[RFC/PATCH 22/22] RFC: s390/mm: Add gmap lock classes

Janosch Frank
2017-11-06T22:41:55Z

A shadow gmap and its parent are locked right after each other when
doing VSIE management. Lockdep can't differentiate between the two
classes without some help.

TODO: Not sure yet if I have to annotate all and if gmap_pmd_walk will
be used by both shadow and parent

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
arch/s390/include/asm/gmap.h | 6 ++++++
arch/s390/mm/gmap.c | 40 ++++++++++++++++++++--------------------
2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index 15a7834..31fad98 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -19,6 +19,12 @@
#define _SEGMENT_ENTRY_GMAP_UC 0x4000 /* user dirty (migration) */
#define _SEGMENT_ENTRY_GMAP_VSIE 0x8000 /* vsie bit */

+
+enum gmap_lock_class {
+ GMAP_LOCK_PARENT,
+ GMAP_LOCK_SHADOW
+};
+
/**
* struct gmap_struct - guest address space
* @list: list head for the mm->context gmap list
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 3cc2765..b17f424 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -198,7 +198,7 @@ static void gmap_free(struct gmap *gmap)
gmap_radix_tree_free(&gmap->host_to_guest);

/* Free split pmd page tables */
- spin_lock(&gmap->guest_table_lock);
+ spin_lock_nested(&gmap->guest_table_lock, GMAP_LOCK_PARENT);
list_for_each_entry_safe(page, next, &gmap->split_list, lru)
page_table_free_pgste(page);
spin_unlock(&gmap->guest_table_lock);
@@ -1385,7 +1385,7 @@ static int gmap_protect_rmap_large(struct gmap *sg, struct gmap_rmap *rmap,
if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
return -EAGAIN;

- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
rc = gmap_protect_large(sg->parent, paddr, vmaddr, pmdp, hpmdp,
prot, GMAP_ENTRY_VSIE);
if (!rc)
@@ -1413,7 +1413,7 @@ static int gmap_protect_rmap_pte(struct gmap *sg, struct gmap_rmap *rmap,
ptep = pte_alloc_map_lock(sg->parent->mm, pmdp, paddr, &ptl);

if (ptep) {
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
rc = ptep_force_prot(sg->parent->mm, paddr, ptep, prot,
PGSTE_VSIE_BIT);
if (!rc)
@@ -1932,7 +1932,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
/* only allow one real-space gmap shadow */
list_for_each_entry(sg, &parent->children, list) {
if (sg->orig_asce & _ASCE_REAL_SPACE) {
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
gmap_unshadow(sg);
spin_unlock(&sg->guest_table_lock);
list_del(&sg->list);
@@ -2004,7 +2004,7 @@ int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_r2t = (unsigned long *) page_to_phys(page);
/* Install shadow region second table */
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
table = gmap_table_walk(sg, saddr, 4); /* get region-1 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
@@ -2037,7 +2037,7 @@ int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
offset = ((r2t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((r2t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (!rc) {
table = gmap_table_walk(sg, saddr, 4);
if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
@@ -2088,7 +2088,7 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_r3t = (unsigned long *) page_to_phys(page);
/* Install shadow region second table */
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
table = gmap_table_walk(sg, saddr, 3); /* get region-2 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
@@ -2120,7 +2120,7 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
offset = ((r3t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((r3t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (!rc) {
table = gmap_table_walk(sg, saddr, 3);
if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
@@ -2171,7 +2171,7 @@ int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_sgt = (unsigned long *) page_to_phys(page);
/* Install shadow region second table */
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
table = gmap_table_walk(sg, saddr, 2); /* get region-3 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
@@ -2204,7 +2204,7 @@ int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
offset = ((sgt & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((sgt & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (!rc) {
table = gmap_table_walk(sg, saddr, 2);
if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
@@ -2260,7 +2260,7 @@ int gmap_shadow_sgt_lookup(struct gmap *sg, unsigned long saddr,
int rc = -EAGAIN;

BUG_ON(!gmap_is_shadow(sg));
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (sg->asce & _ASCE_TYPE_MASK) {
/* >2 GB guest */
r3e = (unsigned long *) gmap_table_walk(sg, saddr, 2);
@@ -2327,7 +2327,7 @@ int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_pgt = (unsigned long *) page_to_phys(page);
/* Install shadow page table */
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
@@ -2355,7 +2355,7 @@ int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
raddr = (saddr & _SEGMENT_MASK) | _SHADOW_RMAP_SEGMENT;
origin = pgt & _SEGMENT_ENTRY_ORIGIN & PAGE_MASK;
rc = gmap_protect_rmap(sg, raddr, origin, PAGE_SIZE, PROT_READ);
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (!rc) {
table = gmap_table_walk(sg, saddr, 1);
if (!table || (*table & _SEGMENT_ENTRY_ORIGIN) !=
@@ -2417,7 +2417,7 @@ int gmap_shadow_segment(struct gmap *sg, unsigned long saddr, pmd_t pmd)
if (spmdp) {
if (!pmd_large(*spmdp))
BUG();
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
/* Get shadow segment table pointer */
tpmdp = (pmd_t *) gmap_table_walk(sg, saddr, 1);
if (!tpmdp) {
@@ -2513,7 +2513,7 @@ int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte)
rc = -EAGAIN;
spmdp = gmap_pmd_op_walk(parent, paddr);
if (spmdp && !(pmd_val(*spmdp) & _SEGMENT_ENTRY_INVALID)) {
- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
/* Get page table pointer */
tptep = (pte_t *) gmap_table_walk(sg, saddr, 0);
if (!tptep) {
@@ -2597,7 +2597,7 @@ static void gmap_shadow_notify_pmd(struct gmap *sg, unsigned long vmaddr,

BUG_ON(!gmap_is_shadow(sg));

- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (sg->removed) {
spin_unlock(&sg->guest_table_lock);
return;
@@ -2658,7 +2658,7 @@ static void gmap_shadow_notify(struct gmap *sg, unsigned long vmaddr,

BUG_ON(!gmap_is_shadow(sg));

- spin_lock(&sg->guest_table_lock);
+ spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
if (sg->removed) {
spin_unlock(&sg->guest_table_lock);
return;
@@ -2899,7 +2899,7 @@ static void gmap_pmdp_clear(struct mm_struct *mm, unsigned long vmaddr,

rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
- spin_lock(&gmap->guest_table_lock);
+ spin_lock_nested(&gmap->guest_table_lock, GMAP_LOCK_PARENT);
pmdp = (pmd_t *)radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (pmdp) {
@@ -2949,7 +2949,7 @@ void gmap_pmdp_idte_local(struct mm_struct *mm, unsigned long vmaddr)

rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
- spin_lock(&gmap->guest_table_lock);
+ spin_lock_nested(&gmap->guest_table_lock, GMAP_LOCK_PARENT);
entry = radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (entry) {
@@ -2984,7 +2984,7 @@ void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr)

rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
- spin_lock(&gmap->guest_table_lock);
+ spin_lock_nested(&gmap->guest_table_lock, GMAP_LOCK_PARENT);
entry = radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (entry) {
--
2.7.4