drm/amdkfd: Simplify events page allocator

The first event page is always big enough to handle all events.
Handling of multiple events pages is not supported by user mode, and
not necessary.
Signed-off-by: Yong Zhao <yong.zhao@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

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

@@ -60,7 +60,6 @@ struct kfd_event {
 	wait_queue_head_t wq; /* List of event waiters. */
 
 	/* Only for signal events. */
-	struct signal_page *signal_page;
 	unsigned int signal_slot_index;
 	uint64_t __user *user_signal_address;
 

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

@@ -540,8 +540,8 @@ struct kfd_process {
 	struct mutex event_mutex;
 	/* All events in process hashed by ID, linked on kfd_event.events. */
 	DECLARE_HASHTABLE(events, 4);
-	/* struct slot_page_header.event_pages */
-	struct list_head signal_event_pages;
+	/* Event page */
+	struct kfd_signal_page *signal_page;
 	u32 next_nonsignal_event_id;
 	size_t signal_event_count;
 	bool signal_event_limit_reached;