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 <Felix.Kuehling@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 74 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 2196bca7331c..9b795915cab1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -27,12 +27,59 @@
  */
 #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
  * GPUVM is similar to the legacy gart on older asics, however
  * rather than there being a single global gart table
@@ -2539,7 +2586,7 @@ void amdgpu_vm_adjust_size(struct amdgpu_device *adev, uint64_t vm_size, uint32_
  * 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);
@@ -2620,6 +2667,19 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 			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:
@@ -2673,6 +2733,14 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 	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);
 
 	if (!RB_EMPTY_ROOT(&vm->va)) {
@@ -2752,6 +2820,8 @@ void amdgpu_vm_manager_init(struct amdgpu_device *adev)
 	adev->vm_manager.vm_update_mode = 0;
 #endif
 
+	idr_init(&adev->vm_manager.pasid_idr);
+	spin_lock_init(&adev->vm_manager.pasid_lock);
 }
 
 /**
@@ -2765,6 +2835,9 @@ 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 =
 			&adev->vm_manager.id_mgr[i];