gru: check context state on reload

Check whether the gru state being loaded into a gru is from a new context
or a previously unloaded context.  If new, simply zero out the hardware
context; if unloaded and valid, reload the old state.

This change is primarily for reloading kernel contexts where the previous
is not required to be saved.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/sgi-gru/grumain.c

@@ -307,11 +307,12 @@ struct gru_thread_state *gru_alloc_gts(struct vm_area_struct *vma,
 
 	bytes = DSR_BYTES(dsr_au_count) + CBR_BYTES(cbr_au_count);
 	bytes += sizeof(struct gru_thread_state);
-	gts = kzalloc(bytes, GFP_KERNEL);
+	gts = kmalloc(bytes, GFP_KERNEL);
 	if (!gts)
 		return NULL;
 
 	STAT(gts_alloc);
+	memset(gts, 0, sizeof(struct gru_thread_state)); /* zero out header */
 	atomic_set(&gts->ts_refcnt, 1);
 	mutex_init(&gts->ts_ctxlock);
 	gts->ts_cbr_au_count = cbr_au_count;
@@ -458,7 +459,8 @@ static void gru_prefetch_context(void *gseg, void *cb, void *cbe,
 }
 
 static void gru_load_context_data(void *save, void *grubase, int ctxnum,
-				  unsigned long cbrmap, unsigned long dsrmap)
+				  unsigned long cbrmap, unsigned long dsrmap,
+				  int data_valid)
 {
 	void *gseg, *cb, *cbe;
 	unsigned long length;
@@ -471,12 +473,22 @@ static void gru_load_context_data(void *save, void *grubase, int ctxnum,
 	gru_prefetch_context(gseg, cb, cbe, cbrmap, length);
 
 	for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+		if (data_valid) {
 			save += gru_copy_handle(cb, save);
-		save += gru_copy_handle(cbe + i * GRU_HANDLE_STRIDE, save);
+			save += gru_copy_handle(cbe + i * GRU_HANDLE_STRIDE,
+						save);
+		} else {
+			memset(cb, 0, GRU_CACHE_LINE_BYTES);
+			memset(cbe + i * GRU_HANDLE_STRIDE, 0,
+						GRU_CACHE_LINE_BYTES);
+		}
 		cb += GRU_HANDLE_STRIDE;
 	}
 
+	if (data_valid)
 		memcpy(gseg + GRU_DS_BASE, save, length);
+	else
+		memset(gseg + GRU_DS_BASE, 0, length);
 }
 
 static void gru_unload_context_data(void *save, void *grubase, int ctxnum,
@@ -517,10 +529,12 @@ void gru_unload_context(struct gru_thread_state *gts, int savestate)
 
 	if (!is_kernel_context(gts))
 		gru_unload_mm_tracker(gru, gts);
-	if (savestate)
+	if (savestate) {
 		gru_unload_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr,
 					ctxnum, gts->ts_cbr_map,
 					gts->ts_dsr_map);
+		gts->ts_data_valid = 1;
+	}
 
 	if (cch_deallocate(cch))
 		BUG();
@@ -576,7 +590,7 @@ void gru_load_context(struct gru_thread_state *gts)
 	}
 
 	gru_load_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr, ctxnum,
-			      gts->ts_cbr_map, gts->ts_dsr_map);
+			gts->ts_cbr_map, gts->ts_dsr_map, gts->ts_data_valid);
 
 	if (cch_start(cch))
 		BUG();

drivers/misc/sgi-gru/grutables.h

@@ -385,6 +385,8 @@ struct gru_thread_state {
 						   after migration */
 	char			ts_cbr_idx[GRU_CBR_AU];/* CBR numbers of each
 							  allocated CB */
+	int			ts_data_valid;	/* Indicates if ts_gdata has
+						   valid data */
 	unsigned long		ts_gdata[0];	/* save area for GRU data (CB,
 						   DS, CBE) */
 };