[Intel-gfx] [PATCH 1/1] drm/i915/gt: Initialize reserved and unspecified MOCS indices

Lucas De Marchi lucas.demarchi at intel.com
Tue Jun 23 06:15:59 UTC 2020


On Tue, Jun 23, 2020 at 10:29:57AM +0530, Ayaz A Siddiqui wrote:
>In order to avoid functional breakage of mis-programmed applications that
>have grown to depend on unused MOCS entries, we are programming
>those entries to be equal to fully cached ("L3 + LLC") entry.
>
>These reserved and unspecified entries should not be used as they may be
>changed to less performant variants with better coherency in the future
>if more entries are needed.
>
>Cc: Chris Wilson <chris at chris-wilson.co.uk>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Cc: Tomasz Lis <tomasz.lis at intel.com>
>Cc: Matt Roper <matthew.d.roper at intel.com>
>Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>Cc: Francisco Jerez <currojerez at riseup.net>
>Cc: Mathew, Alwin <alwin.mathew at intel.com>
>Cc: Mcguire, Russell W <russell.w.mcguire at intel.com>
>Cc: Spruit, Neil R <neil.r.spruit at intel.com>
>Cc: Zhou, Cheng <cheng.zhou at intel.com>
>Cc: Benemelis, Mike G <mike.g.benemelis at intel.com>
>
>Signed-off-by: Ayaz A Siddiqui <ayaz.siddiqui at intel.com>
>---
> drivers/gpu/drm/i915/gt/intel_mocs.c | 93 ++++++++++++++++++++++++++--
> 1 file changed, 89 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/gt/intel_mocs.c b/drivers/gpu/drm/i915/gt/intel_mocs.c
>index 632e08a4592b2..1089bd5fdba2c 100644
>--- a/drivers/gpu/drm/i915/gt/intel_mocs.c
>+++ b/drivers/gpu/drm/i915/gt/intel_mocs.c
>@@ -234,10 +234,6 @@ static const struct drm_i915_mocs_entry broxton_mocs_table[] = {
> 		   L3_1_UC)
>
> static const struct drm_i915_mocs_entry tgl_mocs_table[] = {
>-	/* Base - Error (Reserved for Non-Use) */
>-	MOCS_ENTRY(0, 0x0, 0x0),
>-	/* Base - Reserved */
>-	MOCS_ENTRY(1, 0x0, 0x0),
>
> 	GEN11_MOCS_ENTRIES,
>
>@@ -265,6 +261,95 @@ static const struct drm_i915_mocs_entry tgl_mocs_table[] = {
> 	MOCS_ENTRY(61,
> 		   LE_1_UC | LE_TC_1_LLC,
> 		   L3_3_WB),
>+
>+	/* NOTE:
>+	 * Reserved and unspecified MOCS indices have been set to (L3 + LCC).
>+	 * These reserved entry should never be used, they may be chanaged
>+	 * to low performant variants with better coherency in the future if
>+	 * more entries are needed.
>+	 */

the whole point of structing this table the way it is is that it doesn't
take more space than needed and we can override values from previous
platforms.

MOCS_ENTRY() will set .used = 1. It seems that what you want is to
actually change the value when .used == 0 is set.

It seems you actually want to set the unused ones to that specific
value. See __init_mocs_table()

Lucas De Marchi

>+
>+	/* Reserved index 0 and 1 */
>+	MOCS_ENTRY(0, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(1, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+
>+	/* Reserved index 16 and 17 */
>+	MOCS_ENTRY(16, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(17, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+
>+	/* Reserved index 24 and 25 */
>+	MOCS_ENTRY(24, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(25, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+
>+	/* Unspecified indices 26 to 47 */
>+	MOCS_ENTRY(26, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(27, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(28, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(29, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(30, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(31, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(32, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(33, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(34, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(35, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(36, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(37, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(38, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(39, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(40, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(41, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(42, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(43, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(44, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(45, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(46, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(47, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+
>+	/* Unspecified indices 52 to 59 */
>+	MOCS_ENTRY(52, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(53, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(54, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(55, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(56, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(57, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(58, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB),
>+	MOCS_ENTRY(59, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
>+		   L3_3_WB)
> };
>
> static const struct drm_i915_mocs_entry icl_mocs_table[] = {
>-- 
>2.26.2
>
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