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Message-ID: <20240405115815.3226315-4-pbonzini@redhat.com>
Date: Fri, 5 Apr 2024 07:58:14 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
Tianrui Zhao <zhaotianrui@...ngson.cn>,
Bibo Mao <maobibo@...ngson.cn>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Nicholas Piggin <npiggin@...il.com>,
Anup Patel <anup@...infault.org>,
Atish Patra <atishp@...shpatra.org>,
Sean Christopherson <seanjc@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>,
linux-arm-kernel@...ts.infradead.org,
kvmarm@...ts.linux.dev,
loongarch@...ts.linux.dev,
linux-mips@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org,
kvm-riscv@...ts.infradead.org,
linux-mm@...ck.org,
linux-trace-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: [PATCH 3/4] mmu_notifier: remove the .change_pte() callback
The scope of set_pte_at_notify() has reduced more and more through the
years. Initially, it was meant for when the change to the PTE was
not bracketed by mmu_notifier_invalidate_range_{start,end}(). However,
that has not been so for over ten years. During all this period
the only implementation of .change_pte() was KVM and it
had no actual functionality, because it was called after
mmu_notifier_invalidate_range_start() zapped the secondary PTE.
Now that this (nonfunctional) user of the .change_pte() callback is
gone, the whole callback can be removed. For now, leave in place
set_pte_at_notify() even though it is just a synonym for set_pte_at().
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
include/linux/mmu_notifier.h | 46 ++----------------------------------
mm/mmu_notifier.c | 17 -------------
2 files changed, 2 insertions(+), 61 deletions(-)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index f349e08a9dfe..8c72bf651606 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -122,15 +122,6 @@ struct mmu_notifier_ops {
struct mm_struct *mm,
unsigned long address);
- /*
- * change_pte is called in cases that pte mapping to page is changed:
- * for example, when ksm remaps pte to point to a new shared page.
- */
- void (*change_pte)(struct mmu_notifier *subscription,
- struct mm_struct *mm,
- unsigned long address,
- pte_t pte);
-
/*
* invalidate_range_start() and invalidate_range_end() must be
* paired and are called only when the mmap_lock and/or the
@@ -392,8 +383,6 @@ extern int __mmu_notifier_clear_young(struct mm_struct *mm,
unsigned long end);
extern int __mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address);
-extern void __mmu_notifier_change_pte(struct mm_struct *mm,
- unsigned long address, pte_t pte);
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,
@@ -439,13 +428,6 @@ static inline int mmu_notifier_test_young(struct mm_struct *mm,
return 0;
}
-static inline void mmu_notifier_change_pte(struct mm_struct *mm,
- unsigned long address, pte_t pte)
-{
- if (mm_has_notifiers(mm))
- __mmu_notifier_change_pte(mm, address, pte);
-}
-
static inline void
mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
@@ -581,26 +563,6 @@ static inline void mmu_notifier_range_init_owner(
__young; \
})
-/*
- * set_pte_at_notify() sets the pte _after_ running the notifier.
- * This is safe to start by updating the secondary MMUs, because the primary MMU
- * pte invalidate must have already happened with a ptep_clear_flush() before
- * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is
- * required when we change both the protection of the mapping from read-only to
- * read-write and the pfn (like during copy on write page faults). Otherwise the
- * old page would remain mapped readonly in the secondary MMUs after the new
- * page is already writable by some CPU through the primary MMU.
- */
-#define set_pte_at_notify(__mm, __address, __ptep, __pte) \
-({ \
- struct mm_struct *___mm = __mm; \
- unsigned long ___address = __address; \
- pte_t ___pte = __pte; \
- \
- mmu_notifier_change_pte(___mm, ___address, ___pte); \
- set_pte_at(___mm, ___address, __ptep, ___pte); \
-})
-
#else /* CONFIG_MMU_NOTIFIER */
struct mmu_notifier_range {
@@ -650,11 +612,6 @@ static inline int mmu_notifier_test_young(struct mm_struct *mm,
return 0;
}
-static inline void mmu_notifier_change_pte(struct mm_struct *mm,
- unsigned long address, pte_t pte)
-{
-}
-
static inline void
mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
@@ -693,7 +650,6 @@ static inline void mmu_notifier_subscriptions_destroy(struct mm_struct *mm)
#define ptep_clear_flush_notify ptep_clear_flush
#define pmdp_huge_clear_flush_notify pmdp_huge_clear_flush
#define pudp_huge_clear_flush_notify pudp_huge_clear_flush
-#define set_pte_at_notify set_pte_at
static inline void mmu_notifier_synchronize(void)
{
@@ -701,4 +657,6 @@ static inline void mmu_notifier_synchronize(void)
#endif /* CONFIG_MMU_NOTIFIER */
+#define set_pte_at_notify set_pte_at
+
#endif /* _LINUX_MMU_NOTIFIER_H */
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index ec3b068cbbe6..8982e6139d07 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -424,23 +424,6 @@ int __mmu_notifier_test_young(struct mm_struct *mm,
return young;
}
-void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address,
- pte_t pte)
-{
- struct mmu_notifier *subscription;
- int id;
-
- id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(subscription,
- &mm->notifier_subscriptions->list, hlist,
- srcu_read_lock_held(&srcu)) {
- if (subscription->ops->change_pte)
- subscription->ops->change_pte(subscription, mm, address,
- pte);
- }
- srcu_read_unlock(&srcu, id);
-}
-
static int mn_itree_invalidate(struct mmu_notifier_subscriptions *subscriptions,
const struct mmu_notifier_range *range)
{
--
2.43.0
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