From fa83433c92e340822a056a610a4fa2063a3db304 Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Wed, 2 Oct 2019 12:42:41 -0700 Subject: iommu: Add I/O ASID allocator Some devices might support multiple DMA address spaces, in particular those that have the PCI PASID feature. PASID (Process Address Space ID) allows to share process address spaces with devices (SVA), partition a device into VM-assignable entities (VFIO mdev) or simply provide multiple DMA address space to kernel drivers. Add a global PASID allocator usable by different drivers at the same time. Name it I/O ASID to avoid confusion with ASIDs allocated by arch code, which are usually a separate ID space. The IOASID space is global. Each device can have its own PASID space, but by convention the IOMMU ended up having a global PASID space, so that with SVA, each mm_struct is associated to a single PASID. The allocator is primarily used by IOMMU subsystem but in rare occasions drivers would like to allocate PASIDs for devices that aren't managed by an IOMMU, using the same ID space as IOMMU. Signed-off-by: Jean-Philippe Brucker Signed-off-by: Jacob Pan Reviewed-by: Jean-Philippe Brucker Reviewed-by: Eric Auger Signed-off-by: Joerg Roedel --- drivers/iommu/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/iommu/Kconfig') diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index e3842eabcfdd..fd50ddffffbf 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -3,6 +3,10 @@ config IOMMU_IOVA tristate +# The IOASID library may also be used by non-IOMMU_API users +config IOASID + tristate + # IOMMU_API always gets selected by whoever wants it. config IOMMU_API bool -- cgit v1.2.3