[dpdk-dev] [PATCH v2 2/3] vfio: fix DMA mapping granularity for type1 iova as va

[Burakov, Anatoly]

On 11-Nov-20 5:08 AM, Nithin Dabilpuram wrote:
> On Tue, Nov 10, 2020 at 02:17:39PM +0000, Burakov, Anatoly wrote:
>> On 05-Nov-20 9:04 AM, Nithin Dabilpuram wrote:
>>> Partial unmapping is not supported for VFIO IOMMU type1
>>> by kernel. Though kernel gives return as zero, the unmapped size
>>> returned will not be same as expected. So check for
>>> returned unmap size and return error.
>>>
>>> For IOVA as PA, DMA mapping is already at memseg size
>>> granularity. Do the same even for IOVA as VA mode as
>>> DMA map/unmap triggered by heap allocations,
>>> maintain granularity of memseg page size so that heap
>>> expansion and contraction does not have this issue.
>>>
>>> For user requested DMA map/unmap disallow partial unmapping
>>> for VFIO type1.
>>>
>>> Fixes: 73a639085938 ("vfio: allow to map other memory regions")
>>> Cc: anatoly.burakov at intel.com
>>> Cc: stable at dpdk.org
>>>
>>> Signed-off-by: Nithin Dabilpuram <ndabilpuram at marvell.com>
>>> ---
>>
>> <snip>
>>
>>> @@ -525,12 +528,19 @@ vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
>>>    	/* for IOVA as VA mode, no need to care for IOVA addresses */
>>>    	if (rte_eal_iova_mode() == RTE_IOVA_VA && msl->external == 0) {
>>>    		uint64_t vfio_va = (uint64_t)(uintptr_t)addr;
>>> -		if (type == RTE_MEM_EVENT_ALLOC)
>>> -			vfio_dma_mem_map(default_vfio_cfg, vfio_va, vfio_va,
>>> -					len, 1);
>>> -		else
>>> -			vfio_dma_mem_map(default_vfio_cfg, vfio_va, vfio_va,
>>> -					len, 0);
>>> +		uint64_t page_sz = msl->page_sz;
>>> +
>>> +		/* Maintain granularity of DMA map/unmap to memseg size */
>>> +		for (; cur_len < len; cur_len += page_sz) {
>>> +			if (type == RTE_MEM_EVENT_ALLOC)
>>> +				vfio_dma_mem_map(default_vfio_cfg, vfio_va,
>>> +						 vfio_va, page_sz, 1);
>>> +			else
>>> +				vfio_dma_mem_map(default_vfio_cfg, vfio_va,
>>> +						 vfio_va, page_sz, 0);
>>
>> I think you're mapping the same address here, over and over. Perhaps you
>> meant `vfio_va + cur_len` for the mapping addresses?
> 
> There is a 'vfio_va += page_sz;' in next line right ?
>>
>> -- 
>> Thanks,
>> Anatoly

Oh, right, my apologies. I did need more coffee :D

Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>

-- 
Thanks,
Anatoly