1 /* 2 * Copyright IBM Corp. 2008 3 * 4 * Guest page hinting for unused pages. 5 * 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/errno.h> 11 #include <linux/types.h> 12 #include <linux/mm.h> 13 #include <linux/gfp.h> 14 #include <linux/init.h> 15 16 #define ESSA_SET_STABLE 1 17 #define ESSA_SET_UNUSED 2 18 19 static int cmma_flag = 1; 20 21 static int __init cmma(char *str) 22 { 23 char *parm; 24 25 parm = strstrip(str); 26 if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) { 27 cmma_flag = 1; 28 return 1; 29 } 30 cmma_flag = 0; 31 if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0) 32 return 1; 33 return 0; 34 } 35 __setup("cmma=", cmma); 36 37 static inline int cmma_test_essa(void) 38 { 39 register unsigned long tmp asm("0") = 0; 40 register int rc asm("1") = -EOPNOTSUPP; 41 42 asm volatile( 43 " .insn rrf,0xb9ab0000,%1,%1,0,0\n" 44 "0: la %0,0\n" 45 "1:\n" 46 EX_TABLE(0b,1b) 47 : "+&d" (rc), "+&d" (tmp)); 48 return rc; 49 } 50 51 void __init cmma_init(void) 52 { 53 if (!cmma_flag) 54 return; 55 if (cmma_test_essa()) 56 cmma_flag = 0; 57 } 58 59 static inline void set_page_unstable(struct page *page, int order) 60 { 61 int i, rc; 62 63 for (i = 0; i < (1 << order); i++) 64 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0" 65 : "=&d" (rc) 66 : "a" (page_to_phys(page + i)), 67 "i" (ESSA_SET_UNUSED)); 68 } 69 70 void arch_free_page(struct page *page, int order) 71 { 72 if (!cmma_flag) 73 return; 74 set_page_unstable(page, order); 75 } 76 77 static inline void set_page_stable(struct page *page, int order) 78 { 79 int i, rc; 80 81 for (i = 0; i < (1 << order); i++) 82 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0" 83 : "=&d" (rc) 84 : "a" (page_to_phys(page + i)), 85 "i" (ESSA_SET_STABLE)); 86 } 87 88 void arch_alloc_page(struct page *page, int order) 89 { 90 if (!cmma_flag) 91 return; 92 set_page_stable(page, order); 93 } 94 95 void arch_set_page_states(int make_stable) 96 { 97 unsigned long flags, order, t; 98 struct list_head *l; 99 struct page *page; 100 struct zone *zone; 101 102 if (!cmma_flag) 103 return; 104 if (make_stable) 105 drain_local_pages(NULL); 106 for_each_populated_zone(zone) { 107 spin_lock_irqsave(&zone->lock, flags); 108 for_each_migratetype_order(order, t) { 109 list_for_each(l, &zone->free_area[order].free_list[t]) { 110 page = list_entry(l, struct page, lru); 111 if (make_stable) 112 set_page_stable(page, order); 113 else 114 set_page_unstable(page, order); 115 } 116 } 117 spin_unlock_irqrestore(&zone->lock, flags); 118 } 119 } 120