iommu: Prepare IOMMU domain for IOPF

This adds some mechanisms around the iommu_domain so that the I/O page
fault handling framework could route a page fault to the domain and
call the fault handler from it.

Add pointers to the page fault handler and its private data in struct
iommu_domain. The fault handler will be called with the private data
as a parameter once a page fault is routed to the domain. Any kernel
component which owns an iommu domain could install handler and its
private parameter so that the page fault could be further routed and
handled.

This also prepares the SVA implementation to be the first consumer of
the per-domain page fault handling model. The I/O page fault handler
for SVA is copied to the SVA file with mmget_not_zero() added before
mmap_read_lock().

Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Tested-by: Tony Zhu <tony.zhu@intel.com>
Link: https://lore.kernel.org/r/20221031005917.45690-12-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index c337ef1c97bc..7d2648058e43 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -98,6 +98,9 @@ struct iommu_domain {
 	unsigned long pgsize_bitmap;	/* Bitmap of page sizes in use */
 	struct iommu_domain_geometry geometry;
 	struct iommu_dma_cookie *iova_cookie;
+	enum iommu_page_response_code (*iopf_handler)(struct iommu_fault *fault,
+						      void *data);
+	void *fault_data;
 	union {
 		struct {
 			iommu_fault_handler_t handler;