *addr;
>>>
>>> @@ -711,7 +711,7 @@ static dma_addr_t __iommu_map_page(struct device *dev, struct page *page,
>>>  				   unsigned long attrs)
>>>  {
>>>  	bool coherent = is_device_dma_coherent(dev);
>>> -	int prot = dma_direction_to_prot(dir, coherent);
>>> +	int prot = dma_info_to_prot(dir, coherent, attrs);
>>>  	dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);
>>>
>>>  	if (!iommu_dma_mapping_error(dev, dev_addr) &&
>>> @@ -769,7 +769,7 @@ static int __iommu_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
>>>  		__iommu_sync_sg_for_device(dev, sgl, nelems, dir);
>>>
>>>  	return iommu_dma_map_sg(dev, sgl, nelems,
>>> -			dma_direction_to_prot(dir, coherent));
>>> +				dma_info_to_prot(dir, coherent, attrs));
>>>  }
>>>
>>>  static void __iommu_unmap_sg_attrs(struct device *dev,
>>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>>> index d2a7a46..756d5e0 100644
>>> --- a/drivers/iommu/dma-iommu.c
>>> +++ b/drivers/iommu/dma-iommu.c
>>> @@ -182,16 +182,22 @@ int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
>>>  EXPORT_SYMBOL(iommu_dma_init_domain);
>>>
>>>  /**
>>> - * dma_direction_to_prot - Translate DMA API directions to IOMMU API page flags
>>> + * dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API
>>> + *                    page flags.
>>>   * @dir: Direction of DMA transfer
>>>   * @coherent: Is the DMA master cache-coherent?
>>> + * @attrs: DMA attributes for the mapping
>>>   *
>>>   * Return: corresponding IOMMU API page protection flags
>>>   */
>>> -int dma_direction_to_prot(enum dma_data_direction dir, bool coherent)
>>> +int dma_info_to_prot(enum dma_data_direction dir, bool coherent,
>>> +		     unsigned long attrs)
>>>  {
>>>  	int prot = coherent ? IOMMU_CACHE : 0;
>>>
>>> +	if (attrs & DMA_ATTR_PRIVILEGED)
>>> +		prot |= IOMMU_PRIV;
>>> +
>>>  	switch (dir) {
>>>  	case DMA_BIDIRECTIONAL:
>>>  		return prot | IOMMU_READ | IOMMU_WRITE;
>>
>> ...and applying against -next now also needs this hunk:
>>
>> @@ -639,7 +639,7 @@ dma_addr_t iommu_dma_map_resource(struct device
>> *dev, phys_addr_t phys,
>> 		size_t size, enum dma_data_direction dir, unsigned long attrs)
>> {
>> 	return __iommu_dma_map(dev, phys, size,
>> -			dma_direction_to_prot(dir, false) | IOMMU_MMIO);
>> +			dma_info_to_prot(dir, false, attrs) | IOMMU_MMIO);
>> }
>>
>> void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
>>
>> With those two issues fixed up, I've given the series (applied to
>> next-20161213) a spin on a SMMUv3/PL330 fast model and it still checks out.
>>
> 
> oops, sorry that i missed this in rebase. I can repost now with this fixed,
> 'checks out' you mean something is not working correct ?

No, I mean it _is_ still correct - I guess that's more of an idiom than
I thought :)

Robin.

> 
> Regards,
>  Sricharan  
>