drm/imagination: Fix error path in pvr_vm_create_context

It is possible to double free the vm_ctx->mmu_ctx object in this
function.

    630 err_page_table_destroy:
--> 631         pvr_mmu_context_destroy(vm_ctx->mmu_ctx);

The pvr_vm_context_put() function does:

        kref_put(&vm_ctx->ref_count, pvr_vm_context_release);

Here the pvr_vm_context_release() will call:

        pvr_mmu_context_destroy(vm_ctx->mmu_ctx);

Refactor to an unwind style.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231213144431.94956-2-donald.robson@imgtec.com

drm/imagination: Fix ERR_PTR test on pointer to pointer.

drivers/gpu/drm/imagination/pvr_vm.c:631 pvr_vm_create_context()
error: 'vm_ctx->mmu_ctx' dereferencing possible ERR_PTR()

612 vm_ctx->mmu_ctx = pvr_mmu_context_create(pvr_dev);
613 err = PTR_ERR_OR_ZERO(&vm_ctx->mmu_ctx);
^
The address is never an error pointer so this will always return 0.
Remove the ampersand.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231213144431.94956-1-donald.robson@imgtec.com

drm/imagination: vm: Fix heap lookup condition

When conditionally checking for heap existence of a certian address in
pvr_vm_bind_op_map_init the condition whether the map request comes from a
user is incorrect: The context must not be the kernel-context to be a
user(space) context and should be looked up in pvr_heaps.

That makes addresses coming from userspace not being verfied against the
defined ranges and prevents firmware loading for meta cores.

Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Alex Bee <knaerzche@gmail.com>
Reviewed-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231208170856.1748413-1-knaerzche@gmail.com

drm/imagination: vm: make use of GPUVM's drm_exec helper

Make use of GPUVM's drm_exec helper functions preventing direct access
to GPUVM internal data structures, such as the external object list.

This is especially important to ensure following the locking rules
around the GPUVM external object list.

Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Reviewed-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231129220835.297885-3-dakr@redhat.com

drm/imagination: Removed unused function to_pvr_vm_gpuva()

This function is now unused, hence it causes a compiler warning.

drivers/gpu/drm/imagination/pvr_vm.c:112:22: warning: unused function 'to_pvr_vm_gpuva' [-Wunused-function]
112 | struct pvr_vm_gpuva *to_pvr_vm_gpuva(struct drm_gpuva *gpuva)
| ^

Remove the function for now.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311242159.hh8MWiAm-lkp@intel.com/
Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231130160017.259902-5-donald.robson@imgtec.com

drm/imagination: pvr_gpuvm_free() now static

The function below is used only within this source file, but is not static.

drivers/gpu/drm/imagination/pvr_vm.c:542:6: error: no previous prototype for 'pvr_gpuvm_free' [-Werror=missing-prototypes]
542 | void pvr_gpuvm_free(struct drm_gpuvm *gpuvm)

Make it static.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311242159.hh8MWiAm-lkp@intel.com/
Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Link: https://lore.kernel.org/r/20231130160017.259902-4-donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drm/imagination: Numerous documentation fixes.

Some reported by Stephen Rothwell. The rest were found by running the
kernel-doc build script.
Some indentation fixes.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311241526.Y2WZeUau-lkp@intel.com/
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231128173507.95119-1-donald.robson@imgtec.com

drm/imagination: vm: fix drm_gpuvm reference count

The driver specific reference count indicates whether the VM should be
teared down, whereas GPUVM's reference count indicates whether the VM
structure can finally be freed.

Hence, free the VM structure in pvr_gpuvm_free() and drop the last
GPUVM reference after tearing down the VM. Generally, this prevents
lifetime issues such as the VM being freed as long as drm_gpuvm_bo
structures still hold references to the VM.

Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Reviewed-by: Donald Robson <donald.robson@imgtec.com>
Tested-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231124233650.152653-4-dakr@redhat.com

drm/imagination: vm: check for drm_gpuvm_range_valid()

Extend pvr_device_addr_and_size_are_valid() by the corresponding GPUVM
sanity checks. This includes a, previously missing, overflow check for
the base address and size of the requested mapping.

Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Reviewed-by: Donald Robson <donald.robson@imgtec.com>
Tested-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231124233650.152653-3-dakr@redhat.com

drm/imagination: vm: prevent duplicate drm_gpuvm_bo instances

Use drm_gpuvm_bo_obtain() instead of drm_gpuvm_bo_create(). The latter
should only be used in conjunction with drm_gpuvm_bo_obtain_prealloc().

drm_gpuvm_bo_obtain() re-uses existing instances of a given VM and BO
combination, whereas drm_gpuvm_bo_create() would always create a new
instance of struct drm_gpuvm_bo and hence leave us with duplicates.

Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code")
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Reviewed-by: Donald Robson <donald.robson@imgtec.com>
Tested-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231124233650.152653-2-dakr@redhat.com

drm/imagination: Implement firmware infrastructure and META FW support

The infrastructure includes parsing of the firmware image, initialising
FW-side structures, handling the kernel and firmware command
ringbuffers and starting & stopping the firmware processor.

This patch also adds the necessary support code for the META firmware
processor.

Changes since v8:
- Fix documentation for pvr_fwccb_process()
- Corrected license identifiers

Changes since v6:
- Add a minimum retry count to pvr_kccb_reserve_slot_sync()

Changes since v5:
- Add workaround for BRN 71242
- Attempt to recover GPU on MMU flush command failure

Changes since v4:
- Remove use of drm_gem_shmem_get_pages()
- Remove interrupt resource name

Changes since v3:
- Hard reset FW processor on watchdog timeout
- Switch to threaded IRQ
- Rework FW object creation/initialisation to aid hard reset
- Added MODULE_FIRMWARE()
- Use drm_dev_{enter,exit}

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Link: https://lore.kernel.org/r/bb52a8dc84f296b37dc6668dfe8fbaf2ba551139.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drm/imagination: Add GEM and VM related code

Add a GEM implementation based on drm_gem_shmem, and support code for the
PowerVR GPU MMU. The GPU VA manager is used for address space management.

Changes since v8:
- Updated for changes to drm_gpuvm
- Switched to dma_resv locking for vm ops
- Removed linked lists for collecting BOs in vm_context and for freeing
after ops. This is now done internally in drm_gpuvm
- Corrected license identifiers

Changes since v7:
- kernel-doc fixes
- Remove prefixes from DRM_PVR_BO_* flags
- CREATE_BO ioctl now returns an error if provided size isn't page aligned
- Optimised MMU flushes

Changes since v6:
- Don't initialise kernel_vm_ctx when using MIPS firmware processor
- Rename drm_gpuva_manager uses to drm_gpuvm
- Sync GEM object to device on creation

Changes since v5:
- Use WRITE_ONCE() when writing to page tables
- Add memory barriers to page table insertion
- Fixed double backing page alloc on page table objects
- Fix BO mask checks in DRM_IOCTL_PVR_CREATE_BO handler
- Document use of pvr_page_table_*_idx when preallocing page table objs
- Remove pvr_vm_gpuva_mapping_init()
- Remove NULL check for unmap op in remap function
- Protect gem object with mutex during drm_gpuva_link/unlink
- Defer free or release of page table pages until after TLB flush
- Use drm_gpuva_op_remap_get_unmap_range() helper

Changes since v4:
- Correct sync function in vmap/vunmap function documentation
- Update for upstream GPU VA manager
- Fix missing frees when unmapping drm_gpuva objects
- Always zero GEM BOs on creation

Changes since v3:
- Split MMU and VM code
- Register page table allocations with kmemleak
- Use drm_dev_{enter,exit}

Changes since v2:
- Use GPU VA manager
- Use drm_gem_shmem

Co-developed-by: Matt Coster <matt.coster@imgtec.com>
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Co-developed-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Link: https://lore.kernel.org/r/3c96dd170efe759b73897e3675d7310a7c4b06d0.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>