drm/amdgpu: Implement mmap as GEM object function

Moving the driver-specific mmap code into a GEM object function allows
for using DRM helpers for various mmap callbacks.

This change resolves several inconsistencies between regular mmap and
prime-based mmap. The vm_ops field in vma is now set for all mmap'ed
areas. Previously it way only set for regular mmap calls, prime-based
mmap used TTM's default vm_ops. The function amdgpu_verify_access() is
no longer being called and therefore removed by this patch.

As a side effect, amdgpu_ttm_vm_ops and amdgpu_ttm_fault() are now
implemented in amdgpu's GEM code.

v4:
	* rebased
v3:
	* rename mmap function to amdgpu_gem_object_mmap() (Christian)
	* remove unnecessary checks from mmap (Christian)
v2:
	* rename amdgpu_ttm_vm_ops and amdgpu_ttm_fault() to
	  amdgpu_gem_vm_ops and amdgpu_gem_fault() (Christian)
	* the check for kfd_bo has meanwhile been removed

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210525151055.8174-3-tzimmermann@suse.de

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 18974bd081f0..73c76a3e2b12 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -32,6 +32,7 @@
 #include <linux/dma-buf.h>
 
 #include <drm/amdgpu_drm.h>
+#include <drm/drm_drv.h>
 #include <drm/drm_gem_ttm_helper.h>
 
 #include "amdgpu.h"
@@ -41,6 +42,46 @@
 
 static const struct drm_gem_object_funcs amdgpu_gem_object_funcs;
 
+static vm_fault_t amdgpu_gem_fault(struct vm_fault *vmf)
+{
+	struct ttm_buffer_object *bo = vmf->vma->vm_private_data;
+	struct drm_device *ddev = bo->base.dev;
+	vm_fault_t ret;
+	int idx;
+
+	ret = ttm_bo_vm_reserve(bo, vmf);
+	if (ret)
+		return ret;
+
+	if (drm_dev_enter(ddev, &idx)) {
+		ret = amdgpu_bo_fault_reserve_notify(bo);
+		if (ret) {
+			drm_dev_exit(idx);
+			goto unlock;
+		}
+
+		 ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
+						TTM_BO_VM_NUM_PREFAULT, 1);
+
+		 drm_dev_exit(idx);
+	} else {
+		ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
+	}
+	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
+		return ret;
+
+unlock:
+	dma_resv_unlock(bo->base.resv);
+	return ret;
+}
+
+static const struct vm_operations_struct amdgpu_gem_vm_ops = {
+	.fault = amdgpu_gem_fault,
+	.open = ttm_bo_vm_open,
+	.close = ttm_bo_vm_close,
+	.access = ttm_bo_vm_access
+};
+
 static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
 {
 	struct amdgpu_bo *robj = gem_to_amdgpu_bo(gobj);
@@ -205,6 +246,18 @@ out_unlock:
 	ttm_eu_backoff_reservation(&ticket, &list);
 }
 
+static int amdgpu_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+	struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+	if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm))
+		return -EPERM;
+	if (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS)
+		return -EPERM;
+
+	return drm_gem_ttm_mmap(obj, vma);
+}
+
 static const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
 	.free = amdgpu_gem_object_free,
 	.open = amdgpu_gem_object_open,
@@ -212,6 +265,8 @@ static const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
 	.export = amdgpu_gem_prime_export,
 	.vmap = drm_gem_ttm_vmap,
 	.vunmap = drm_gem_ttm_vunmap,
+	.mmap = amdgpu_gem_object_mmap,
+	.vm_ops = &amdgpu_gem_vm_ops,
 };
 
 /*