For implementers, the fast_only bool indicates that the age information
needs to be harvested such that we do not slow down other MMU operations,
and ideally that we are not ourselves slowed down by other MMU
operations. Usually this means that the implementation should be
lockless.
Also add mmu_notifier_test_young_fast_only() and
mmu_notifier_clear_young_fast_only() helpers to set fast_only for these
notifiers.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
include/linux/mmu_notifier.h | 46 +++++++++++++++++++++++++++++++-----
include/trace/events/kvm.h | 19 +++++++++------
mm/mmu_notifier.c | 12 ++++++----
virt/kvm/kvm_main.c | 12 ++++++----
4 files changed, 67 insertions(+), 22 deletions(-)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index e2dd57ca368b..45c5995ebd84 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -110,7 +110,8 @@ struct mmu_notifier_ops {
int (*clear_young)(struct mmu_notifier *subscription,
struct mm_struct *mm,
unsigned long start,
- unsigned long end);
+ unsigned long end,
+ bool fast_only);
/*
* test_young is called to check the young/accessed bitflag in
@@ -120,7 +121,8 @@ struct mmu_notifier_ops {
*/
int (*test_young)(struct mmu_notifier *subscription,
struct mm_struct *mm,
- unsigned long address);
+ unsigned long address,
+ bool fast_only);
/*
* invalidate_range_start() and invalidate_range_end() must be
@@ -380,9 +382,11 @@ extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
unsigned long end);
extern int __mmu_notifier_clear_young(struct mm_struct *mm,
unsigned long start,
- unsigned long end);
+ unsigned long end,
+ bool fast_only);
extern int __mmu_notifier_test_young(struct mm_struct *mm,
- unsigned long address);
+ unsigned long address,
+ bool fast_only);
extern int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *r);
extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r);
extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
@@ -416,7 +420,16 @@ static inline int mmu_notifier_clear_young(struct mm_struct *mm,
unsigned long end)
{
if (mm_has_notifiers(mm))
- return __mmu_notifier_clear_young(mm, start, end);
+ return __mmu_notifier_clear_young(mm, start, end, false);
+ return 0;
+}
+
+static inline int mmu_notifier_clear_young_fast_only(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ if (mm_has_notifiers(mm))
+ return __mmu_notifier_clear_young(mm, start, end, true);
return 0;
}
@@ -424,7 +437,15 @@ static inline int mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address)
{
if (mm_has_notifiers(mm))
- return __mmu_notifier_test_young(mm, address);
+ return __mmu_notifier_test_young(mm, address, false);
+ return 0;
+}
+
+static inline int mmu_notifier_test_young_fast_only(struct mm_struct *mm,
+ unsigned long address)
+{
+ if (mm_has_notifiers(mm))
+ return __mmu_notifier_test_young(mm, address, true);
return 0;
}
@@ -613,12 +634,25 @@ static inline int mmu_notifier_clear_young(struct mm_struct *mm,
return 0;
}
+static inline int mmu_notifier_clear_young_fast_only(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ return 0;
+}
+
static inline int mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address)
{
return 0;
}
+static inline int mmu_notifier_test_young_fast_only(struct mm_struct *mm,
+ unsigned long address)
+{
+ return 0;
+}
+
static inline void
mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index 74e40d5d4af4..6d9485cf3e51 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -457,36 +457,41 @@ TRACE_EVENT(kvm_unmap_hva_range,
);
TRACE_EVENT(kvm_age_hva,
- TP_PROTO(unsigned long start, unsigned long end),
- TP_ARGS(start, end),
+ TP_PROTO(unsigned long start, unsigned long end, bool fast_only),
+ TP_ARGS(start, end, fast_only),
TP_STRUCT__entry(
__field( unsigned long, start )
__field( unsigned long, end )
+ __field( bool, fast_only )
),
TP_fast_assign(
__entry->start = start;
__entry->end = end;
+ __entry->fast_only = fast_only;
),
- TP_printk("mmu notifier age hva: %#016lx -- %#016lx",
- __entry->start, __entry->end)
+ TP_printk("mmu notifier age hva: %#016lx -- %#016lx fast_only: %d",
+ __entry->start, __entry->end, __entry->fast_only)
);
TRACE_EVENT(kvm_test_age_hva,
- TP_PROTO(unsigned long hva),
- TP_ARGS(hva),
+ TP_PROTO(unsigned long hva, bool fast_only),
+ TP_ARGS(hva, fast_only),
TP_STRUCT__entry(
__field( unsigned long, hva )
+ __field( bool, fast_only )
),
TP_fast_assign(
__entry->hva = hva;
+ __entry->fast_only = fast_only;
),
- TP_printk("mmu notifier test age hva: %#016lx", __entry->hva)
+ TP_printk("mmu notifier test age hva: %#016lx fast_only: %d",
+ __entry->hva, __entry->fast_only)
);
#endif /* _TRACE_KVM_MAIN_H */
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 8982e6139d07..f9a0ca6ffe65 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -384,7 +384,8 @@ int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
int __mmu_notifier_clear_young(struct mm_struct *mm,
unsigned long start,
- unsigned long end)
+ unsigned long end,
+ bool fast_only)
{
struct mmu_notifier *subscription;
int young = 0, id;
@@ -395,7 +396,8 @@ int __mmu_notifier_clear_young(struct mm_struct *mm,
srcu_read_lock_held(&srcu)) {
if (subscription->ops->clear_young)
young |= subscription->ops->clear_young(subscription,
- mm, start, end);
+ mm, start, end,
+ fast_only);
}
srcu_read_unlock(&srcu, id);
@@ -403,7 +405,8 @@ int __mmu_notifier_clear_young(struct mm_struct *mm,
}
int __mmu_notifier_test_young(struct mm_struct *mm,
- unsigned long address)
+ unsigned long address,
+ bool fast_only)
{
struct mmu_notifier *subscription;
int young = 0, id;
@@ -414,7 +417,8 @@ int __mmu_notifier_test_young(struct mm_struct *mm,
srcu_read_lock_held(&srcu)) {
if (subscription->ops->test_young) {
young = subscription->ops->test_young(subscription, mm,
- address);
+ address,
+ fast_only);
if (young)
break;
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 33f8997a5c29..959b6d5d8ce4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -874,7 +874,7 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
unsigned long start,
unsigned long end)
{
- trace_kvm_age_hva(start, end);
+ trace_kvm_age_hva(start, end, false);
return kvm_handle_hva_range(mn, start, end, kvm_age_gfn);
}
@@ -882,9 +882,10 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
- unsigned long end)
+ unsigned long end,
+ bool fast_only)
{
- trace_kvm_age_hva(start, end);
+ trace_kvm_age_hva(start, end, fast_only);
/*
* Even though we do not flush TLB, this will still adversely
@@ -904,9 +905,10 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
struct mm_struct *mm,
- unsigned long address)
+ unsigned long address,
+ bool fast_only)
{
- trace_kvm_test_age_hva(address);
+ trace_kvm_test_age_hva(address, fast_only);
return kvm_handle_hva_range_no_flush(mn, address, address + 1,
kvm_test_age_gfn);
--
2.46.0.rc1.232.g9752f9e123-goog
