drm/i915: Add test for invalid flag bits in whitelist entries

As per review feedback by Tvrtko, added a check that no invalid bits
are being set in the whitelist flags fields.

Also updated the read/write access definitions to make it clearer that
they are an enum field not a set of single bit flags.
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
CC: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712070745.35239-2-John.C.Harrison@Intel.com

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -1011,6 +1011,20 @@ bool intel_gt_verify_workarounds(struct intel_gt *gt, const char *from)
 	return wa_list_verify(gt->uncore, &gt->i915->gt_wa_list, from);
 }
 
+static inline bool is_nonpriv_flags_valid(u32 flags)
+{
+	/* Check only valid flag bits are set */
+	if (flags & ~RING_FORCE_TO_NONPRIV_MASK_VALID)
+		return false;
+
+	/* NB: Only 3 out of 4 enum values are valid for access field */
+	if ((flags & RING_FORCE_TO_NONPRIV_ACCESS_MASK) ==
+	    RING_FORCE_TO_NONPRIV_ACCESS_INVALID)
+		return false;
+
+	return true;
+}
+
 static void
 whitelist_reg_ext(struct i915_wa_list *wal, i915_reg_t reg, u32 flags)
 {
@@ -1021,6 +1035,9 @@ whitelist_reg_ext(struct i915_wa_list *wal, i915_reg_t reg, u32 flags)
 	if (GEM_DEBUG_WARN_ON(wal->count >= RING_MAX_NONPRIV_SLOTS))
 		return;
 
+	if (GEM_DEBUG_WARN_ON(!is_nonpriv_flags_valid(flags)))
+		return;
+
 	wa.reg.reg |= flags;
 	_wa_add(wal, &wa);
 }
@@ -1028,7 +1045,7 @@ whitelist_reg_ext(struct i915_wa_list *wal, i915_reg_t reg, u32 flags)
 static void
 whitelist_reg(struct i915_wa_list *wal, i915_reg_t reg)
 {
-	whitelist_reg_ext(wal, reg, RING_FORCE_TO_NONPRIV_RW);
+	whitelist_reg_ext(wal, reg, RING_FORCE_TO_NONPRIV_ACCESS_RW);
 }
 
 static void gen9_whitelist_build(struct i915_wa_list *w)
@@ -1109,7 +1126,7 @@ static void cfl_whitelist_build(struct intel_engine_cs *engine)
 	 *   - PS_DEPTH_COUNT_UDW
 	 */
 	whitelist_reg_ext(w, PS_INVOCATION_COUNT,
-			  RING_FORCE_TO_NONPRIV_RD |
+			  RING_FORCE_TO_NONPRIV_ACCESS_RD |
 			  RING_FORCE_TO_NONPRIV_RANGE_4);
 }
 
@@ -1149,20 +1166,20 @@ static void icl_whitelist_build(struct intel_engine_cs *engine)
 		 *   - PS_DEPTH_COUNT_UDW
 		 */
 		whitelist_reg_ext(w, PS_INVOCATION_COUNT,
-				  RING_FORCE_TO_NONPRIV_RD |
+				  RING_FORCE_TO_NONPRIV_ACCESS_RD |
 				  RING_FORCE_TO_NONPRIV_RANGE_4);
 		break;
 
 	case VIDEO_DECODE_CLASS:
 		/* hucStatusRegOffset */
 		whitelist_reg_ext(w, _MMIO(0x2000 + engine->mmio_base),
-				  RING_FORCE_TO_NONPRIV_RD);
+				  RING_FORCE_TO_NONPRIV_ACCESS_RD);
 		/* hucUKernelHdrInfoRegOffset */
 		whitelist_reg_ext(w, _MMIO(0x2014 + engine->mmio_base),
-				  RING_FORCE_TO_NONPRIV_RD);
+				  RING_FORCE_TO_NONPRIV_ACCESS_RD);
 		/* hucStatus2RegOffset */
 		whitelist_reg_ext(w, _MMIO(0x23B0 + engine->mmio_base),
-				  RING_FORCE_TO_NONPRIV_RD);
+				  RING_FORCE_TO_NONPRIV_ACCESS_RD);
 		break;
 
 	default:

drivers/gpu/drm/i915/gt/selftest_workarounds.c

@@ -397,6 +397,10 @@ static bool wo_register(struct intel_engine_cs *engine, u32 reg)
 	enum intel_platform platform = INTEL_INFO(engine->i915)->platform;
 	int i;
 
