When userspace requests a GEM in AMDGPU_GEM_DOMAIN_MMIO_REMAP, return a
handle to the kernel-owned singleton BO instead of allocating a new one.
Validate inputs (exact PAGE_SIZE, alignment PAGE_SIZE, no extra flags)
and zero the ioctl out-struct on success for a clean echo.
This puts the userspace-visible behavior last, after all internal kernel
plumbing and initialization are in place.
Cc: Christian König <christian.koe...@amd.com>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmu...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 56 +++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index e3f65977eeee..1345e81214e8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -424,6 +424,26 @@ const struct drm_gem_object_funcs amdgpu_gem_object_funcs
= {
.vm_ops = &amdgpu_gem_vm_ops,
};
+/* ========= MMIO remap (HDP flush) GEM handle helper ========= */
+static int amdgpu_gem_get_mmio_remap_handle(struct drm_file *file_priv,
+ struct amdgpu_device *adev,
+ u32 *handle)
+{
+ struct amdgpu_bo *bo = adev->mmio_remap_bo;
+ struct drm_gem_object *gobj;
+ int r;
+
+ if (!bo)
+ return -ENODEV;
+
+ /* Take a temporary ref; the handle creation will hold its own ref. */
+ bo = amdgpu_bo_ref(bo);
+ gobj = &bo->tbo.base;
+ r = drm_gem_handle_create(file_priv, gobj, handle);
+ amdgpu_bo_unref(&bo); /* drops our temporary ref */
+ return r;
+}
+
/*
* GEM ioctls.
*/
@@ -465,6 +485,42 @@ int amdgpu_gem_create_ioctl(struct drm_device *dev, void
*data,
/* always clear VRAM */
flags |= AMDGPU_GEM_CREATE_VRAM_CLEARED;
+ /*
+ * === MMIO remap (HDP flush) fast-path ===
+ * If userspace asks for the MMIO_REMAP domain, don't allocate a new BO.
+ * Return a handle to the singleton BO created at device init.
+ */
+ if (args->in.domains & AMDGPU_GEM_DOMAIN_MMIO_REMAP) {
+ u32 mmio_handle;
+ /* Enforce fixed size & alignment (exactly one page). */
+ if (size && size != PAGE_SIZE)
+ return -EINVAL;
+ if (args->in.alignment && args->in.alignment != PAGE_SIZE)
+ return -EINVAL;
+ /* No extra domain flags for this special object. */
+ if (args->in.domain_flags)
+ return -EINVAL;
+ /* Disallow flags that don't make sense for a fixed I/O page. */
+ if (flags & (AMDGPU_GEM_CREATE_CPU_GTT_USWC |
+ AMDGPU_GEM_CREATE_ENCRYPTED |
+ AMDGPU_GEM_CREATE_DISCARDABLE))
+ return -EINVAL;
+
+ /* Normalize inputs (optional, for user-visible echo/debug). */
+ args->in.bo_size = PAGE_SIZE;
+ args->in.alignment = PAGE_SIZE;
+ args->in.domains = AMDGPU_GEM_DOMAIN_MMIO_REMAP;
+ args->in.domain_flags = 0;
+
+ r = amdgpu_gem_get_mmio_remap_handle(filp, adev, &mmio_handle);
+ if (r)
+ return r;
+
+ memset(args, 0, sizeof(*args));
+ args->out.handle = mmio_handle;
+ return 0;
+ }
+
/* create a gem object to contain this object in */
if (args->in.domains & (AMDGPU_GEM_DOMAIN_GDS |
AMDGPU_GEM_DOMAIN_GWS | AMDGPU_GEM_DOMAIN_OA)) {
--
2.34.1
