On 11.05.2018 16:02, Robin Murphy wrote:
> On 08/05/18 19:16, Dmitry Osipenko wrote:
>> Introduce iotlb_sync_map() callback that is invoked in the end of
>> iommu_map(). This new callback allows IOMMU drivers to avoid syncing
>> on mapping of each contiguous chunk and sync only when whole mapping
>> is completed, optimizing performance of the mapping operation.
>
> This looks like a reasonable compromise - for users of
> IO_PGTABLE_QUIRK_TLBI_ON_MAP we can leave the implicit add_flush() in place for
> each individual map call, but at least move the sync() out to this callback,
> which should still be beneficial overall.
>
> Modulo one possible nit below,
>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
>
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>> drivers/iommu/iommu.c | 8 ++++++--
>> include/linux/iommu.h | 1 +
>> 2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index d2aa23202bb9..39b2ee66aa96 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1508,13 +1508,14 @@ static size_t iommu_pgsize(struct iommu_domain *domain,
>> int iommu_map(struct iommu_domain *domain, unsigned long iova,
>> phys_addr_t paddr, size_t size, int prot)
>> {
>> + const struct iommu_ops *ops = domain->ops;
>> unsigned long orig_iova = iova;
>> unsigned int min_pagesz;
>> size_t orig_size = size;
>> phys_addr_t orig_paddr = paddr;
>> int ret = 0;
>> - if (unlikely(domain->ops->map == NULL ||
>> + if (unlikely(ops->map == NULL ||
>> domain->pgsize_bitmap == 0UL))
>> return -ENODEV;
>> @@ -1543,7 +1544,7 @@ int iommu_map(struct iommu_domain *domain, unsigned
>> long iova,
>> pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
>> iova, &paddr, pgsize);
>> - ret = domain->ops->map(domain, iova, paddr, pgsize, prot);
>> + ret = ops->map(domain, iova, paddr, pgsize, prot);
>> if (ret)
>> break;
>> @@ -1552,6 +1553,9 @@ int iommu_map(struct iommu_domain *domain, unsigned
>> long iova,
>> size -= pgsize;
>> }
>> + if (ops->iotlb_sync_map)
>> + ops->iotlb_sync_map(domain);
>
> Is it worth trying to skip this in the error case when we're just going to undo
> it immediately?
I can imagine an IOMMU driver that could handle syncing of mapping differently
from the unmapping, in this case it may not worth skipping sync_map in the error
case.
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