Revert "Set guard page as disabled as default"

This reverts commit 65d680c035.

Change-Id: I09b7e7915ec4759cab57d5863089a2c4a44dfacd
Signed-off-by: Amber Lin <Amber.Lin@amd.com>

src/fmm.c

@@ -1432,7 +1432,7 @@ HSAKMT_STATUS fmm_init_process_apertures(unsigned int NumNodes)
 	uint32_t num_of_nodes;
 	HSAKMT_STATUS ret = HSAKMT_STATUS_SUCCESS;
 	char *disableCache, *pagedUserptr, *checkUserptr, *guardPagesStr;
-	unsigned int guardPages = 0;
+	unsigned int guardPages = 1;
 	struct pci_access *pacc;
 
 	/* If HSA_DISABLE_CACHE is set to a non-0 value, disable caching */
@@ -1452,10 +1452,10 @@ HSAKMT_STATUS fmm_init_process_apertures(unsigned int NumNodes)
 	checkUserptr = getenv("HSA_CHECK_USERPTR");
 	svm.check_userptr = (checkUserptr && strcmp(checkUserptr, "0"));
 
-	/* Specify number of guard pages for SVM apertures, default is 0 */
+	/* Specify number of guard pages for SVM apertures, default is 1 */
 	guardPagesStr = getenv("HSA_SVM_GUARD_PAGES");
 	if (!guardPagesStr || sscanf(guardPagesStr, "%u", &guardPages) != 1)
-		guardPages = 0;
+		guardPages = 1;
 
 	/* Trade off - NumNodes includes GPU nodes + CPU Node. So in
 	 * systems with CPU node, slightly more memory is allocated than