[Intel-xe] [PATCH v4 4/5] drm/xe/pat: annotate pat_index with coherency mode

Matthew Auld matthew.auld at intel.com
Wed Sep 27 11:00:10 UTC 2023


Future uapi needs to give userspace the ability to select the pat_index
for a given vm_bind. However we need to be able to extract the coherency
mode from the provided pat_index to ensure it matches the coherency mode
set at object creation. There are various security reasons for why this
matters.  However the pat_index itself is very platform specific, so
seems reasonable to annotate each platform definition of the pat table.
On some older platforms there is no explicit coherency mode, so we just
pick whatever makes sense.

v2:
  - Simplify with COH_AT_LEAST_1_WAY
  - Add some kernel-doc
v3 (Matt Roper):
  - Some small tweaks
v4:
  - Rebase

Bspec: 45101, 44235 #xe
Bspec: 70552, 71582, 59400 #xe2
Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Pallavi Mishra <pallavi.mishra at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Filip Hazubski <filip.hazubski at intel.com>
Cc: Carl Zhang <carl.zhang at intel.com>
Cc: Effie Yu <effie.yu at intel.com>
Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/xe/xe_device_types.h |  2 +-
 drivers/gpu/drm/xe/xe_pat.c          | 62 ++++++++++++++++------------
 drivers/gpu/drm/xe/xe_pat.h          | 28 +++++++++++++
 3 files changed, 65 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 7d0f2109c23a..18af9e29f42f 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -340,7 +340,7 @@ struct xe_device {
 		/** Internal operations to abstract platforms */
 		const struct xe_pat_ops *ops;
 		/** PAT table to program in the HW */
-		const u32 *table;
+		const struct xe_pat_table_entry *table;
 		/** Number of PAT entries */
 		int n_entries;
 		u32 idx[__XE_CACHE_LEVEL_COUNT];
diff --git a/drivers/gpu/drm/xe/xe_pat.c b/drivers/gpu/drm/xe/xe_pat.c
index 2c759ffa35ef..5943798b1f02 100644
--- a/drivers/gpu/drm/xe/xe_pat.c
+++ b/drivers/gpu/drm/xe/xe_pat.c
@@ -5,6 +5,8 @@
 
 #include "xe_pat.h"
 
+#include <drm/xe_drm.h>
+
 #include "regs/xe_reg_defs.h"
 #include "xe_gt.h"
 #include "xe_gt_mcr.h"
@@ -33,51 +35,58 @@
 #define XELP_PAT_UC				REG_FIELD_PREP(XELP_MEM_TYPE_MASK, 0)
 
 struct xe_pat_ops {
-	void (*program_graphics)(struct xe_gt *gt, const u32 table[], int n_entries);
-	void (*program_media)(struct xe_gt *gt, const u32 table[], int n_entries);
+	void (*program_graphics)(struct xe_gt *gt, const struct xe_pat_table_entry table[], int n_entries);
+	void (*program_media)(struct xe_gt *gt, const struct xe_pat_table_entry table[], int n_entries);
 };
 
-static const u32 xelp_pat_table[] = {
-	[0] = XELP_PAT_WB,
-	[1] = XELP_PAT_WC,
-	[2] = XELP_PAT_WT,
-	[3] = XELP_PAT_UC,
+static const struct xe_pat_table_entry xelp_pat_table[] = {
+	[0] = { XELP_PAT_WB, XE_GEM_COH_AT_LEAST_1WAY },
+	[1] = { XELP_PAT_WC, XE_GEM_COH_NONE },
+	[2] = { XELP_PAT_WT, XE_GEM_COH_NONE },
+	[3] = { XELP_PAT_UC, XE_GEM_COH_NONE },
 };
 
-static const u32 xehpc_pat_table[] = {
-	[0] = XELP_PAT_UC,
-	[1] = XELP_PAT_WC,
-	[2] = XELP_PAT_WT,
-	[3] = XELP_PAT_WB,
-	[4] = XEHPC_PAT_CLOS(1) | XELP_PAT_WT,
-	[5] = XEHPC_PAT_CLOS(1) | XELP_PAT_WB,
-	[6] = XEHPC_PAT_CLOS(2) | XELP_PAT_WT,
-	[7] = XEHPC_PAT_CLOS(2) | XELP_PAT_WB,
+static const struct xe_pat_table_entry xehpc_pat_table[] = {
+	[0] = { XELP_PAT_UC, XE_GEM_COH_NONE },
+	[1] = { XELP_PAT_WC, XE_GEM_COH_NONE },
+	[2] = { XELP_PAT_WT, XE_GEM_COH_NONE },
+	[3] = { XELP_PAT_WB, XE_GEM_COH_AT_LEAST_1WAY },
+	[4] = { XEHPC_PAT_CLOS(1) | XELP_PAT_WT, XE_GEM_COH_NONE },
+	[5] = { XEHPC_PAT_CLOS(1) | XELP_PAT_WB, XE_GEM_COH_AT_LEAST_1WAY },
+	[6] = { XEHPC_PAT_CLOS(2) | XELP_PAT_WT, XE_GEM_COH_NONE },
+	[7] = { XEHPC_PAT_CLOS(2) | XELP_PAT_WB, XE_GEM_COH_AT_LEAST_1WAY },
 };
 
