drm/amdgpu: Add PASID management

Allows assigning a PASID to a VM for identifying VMs involved in page
faults. The global PASID manager is also exported in the KFD
interface so that AMDGPU and KFD can share the PASID space.

PASIDs of different sizes can be requested. On APUs, the PASID size
is deterined by the capabilities of the IOMMU. So KFD must be able
to allocate PASIDs in a smaller range.

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/amdgpu/amdgpu_amdkfd_gfx_v7.c

···
 	.get_vmem_size = get_vmem_size,
 	.get_gpu_clock_counter = get_gpu_clock_counter,
 	.get_max_engine_clock_in_mhz = get_max_engine_clock_in_mhz,
+	.alloc_pasid = amdgpu_vm_alloc_pasid,
+	.free_pasid = amdgpu_vm_free_pasid,
 	.program_sh_mem_settings = kgd_program_sh_mem_settings,
 	.set_pasid_vmid_mapping = kgd_set_pasid_vmid_mapping,
 	.init_pipeline = kgd_init_pipeline,

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v8.c

···
 	.get_vmem_size = get_vmem_size,
 	.get_gpu_clock_counter = get_gpu_clock_counter,
 	.get_max_engine_clock_in_mhz = get_max_engine_clock_in_mhz,
+	.alloc_pasid = amdgpu_vm_alloc_pasid,
+	.free_pasid = amdgpu_vm_free_pasid,
 	.program_sh_mem_settings = kgd_program_sh_mem_settings,
 	.set_pasid_vmid_mapping = kgd_set_pasid_vmid_mapping,
 	.init_pipeline = kgd_init_pipeline,

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

···
 	}
 
 	r = amdgpu_vm_init(adev, &fpriv->vm,
-			   AMDGPU_VM_CONTEXT_GFX);
+			   AMDGPU_VM_CONTEXT_GFX, 0);
 	if (r) {
 		kfree(fpriv);
 		goto out_suspend;

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

···
  */
 #include <linux/dma-fence-array.h>
 #include <linux/interval_tree_generic.h>
+#include <linux/idr.h>
 #include <drm/drmP.h>
 #include <drm/amdgpu_drm.h>
 #include "amdgpu.h"
 #include "amdgpu_trace.h"
+
+/*
+ * PASID manager
+ *
+ * PASIDs are global address space identifiers that can be shared
+ * between the GPU, an IOMMU and the driver. VMs on different devices
+ * may use the same PASID if they share the same address
+ * space. Therefore PASIDs are allocated using a global IDA. VMs are
+ * looked up from the PASID per amdgpu_device.
+ */
+static DEFINE_IDA(amdgpu_vm_pasid_ida);
+
+/**
+ * amdgpu_vm_alloc_pasid - Allocate a PASID
+ * @bits: Maximum width of the PASID in bits, must be at least 1
+ *
+ * Allocates a PASID of the given width while keeping smaller PASIDs
+ * available if possible.
+ *
+ * Returns a positive integer on success. Returns %-EINVAL if bits==0.
+ * Returns %-ENOSPC if no PASID was available. Returns %-ENOMEM on
+ * memory allocation failure.
+ */
+int amdgpu_vm_alloc_pasid(unsigned int bits)
+{
+	int pasid = -EINVAL;
+
+	for (bits = min(bits, 31U); bits > 0; bits--) {
+		pasid = ida_simple_get(&amdgpu_vm_pasid_ida,
+				       1U << (bits - 1), 1U << bits,
+				       GFP_KERNEL);
+		if (pasid != -ENOSPC)
+			break;
+	}
+
+	return pasid;
+}
+
+/**
+ * amdgpu_vm_free_pasid - Free a PASID
+ * @pasid: PASID to free
+ */
+void amdgpu_vm_free_pasid(unsigned int pasid)
+{
+	ida_simple_remove(&amdgpu_vm_pasid_ida, pasid);
+}
 
 /*
  * GPUVM
···
  * Init @vm fields.
  */
 int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
-		   int vm_context)
+		   int vm_context, unsigned int pasid)
 {
 	const unsigned align = min(AMDGPU_VM_PTB_ALIGN_SIZE,
 		AMDGPU_VM_PTE_COUNT(adev) * 8);
···
 			goto error_free_root;
 	}
 
