> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Sent: Tuesday, March 28, 2023 7:22 AM
>
> +/**
> + * @brief
> + * Reserve a PASID from the SVA global number space.
> + *
> + * @param min starting range, inclusive
> + * @param max ending range, inclusive
> + * @return The reserved PASID on success or IOMMU_PASID_INVALID on
> failure.
> + */
> +ioasid_t iommu_sva_reserve_pasid(ioasid_t min, ioasid_t max)
> +{
> + int ret;
> +
> + if (!pasid_valid(min) || !pasid_valid(max) ||
> + min == 0 || max < min)
> + return IOMMU_PASID_INVALID;
> +
> + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max,
> GFP_KERNEL);
> + if (ret < 0)
> + return IOMMU_PASID_INVALID;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_reserve_pasid);
> +
Look at this function. There is no single word about sva except
in the function name.
sva is just one user of global pasids.
when a driver supports sva it has to always use global pasids even
for non-sva usages like dma pasid.
but this doesn't mean that we should build the API around sva.
it's really about global pasids.
let's just call it clearly as iommu_alloc_global_pasid(min, max).
Then we can define a wrapper iommu_reserve_global_pasid(pasid)
as iommu_alloc_global_pasid(pasid, pasid).
for PASID#0 driver calls iommu_reserve_global_pasid(0).
for dma pasid driver calls iommu_alloc_global_pasid() to get a random
one instead of reserving pasid#1.
this would be future proof when the same driver starts to allocate
more pasids for other usages e..g siov.
