drm/amdkfd: Fix bugs regarding CP queue doorbell mask on SOC15

Reserved doorbells for SDMA IH and VCN were not properly masked out
when allocating doorbells for CP user queues. This patch fixed that.
Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c

@@ -196,11 +196,19 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 			gpu_resources.sdma_doorbell[1][i+1] =
 				adev->doorbell_index.sdma_engine[1] + 0x200 + (i >> 1);
 		}
-		/* Doorbells 0x0e0-0ff and 0x2e0-2ff are reserved for
-		 * SDMA, IH and VCN. So don't use them for the CP.
+
+		/* Since SOC15, BIF starts to statically use the
+		 * lower 12 bits of doorbell addresses for routing
+		 * based on settings in registers like
+		 * SDMA0_DOORBELL_RANGE etc..
+		 * In order to route a doorbell to CP engine, the lower
+		 * 12 bits of its address has to be outside the range
+		 * set for SDMA, VCN, and IH blocks.
 		 */
-		gpu_resources.reserved_doorbell_mask = 0x1e0;
-		gpu_resources.reserved_doorbell_val  = 0x0e0;
+		gpu_resources.non_cp_doorbells_start =
+				adev->doorbell_index.first_non_cp;
+		gpu_resources.non_cp_doorbells_end =
+				adev->doorbell_index.last_non_cp;
 
 		kgd2kfd_device_init(adev->kfd.dev, &gpu_resources);
 	}

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

@@ -103,6 +103,17 @@
 
 #define KFD_KERNEL_QUEUE_SIZE 2048
 
+/*
+ * 512 = 0x200
+ * The doorbell index distance between SDMA RLC (2*i) and (2*i+1) in the
+ * same SDMA engine on SOC15, which has 8-byte doorbells for SDMA.
+ * 512 8-byte doorbell distance (i.e. one page away) ensures that SDMA RLC
+ * (2*i+1) doorbells (in terms of the lower 12 bit address) lie exactly in
+ * the OFFSET and SIZE set in registers like BIF_SDMA0_DOORBELL_RANGE.
+ */
+#define KFD_QUEUE_DOORBELL_MIRROR_OFFSET 512
+
+
 /*
  * Kernel module parameter to specify maximum number of supported queues per
  * device

drivers/gpu/drm/amd/amdkfd/kfd_process.c

@@ -607,13 +607,17 @@ static int init_doorbell_bitmap(struct qcm_process_device *qpd,
 	if (!qpd->doorbell_bitmap)
 		return -ENOMEM;
 
-	/* Mask out any reserved doorbells */
-	for (i = 0; i < KFD_MAX_NUM_OF_QUEUES_PER_PROCESS; i++)
-		if ((dev->shared_resources.reserved_doorbell_mask & i) ==
-		    dev->shared_resources.reserved_doorbell_val) {
+	/* Mask out doorbells reserved for SDMA, IH, and VCN on SOC15. */
+	for (i = 0; i < KFD_MAX_NUM_OF_QUEUES_PER_PROCESS / 2; i++) {
+		if (i >= dev->shared_resources.non_cp_doorbells_start
+			&& i <= dev->shared_resources.non_cp_doorbells_end) {
 			set_bit(i, qpd->doorbell_bitmap);
-			pr_debug("reserved doorbell 0x%03x\n", i);
+			set_bit(i + KFD_QUEUE_DOORBELL_MIRROR_OFFSET,
+				qpd->doorbell_bitmap);
+			pr_debug("reserved doorbell 0x%03x and 0x%03x\n", i,
+				i + KFD_QUEUE_DOORBELL_MIRROR_OFFSET);
 		}
+	}
 
 	return 0;
 }

drivers/gpu/drm/amd/include/kgd_kfd_interface.h

@@ -140,17 +140,14 @@ struct kgd2kfd_shared_resources {
 	/* Doorbell assignments (SOC15 and later chips only). Only
 	 * specific doorbells are routed to each SDMA engine. Others
 	 * are routed to IH and VCN. They are not usable by the CP.
-	 *
-	 * Any doorbell number D that satisfies the following condition
-	 * is reserved: (D & reserved_doorbell_mask) == reserved_doorbell_val
-	 *
-	 * KFD currently uses 1024 (= 0x3ff) doorbells per process. If
-	 * doorbells 0x0e0-0x0ff and 0x2e0-0x2ff are reserved, that means
-	 * mask would be set to 0x1e0 and val set to 0x0e0.
 	 */
 	unsigned int sdma_doorbell[2][8];
-	unsigned int reserved_doorbell_mask;
-	unsigned int reserved_doorbell_val;
+
+	/* From SOC15 onward, the doorbell index range not usable for CP
+	 * queues.
+	 */
+	uint32_t non_cp_doorbells_start;
+	uint32_t non_cp_doorbells_end;
 
 	/* Base address of doorbell aperture. */
 	phys_addr_t doorbell_physical_address;