+	if (pasid) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&adev->vm_manager.pasid_lock, flags);
+		r = idr_alloc(&adev->vm_manager.pasid_idr, vm, pasid, pasid + 1,
+			      GFP_ATOMIC);
+		spin_unlock_irqrestore(&adev->vm_manager.pasid_lock, flags);
+		if (r < 0)
+			goto error_free_root;
+
+		vm->pasid = pasid;
+	}
+
 	return 0;
 
 error_free_root:
···
 	struct amdgpu_bo_va_mapping *mapping, *tmp;
 	bool prt_fini_needed = !!adev->gart.gart_funcs->set_prt;
 	int i;
+
+	if (vm->pasid) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&adev->vm_manager.pasid_lock, flags);
+		idr_remove(&adev->vm_manager.pasid_idr, vm->pasid);
+		spin_unlock_irqrestore(&adev->vm_manager.pasid_lock, flags);
+	}
 
 	amd_sched_entity_fini(vm->entity.sched, &vm->entity);
 
···
 	adev->vm_manager.vm_update_mode = 0;
 #endif
 
+	idr_init(&adev->vm_manager.pasid_idr);
+	spin_lock_init(&adev->vm_manager.pasid_lock);
 }
 
 /**
···
 void amdgpu_vm_manager_fini(struct amdgpu_device *adev)
 {
 	unsigned i, j;
+
+	WARN_ON(!idr_is_empty(&adev->vm_manager.pasid_idr));
+	idr_destroy(&adev->vm_manager.pasid_idr);
 
 	for (i = 0; i < AMDGPU_MAX_VMHUBS; ++i) {
 		struct amdgpu_vm_id_manager *id_mgr =

drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h

···
 #define __AMDGPU_VM_H__
 
 #include <linux/rbtree.h>
+#include <linux/idr.h>
 
 #include "gpu_scheduler.h"
 #include "amdgpu_sync.h"
···
 	/* Scheduler entity for page table updates */
 	struct amd_sched_entity	entity;
 
-	/* client id */
+	/* client id and PASID (TODO: replace client_id with PASID) */
 	u64                     client_id;
+	unsigned int		pasid;
 	/* dedicated to vm */
 	struct amdgpu_vm_id	*reserved_vmid[AMDGPU_MAX_VMHUBS];
 
···
 	 * BIT1[= 0] Compute updated by SDMA [= 1] by CPU
 	 */
 	int					vm_update_mode;
+
+	/* PASID to VM mapping, will be used in interrupt context to
+	 * look up VM of a page fault
+	 */
+	struct idr				pasid_idr;
+	spinlock_t				pasid_lock;
 };
 
+int amdgpu_vm_alloc_pasid(unsigned int bits);
+void amdgpu_vm_free_pasid(unsigned int pasid);
 void amdgpu_vm_manager_init(struct amdgpu_device *adev);
 void amdgpu_vm_manager_fini(struct amdgpu_device *adev);
 int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
-		   int vm_context);
+		   int vm_context, unsigned int pasid);
 void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm);
 void amdgpu_vm_get_pd_bo(struct amdgpu_vm *vm,
 			 struct list_head *validated,

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

···
  *
  * @get_max_engine_clock_in_mhz: Retrieves maximum GPU clock in MHz
  *
+ * @alloc_pasid: Allocate a PASID
+ * @free_pasid: Free a PASID
+ *
  * @program_sh_mem_settings: A function that should initiate the memory
  * properties such as main aperture memory type (cache / non cached) and
  * secondary aperture base address, size and memory type.
···
 	uint64_t (*get_gpu_clock_counter)(struct kgd_dev *kgd);
 
 	uint32_t (*get_max_engine_clock_in_mhz)(struct kgd_dev *kgd);
+
+	int (*alloc_pasid)(unsigned int bits);
+	void (*free_pasid)(unsigned int pasid);
 
 	/* Register access functions */
 	void (*program_sh_mem_settings)(struct kgd_dev *kgd, uint32_t vmid,