gpu: nvgpu: Add get/set PTE routines

Add new routines for accessing and modifying PTEs in situ. They are:

  __nvgpu_pte_words()
  __nvgpu_get_pte()
  __nvgpu_set_pte()

All the details of modifying a page table entry are handled within.

Note, however, that these routines will not build page tables. If a PTE
does not exist then said PTE will not be created. Instead -EINVAL will
be returned. But, keep in mind, a PTE marked as invalid still exists.
So this API can be used to mark an invalid PTE valid.

JIRA NVGPU-30

Change-Id: Ic8615f209a0c4eb6fa64af9abadcfb3b2c11ee73
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1510447
Reviewed-by: Automatic_Commit_Validation_User
Tested-by: Seema Khowala <seemaj@nvidia.com>
Reviewed-by: Seema Khowala <seemaj@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Vijayakumar Subbu <vsubbu@nvidia.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/gmmu.h b/drivers/gpu/nvgpu/include/nvgpu/gmmu.h
index 92e5eb5f..de129a5f 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/gmmu.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/gmmu.h
@@ -273,6 +273,56 @@ static inline void pd_write(struct gk20a *g, struct nvgpu_gmmu_pd *pd,
         nvgpu_mem_wr32(g, pd->mem, (pd->mem_offs / sizeof(u32)) + w, data);
 }
 
+/**
+ * __nvgpu_pte_words - Compute number of words in a PTE.
+ *
+ * @g  - The GPU.
+ *
+ * This computes and returns the size of a PTE for the passed chip.
+ */
+u32 __nvgpu_pte_words(struct gk20a *g);
+
+/**
+ * __nvgpu_get_pte - Get the contents of a PTE by virtual address
+ *
+ * @g     - The GPU.
+ * @vm    - VM to look in.
+ * @vaddr - GPU virtual address.
+ * @pte   - [out] Set to the contents of the PTE.
+ *
+ * Find a PTE in the passed VM based on the passed GPU virtual address. This
+ * will @pte with a copy of the contents of the PTE. @pte must be an array of
+ * u32s large enough to contain the PTE. This can be computed using
+ * __nvgpu_pte_words().
+ *
+ * If you wish to write to this PTE then you may modify @pte and then use the
+ * __nvgpu_set_pte().
+ *
+ * This function returns 0 if the PTE is found and -EINVAL otherwise.
+ */
+int __nvgpu_get_pte(struct gk20a *g, struct vm_gk20a *vm, u64 vaddr, u32 *pte);
+
+/**
+ * __nvgpu_set_pte - Set a PTE based on virtual address
+ *
+ * @g     - The GPU.
+ * @vm    - VM to look in.
+ * @vaddr - GPU virtual address.
+ * @pte   - The contents of the PTE to write.
+ *
+ * Find a PTE and overwrite the contents of that PTE with the passed in data
+ * located in @pte. If the PTE does not exist then no writing will happen. That
+ * is this function will not fill out the page tables for you. The expectation
+ * is that the passed @vaddr has already been mapped and this is just modifying
+ * the mapping (for instance changing invalid to valid).
+ *
+ * @pte must contain at least the required words for the PTE. See
+ * __nvgpu_pte_words().
+ *
+ * This function returns 0 on success and -EINVAL otherwise.
+ */
+int __nvgpu_set_pte(struct gk20a *g, struct vm_gk20a *vm, u64 vaddr, u32 *pte);
+
 
 /*
  * Internal debugging routines. Probably not something you want to use.