[v2] drm/i915: Allow MI_LOAD_REGISTER_REG between whitelisted registers.

Commit Message

Chris Wilson May 6, 2016, 7:50 a.m. UTC

From: Kenneth Graunke <[e-mail]>

Allowing register copies where the source and destination are both
whitelisted should be safe, and is useful.  For example, Mesa uses
this to load the command streamer math registers with data from the
pipeline statistics counters.

v2: Reject writes to OACONTROL (and reads as well :(

Signed-off-by: Kenneth Graunke <[e-mail]>
Reviewed-by: Chris Wilson <[e-mail]> # v1
Signed-off-by: Chris Wilson <[e-mail]>
---
 drivers/gpu/drm/i915/i915_cmd_parser.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

Comments

Kenneth Graunke May 7, 2016, 7:02 a.m. UTC | #1

On Friday, May 6, 2016 8:50:14 AM PDT Chris Wilson wrote:
> From: Kenneth Graunke <[e-mail]>
> 
> Allowing register copies where the source and destination are both
> whitelisted should be safe, and is useful.  For example, Mesa uses
> this to load the command streamer math registers with data from the
> pipeline statistics counters.
> 
> v2: Reject writes to OACONTROL (and reads as well :(
> 
> Signed-off-by: Kenneth Graunke <[e-mail]>
> Reviewed-by: Chris Wilson <[e-mail]> # v1
> Signed-off-by: Chris Wilson <[e-mail]>
> ---
>  drivers/gpu/drm/i915/i915_cmd_parser.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)

Oh, probably a good call to disallow OACONTROL.  Looks good to me.

Thanks for fixing this up, Chris :)

Patch

diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index 69a1ba8ebdfb..c3a760375905 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -215,7 +215,8 @@  static const struct drm_i915_cmd_descriptor hsw_render_cmds[] = {
 	CMD(  MI_RS_CONTEXT,                    SMI,    F,  1,      S  ),
 	CMD(  MI_LOAD_SCAN_LINES_INCL,          SMI,   !F,  0x3F,   M  ),
 	CMD(  MI_LOAD_SCAN_LINES_EXCL,          SMI,   !F,  0x3F,   R  ),
-	CMD(  MI_LOAD_REGISTER_REG,             SMI,   !F,  0xFF,   R  ),
+	CMD(  MI_LOAD_REGISTER_REG,             SMI,   !F,  0xFF,   W,
+	      .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 1 }    ),
 	CMD(  MI_RS_STORE_DATA_IMM,             SMI,   !F,  0xFF,   S  ),
 	CMD(  MI_LOAD_URB_MEM,                  SMI,   !F,  0xFF,   S  ),
 	CMD(  MI_STORE_URB_MEM,                 SMI,   !F,  0xFF,   S  ),
@@ -1098,6 +1099,11 @@  static bool check_cmd(const struct intel_engine_cs *engine,
 					return false;
 				}
 
+				if (desc->cmd.value == MI_LOAD_REGISTER_REG) {
+					DRM_DEBUG_DRIVER("CMD: Rejected LRR to OACONTROL\n");
+					return false;
+				}
+
 				if (desc->cmd.value == MI_LOAD_REGISTER_IMM(1))
 					*oacontrol_set = (cmd[offset + 1] != 0);
 			}
@@ -1113,6 +1119,12 @@  static bool check_cmd(const struct intel_engine_cs *engine,
 					return false;
 				}
 
+				if (desc->cmd.value == MI_LOAD_REGISTER_REG) {
+					DRM_DEBUG_DRIVER("CMD: Rejected LRR to masked register 0x%08X\n",
+							 reg_addr);
+					return false;
+				}
+
 				if (desc->cmd.value == MI_LOAD_REGISTER_IMM(1) &&
 				    (offset + 2 > length ||
 				     (cmd[offset + 1] & reg->mask) != reg->value)) {
@@ -1301,6 +1313,7 @@  int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv)
 	 * 4. L3 atomic chicken bits of HSW_SCRATCH1 and HSW_ROW_CHICKEN3.
 	 * 5. GPGPU dispatch compute indirect registers.
 	 * 6. TIMESTAMP register and Haswell CS GPR registers
+	 * 7. Allow MI_LOAD_REGISTER_REG between whitelisted registers.
 	 */
-	return 6;
+	return 7;
 }