[PATCH v4 04/12] drm/xe: Add xe_device_asid_to_vm helper

[Matthew Brost <matthew.brost@intel.com>]

Introduce the xe_device_asid_to_vm helper, which can be used throughout
the driver to resolve the VM from a given ASID.

v4:
 - Move forward declare after includes (Stuart)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
---
 drivers/gpu/drm/xe/xe_device.c | 25 +++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_device.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index e400ad5c9f9e..445cf6da9dc7 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -1417,3 +1417,28 @@ const char *xe_wedged_mode_to_string(enum xe_wedged_mode mode)
 		return "<invalid>";
 	}
 }
+
+/**
+ * xe_device_asid_to_vm() - Find VM from ASID
+ * @xe: the &xe_device
+ * @asid: Address space ID
+ *
+ * Find a VM from ASID and take a reference to VM which caller must drop.
+ * Reclaim safe.
+ *
+ * Return: VM on success, ERR_PTR on failure
+ */
+struct xe_vm *xe_device_asid_to_vm(struct xe_device *xe, u32 asid)
+{
+	struct xe_vm *vm;
+
+	down_read(&xe->usm.lock);
+	vm = xa_load(&xe->usm.asid_to_vm, asid);
+	if (vm)
+		xe_vm_get(vm);
+	else
+		vm = ERR_PTR(-EINVAL);
+	up_read(&xe->usm.lock);
+
+	return vm;
+}
diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
index 3740143790db..d25421e5181c 100644
--- a/drivers/gpu/drm/xe/xe_device.h
+++ b/drivers/gpu/drm/xe/xe_device.h
@@ -12,6 +12,8 @@
 #include "xe_gt_types.h"
 #include "xe_sriov.h"
 
+struct xe_vm;
+
 static inline struct xe_device *to_xe_device(const struct drm_device *dev)
 {
 	return container_of(dev, struct xe_device, drm);
@@ -204,6 +206,8 @@ int xe_is_injection_active(void);
 
 bool xe_is_xe_file(const struct file *file);
 
+struct xe_vm *xe_device_asid_to_vm(struct xe_device *xe, u32 asid);
+
 /*
  * Occasionally it is seen that the G2H worker starts running after a delay of more than
  * a second even after being queued and activated by the Linux workqueue subsystem. This
-- 
2.34.1