-static const u32 xelpg_pat_table[] = {
-	[0] = XELPG_PAT_0_WB,
-	[1] = XELPG_PAT_1_WT,
-	[2] = XELPG_PAT_3_UC,
-	[3] = XELPG_PAT_0_WB | XELPG_2_COH_1W,
-	[4] = XELPG_PAT_0_WB | XELPG_3_COH_2W,
+static const struct xe_pat_table_entry xelpg_pat_table[] = {
+	[0] = { XELPG_PAT_0_WB, XE_GEM_COH_NONE },
+	[1] = { XELPG_PAT_1_WT, XE_GEM_COH_NONE },
+	[2] = { XELPG_PAT_3_UC, XE_GEM_COH_NONE },
+	[3] = { XELPG_PAT_0_WB | XELPG_2_COH_1W, XE_GEM_COH_AT_LEAST_1WAY },
+	[4] = { XELPG_PAT_0_WB | XELPG_3_COH_2W, XE_GEM_COH_AT_LEAST_1WAY },
 };
 
-static void program_pat(struct xe_gt *gt, const u32 table[], int n_entries)
+u16 xe_pat_index_get_coh_mode(struct xe_device *xe, u16 pat_index)
+{
+	WARN_ON(pat_index >= xe->pat.n_entries);
+	return xe->pat.table[pat_index].coh_mode;
+}
+
+static void program_pat(struct xe_gt *gt, const struct xe_pat_table_entry table[], int n_entries)
 {
 	for (int i = 0; i < n_entries; i++) {
 		struct xe_reg reg = XE_REG(_PAT_INDEX(i));
 
-		xe_mmio_write32(gt, reg, table[i]);
+		xe_mmio_write32(gt, reg, table[i].value);
 	}
 }
 
-static void program_pat_mcr(struct xe_gt *gt, const u32 table[], int n_entries)
+static void program_pat_mcr(struct xe_gt *gt, const struct xe_pat_table_entry table[],
+			    int n_entries)
 {
 	for (int i = 0; i < n_entries; i++) {
 		struct xe_reg_mcr reg_mcr = XE_REG_MCR(_PAT_INDEX(i));
 
-		xe_gt_mcr_multicast_write(gt, reg_mcr, table[i]);
+		xe_gt_mcr_multicast_write(gt, reg_mcr, table[i].value);
 	}
 }
 
@@ -125,6 +134,7 @@ void xe_pat_init_early(struct xe_device *xe)
 		xe->pat.idx[XE_CACHE_WT] = 2;
 		xe->pat.idx[XE_CACHE_WB] = 0;
 	} else if (GRAPHICS_VERx100(xe) <= 1210) {
+		WARN_ON_ONCE(!IS_DGFX(xe) && !xe->info.has_llc);
 		xe->pat.ops = &xelp_pat_ops;
 		xe->pat.table = xelp_pat_table;
 		xe->pat.n_entries = ARRAY_SIZE(xelp_pat_table);
diff --git a/drivers/gpu/drm/xe/xe_pat.h b/drivers/gpu/drm/xe/xe_pat.h
index 744318cab69b..4032c0ef975c 100644
--- a/drivers/gpu/drm/xe/xe_pat.h
+++ b/drivers/gpu/drm/xe/xe_pat.h
@@ -6,9 +6,29 @@
 #ifndef _XE_PAT_H_
 #define _XE_PAT_H_
 
+#include <linux/types.h>
+
 struct xe_gt;
 struct xe_device;
 
+/**
+ * struct xe_pat_table_entry - The pat_index encoding and other meta information.
+ */
+struct xe_pat_table_entry {
+	/**
+	 * @value: The platform specific value encoding the various memory
+	 * attributes (this maps to some fixed pat_index). So things like
+	 * caching, coherency, compression etc can be encoded here.
+	 */
+	u32 value;
+
+	/**
+	 * @coh_mode: The GPU coherency mode that @value maps to. Either
+	 * XE_GEM_COH_NONE or XE_GEM_COH_AT_LEAST_1WAY.
+	 */
+	u16 coh_mode;
+};
+
 /**
  * xe_pat_init_early - SW initialization, setting up data based on device
  * @xe: xe device
@@ -21,4 +41,12 @@ void xe_pat_init_early(struct xe_device *xe);
  */
 void xe_pat_init(struct xe_gt *gt);
 
+/**
+ * xe_pat_index_get_coh_mode - Extract the coherency mode for the given
+ * pat_index.
+ * @xe: xe device
+ * @pat_index: The pat_index to query
+ */
+u16 xe_pat_index_get_coh_mode(struct xe_device *xe, u16 pat_index);
+
 #endif
-- 
2.41.0



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