[Intel-gfx] [PATCH 1/3] drm-uapi: define interface to kernel for scratch page read

[Rogovin, Kevin]

Sighs, I do not know why git send-email made this into two threads, but there it is.

Worse, the second patch was from an older version; the one posted lacks the write to the
scratch page with noise.

At any rate, the thing is also on github at https://github.com/krogueintel/asem/tree/out-of-bounds-write-detect 
which has the initialization of the scratch page with noise.

-Kevin

-----Original Message-----
From: Rogovin, Kevin 
Sent: Tuesday, December 5, 2017 9:48 AM
To: intel-gfx at lists.freedesktop.org
Cc: Rogovin, Kevin <kevin.rogovin at intel.com>
Subject: [PATCH 1/3] drm-uapi: define interface to kernel for scratch page read

From: Kevin Rogovin <kevin.rogovin at intel.com>

---
 include/drm-uapi/i915_drm.h | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h index 890df227ae..3a9c3a2d0c 100644
--- a/include/drm-uapi/i915_drm.h
+++ b/include/drm-uapi/i915_drm.h
@@ -262,6 +262,8 @@ typedef struct _drm_i915_sarea {
 #define DRM_I915_PERF_OPEN		0x36
 #define DRM_I915_PERF_ADD_CONFIG	0x37
 #define DRM_I915_PERF_REMOVE_CONFIG	0x38
+#define DRM_I915_READ_SCRATCH_PAGE      0x39
+#define DRM_I915_WRITE_SCRATCH_PAGE     0x40
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -319,6 +321,8 @@ typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_PERF_OPEN	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_OPEN, struct drm_i915_perf_open_param)
 #define DRM_IOCTL_I915_PERF_ADD_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_ADD_CONFIG, struct drm_i915_perf_oa_config)
 #define DRM_IOCTL_I915_PERF_REMOVE_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_REMOVE_CONFIG, __u64)
+#define DRM_IOCTL_I915_READ_SCRATCH_PAGE        DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_READ_SCRATCH_PAGE, struct drm_i915_scratch_page)
+#define DRM_IOCTL_I915_WRITE_SCRATCH_PAGE       DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_WRITE_SCRATCH_PAGE, struct drm_i915_scratch_page)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -1535,6 +1539,33 @@ struct drm_i915_perf_oa_config {
 	__u64 flex_regs_ptr;
 };
 
+/**
+ * Structure to read/write scratch page of PPGTT. Read and writing
+ * values are not reliable unless the calling application guarantees
+ * that no batchbuffer that could read or write the scratch is in
+ * flight using the PPGTT between the time the ioctl is issued and
+ * it returns.
+ */
+struct drm_i915_scratch_page {
+   /**
+    * size in bytes of the backing store pointed to by buffer_ptr;
+    * kernel will return the actual size of the scratch page in
+    * this field as well.
+    */
+   __u32 buffer_size;
+
+   /**
+    * Pointer data with which to upload to or download from the
+    * scratch page; if the buffer size behind buffer_ptr is
+    * smaller than the scratch page size, then only the first
+    * buffer_size bytes are read or written. If the scratch
+    * page size is greater than buffer_size, then the bytes
+    * past the scratch page size in buffer behind bufer_ptr
+    * are not read or writte.
+    */
+   __u64 buffer_ptr;
+};
+
 #if defined(__cplusplus)
 }
 #endif
--
2.15.0