+	if ((reg & RING_FORCE_TO_NONPRIV_ACCESS_MASK) ==
+	     RING_FORCE_TO_NONPRIV_ACCESS_WR)
+		return true;
+
 	for (i = 0; i < ARRAY_SIZE(wo_registers); i++) {
 		if (wo_registers[i].platform == platform &&
 		    wo_registers[i].reg == reg)
@@ -408,7 +412,8 @@ static bool wo_register(struct intel_engine_cs *engine, u32 reg)
 
 static bool ro_register(u32 reg)
 {
-	if (reg & RING_FORCE_TO_NONPRIV_RD)
+	if ((reg & RING_FORCE_TO_NONPRIV_ACCESS_MASK) ==
+	     RING_FORCE_TO_NONPRIV_ACCESS_RD)
 		return true;
 
 	return false;
@@ -760,8 +765,8 @@ static int read_whitelisted_registers(struct i915_gem_context *ctx,
 		u64 offset = results->node.start + sizeof(u32) * i;
 		u32 reg = i915_mmio_reg_offset(engine->whitelist.list[i].reg);
 
-		/* Clear RD only and WR only flags */
-		reg &= ~(RING_FORCE_TO_NONPRIV_RD | RING_FORCE_TO_NONPRIV_WR);
+		/* Clear access permission field */
+		reg &= ~RING_FORCE_TO_NONPRIV_ACCESS_MASK;
 
 		*cs++ = srm;
 		*cs++ = reg;
@@ -931,7 +936,8 @@ check_whitelisted_registers(struct intel_engine_cs *engine,
 	for (i = 0; i < engine->whitelist.count; i++) {
 		const struct i915_wa *wa = &engine->whitelist.list[i];
 
-		if (i915_mmio_reg_offset(wa->reg) & RING_FORCE_TO_NONPRIV_RD)
+		if (i915_mmio_reg_offset(wa->reg) &
+		    RING_FORCE_TO_NONPRIV_ACCESS_RD)
 			continue;
 
 		if (!fn(engine, a[i], b[i], wa->reg))

drivers/gpu/drm/i915/i915_reg.h

@@ -2522,13 +2522,19 @@ enum i915_power_well_id {
 #define   RING_WAIT_SEMAPHORE	(1 << 10) /* gen6+ */
 
 #define RING_FORCE_TO_NONPRIV(base, i) _MMIO(((base) + 0x4D0) + (i) * 4)
-#define   RING_FORCE_TO_NONPRIV_RW		(0 << 28)    /* CFL+ & Gen11+ */
-#define   RING_FORCE_TO_NONPRIV_RD		(1 << 28)
-#define   RING_FORCE_TO_NONPRIV_WR		(2 << 28)
+#define   RING_FORCE_TO_NONPRIV_ACCESS_RW	(0 << 28)    /* CFL+ & Gen11+ */
+#define   RING_FORCE_TO_NONPRIV_ACCESS_RD	(1 << 28)
+#define   RING_FORCE_TO_NONPRIV_ACCESS_WR	(2 << 28)
+#define   RING_FORCE_TO_NONPRIV_ACCESS_INVALID	(3 << 28)
+#define   RING_FORCE_TO_NONPRIV_ACCESS_MASK	(3 << 28)
 #define   RING_FORCE_TO_NONPRIV_RANGE_1		(0 << 0)     /* CFL+ & Gen11+ */
 #define   RING_FORCE_TO_NONPRIV_RANGE_4		(1 << 0)
 #define   RING_FORCE_TO_NONPRIV_RANGE_16	(2 << 0)
 #define   RING_FORCE_TO_NONPRIV_RANGE_64	(3 << 0)
+#define   RING_FORCE_TO_NONPRIV_RANGE_MASK	(3 << 0)
+#define   RING_FORCE_TO_NONPRIV_MASK_VALID	\
+					(RING_FORCE_TO_NONPRIV_RANGE_MASK \
+					| RING_FORCE_TO_NONPRIV_ACCESS_MASK)
 #define   RING_MAX_NONPRIV_SLOTS  12
 
 #define GEN7_TLB_RD_ADDR	_MMIO(0x4700)