drm/amdkfd: start using tlb_seq from the VM subsystem

Instead of trying to figure out if a TLB flush is necessary or not use
the information provided by the VM subsystem now.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Philip Yang<Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -705,6 +705,7 @@ struct kfd_process_device {
 	/* VM context for GPUVM allocations */
 	struct file *drm_file;
 	void *drm_priv;
+	uint64_t tlb_seq;
 
 	/* GPUVM allocations storage */
 	struct idr alloc_idr;

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

@@ -1560,6 +1560,7 @@ int kfd_process_device_init_vm(struct kfd_process_device *pdd,
 		return ret;
 	}
 	pdd->drm_priv = drm_file->private_data;
+	pdd->tlb_seq = 0;
 
 	ret = kfd_process_device_reserve_ib_mem(pdd);
 	if (ret)
@@ -1949,8 +1950,14 @@ int kfd_reserved_mem_mmap(struct kfd_dev *dev, struct kfd_process *process,
 
 void kfd_flush_tlb(struct kfd_process_device *pdd, enum TLB_FLUSH_TYPE type)
 {
+	struct amdgpu_vm *vm = drm_priv_to_vm(pdd->drm_priv);
+	uint64_t tlb_seq = amdgpu_vm_tlb_seq(vm);
 	struct kfd_dev *dev = pdd->dev;
 
+	if (pdd->tlb_seq == tlb_seq)
+		return;
+
+	pdd->tlb_seq = tlb_seq;
 	if (dev->dqm->sched_policy == KFD_SCHED_POLICY_NO_HWS) {
 		/* Nothing to flush until a VMID is assigned, which
 		 * only happens when the first queue is created.