drm/amdkfd: Separate doorbell allocation from PASID

PASID management is moving into KGD. Limiting the PASID range to the
number of doorbell pages is no longer practical.

Signed-off-by: Felix Kuehling <[e-mail]>
Acked-by: Alex Deucher <[e-mail]>
Reviewed-by: Oded Gabbay <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 	pasid_limit = min_t(unsigned int,
 			(unsigned int)(1 << kfd->device_info->max_pasid_bits),
 			iommu_info.max_pasids);
-	/*
-	 * last pasid is used for kernel queues doorbells
-	 * in the future the last pasid might be used for a kernel thread.
-	 */
-	pasid_limit = min_t(unsigned int,
-				pasid_limit,
-				kfd->doorbell_process_limit - 1);
 
 	err = amd_iommu_init_device(kfd->pdev, pasid_limit);
 	if (err < 0) {

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

···
 #include <linux/mman.h>
 #include <linux/slab.h>
 #include <linux/io.h>
+#include <linux/idr.h>
 
 /*
- * This extension supports a kernel level doorbells management for
- * the kernel queues.
- * Basically the last doorbells page is devoted to kernel queues
- * and that's assures that any user process won't get access to the
- * kernel doorbells page
+ * This extension supports a kernel level doorbells management for the
+ * kernel queues using the first doorbell page reserved for the kernel.
  */
 
-#define KERNEL_DOORBELL_PASID 1
+static DEFINE_IDA(doorbell_ida);
+static unsigned int max_doorbell_slices;
 #define KFD_SIZE_OF_DOORBELL_IN_BYTES 4
 
 /*
···
 			(doorbell_aperture_size - doorbell_start_offset) /
 						doorbell_process_allocation();
 	else
-		doorbell_process_limit = 0;
+		return -ENOSPC;
+
+	if (!max_doorbell_slices ||
+	    doorbell_process_limit < max_doorbell_slices)
+		max_doorbell_slices = doorbell_process_limit;
 
 	kfd->doorbell_base = kfd->shared_resources.doorbell_physical_address +
 				doorbell_start_offset;
 
 	kfd->doorbell_id_offset = doorbell_start_offset / sizeof(u32);
-	kfd->doorbell_process_limit = doorbell_process_limit - 1;
 
 	kfd->doorbell_kernel_ptr = ioremap(kfd->doorbell_base,
 						doorbell_process_allocation());
···
 		return NULL;
 
 	/*
-	 * Calculating the kernel doorbell offset using "faked" kernel
-	 * pasid that allocated for kernel queues only
+	 * Calculating the kernel doorbell offset using the first
+	 * doorbell page.
 	 */
-	*doorbell_off = KERNEL_DOORBELL_PASID * (doorbell_process_allocation() /
-							sizeof(u32)) + inx;
+	*doorbell_off = kfd->doorbell_id_offset + inx;
 
 	pr_debug("Get kernel queue doorbell\n"
 			 "     doorbell offset   == 0x%08X\n"
···
 {
 	/*
 	 * doorbell_id_offset accounts for doorbells taken by KGD.
-	 * pasid * doorbell_process_allocation/sizeof(u32) adjusts
-	 * to the process's doorbells
+	 * index * doorbell_process_allocation/sizeof(u32) adjusts to
+	 * the process's doorbells.
 	 */
 	return kfd->doorbell_id_offset +
-		process->pasid * (doorbell_process_allocation()/sizeof(u32)) +
+		process->doorbell_index
+		* doorbell_process_allocation() / sizeof(u32) +
 		queue_id;
 }
 
···
 					struct kfd_process *process)
 {
 	return dev->doorbell_base +
-		process->pasid * doorbell_process_allocation();
+		process->doorbell_index * doorbell_process_allocation();
+}
+
+int kfd_alloc_process_doorbells(struct kfd_process *process)
+{
+	int r = ida_simple_get(&doorbell_ida, 1, max_doorbell_slices,
+				GFP_KERNEL);
+	if (r > 0)
+		process->doorbell_index = r;
+
+	return r;
+}
+
+void kfd_free_process_doorbells(struct kfd_process *process)
+{
+	if (process->doorbell_index)
+		ida_simple_remove(&doorbell_ida, process->doorbell_index);
 }

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

···
 					 * to HW doorbell, GFX reserved some
 					 * at the start)
 					 */
-	size_t doorbell_process_limit;	/* Number of processes we have doorbell
-					 * space for.
-					 */
 	u32 __iomem *doorbell_kernel_ptr; /* This is a pointer for a doorbells
 					   * page used by kernel queue
 					   */
···
 	struct rcu_head	rcu;
 
 	unsigned int pasid;
+	unsigned int doorbell_index;
 
 	/*
 	 * List of kfd_process_device structures,
···
 unsigned int kfd_queue_id_to_doorbell(struct kfd_dev *kfd,
 					struct kfd_process *process,
 					unsigned int queue_id);
+phys_addr_t kfd_get_process_doorbells(struct kfd_dev *dev,
+					struct kfd_process *process);
+int kfd_alloc_process_doorbells(struct kfd_process *process);
+void kfd_free_process_doorbells(struct kfd_process *process);
 
 /* GTT Sub-Allocator */
 
···
 void pm_release_ib(struct packet_manager *pm);
 
 uint64_t kfd_get_number_elems(struct kfd_dev *kfd);
-phys_addr_t kfd_get_process_doorbells(struct kfd_dev *dev,
-					struct kfd_process *process);
 
 /* Events */
 extern const struct kfd_event_interrupt_class event_interrupt_class_cik;

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

···
 	kfd_event_free_process(p);
 
 	kfd_pasid_free(p->pasid);
+	kfd_free_process_doorbells(p);
 
 	mutex_unlock(&p->mutex);
 
···
 	if (process->pasid == 0)
 		goto err_alloc_pasid;
 
+	if (kfd_alloc_process_doorbells(process) < 0)
+		goto err_alloc_doorbells;
+
 	mutex_init(&process->mutex);
 
 	process->mm = thread->mm;
···
 	mmu_notifier_unregister_no_release(&process->mmu_notifier, process->mm);
 err_mmu_notifier:
 	mutex_destroy(&process->mutex);
+	kfd_free_process_doorbells(process);
+err_alloc_doorbells:
 	kfd_pasid_free(process->pasid);
 err_alloc_pasid:
 	kfree(process->queues);