mmu_notifiers: rename invalidate_range notifier

There are two main use cases for mmu notifiers.  One is by KVM which uses
mmu_notifier_invalidate_range_start()/end() to manage a software TLB.

The other is to manage hardware TLBs which need to use the
invalidate_range() callback because HW can establish new TLB entries at
any time.  Hence using start/end() can lead to memory corruption as these
callbacks happen too soon/late during page unmap.

mmu notifier users should therefore either use the start()/end() callbacks
or the invalidate_range() callbacks.  To make this usage clearer rename
the invalidate_range() callback to arch_invalidate_secondary_tlbs() and
update documention.

Link: https://lkml.kernel.org/r/6f77248cd25545c8020a54b4e567e8b72be4dca1.1690292440.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Andrew Donnellan <ajd@linux.ibm.com>
Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Cc: Frederic Barrat <fbarrat@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zhi Wang <zhi.wang.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 24 insertions, 24 deletions

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index f2e9edc6aa43..6e3c857606f1 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -187,27 +187,27 @@ struct mmu_notifier_ops {
 				     const struct mmu_notifier_range *range);
 
 	/*
-	 * invalidate_range() is either called between
-	 * invalidate_range_start() and invalidate_range_end() when the
-	 * VM has to free pages that where unmapped, but before the
-	 * pages are actually freed, or outside of _start()/_end() when
-	 * a (remote) TLB is necessary.
+	 * arch_invalidate_secondary_tlbs() is used to manage a non-CPU TLB
+	 * which shares page-tables with the CPU. The
+	 * invalidate_range_start()/end() callbacks should not be implemented as
+	 * invalidate_secondary_tlbs() already catches the points in time when
+	 * an external TLB needs to be flushed.
 	 *
-	 * If invalidate_range() is used to manage a non-CPU TLB with
-	 * shared page-tables, it not necessary to implement the
-	 * invalidate_range_start()/end() notifiers, as
-	 * invalidate_range() already catches the points in time when an
-	 * external TLB range needs to be flushed. For more in depth
-	 * discussion on this see Documentation/mm/mmu_notifier.rst
+	 * This requires arch_invalidate_secondary_tlbs() to be called while
+	 * holding the ptl spin-lock and therefore this callback is not allowed
+	 * to sleep.
 	 *
-	 * Note that this function might be called with just a sub-range
-	 * of what was passed to invalidate_range_start()/end(), if
-	 * called between those functions.
+	 * This is called by architecture code whenever invalidating a TLB
+	 * entry. It is assumed that any secondary TLB has the same rules for
+	 * when invalidations are required. If this is not the case architecture
+	 * code will need to call this explicitly when required for secondary
+	 * TLB invalidation.
 	 */
-	void (*invalidate_range)(struct mmu_notifier *subscription,
-				 struct mm_struct *mm,
-				 unsigned long start,
-				 unsigned long end);
+	void (*arch_invalidate_secondary_tlbs)(
+					struct mmu_notifier *subscription,
+					struct mm_struct *mm,
+					unsigned long start,
+					unsigned long end);
 
 	/*
 	 * These callbacks are used with the get/put interface to manage the
@@ -396,8 +396,8 @@ 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_invalidate_range(struct mm_struct *mm,
-				  unsigned long start, unsigned long end);
+extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
+					unsigned long start, unsigned long end);
 extern bool
 mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *range);
 
@@ -483,11 +483,11 @@ mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 		__mmu_notifier_invalidate_range_end(range);
 }
 
-static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
-				  unsigned long start, unsigned long end)
+static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	if (mm_has_notifiers(mm))
-		__mmu_notifier_invalidate_range(mm, start, end);
+		__mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 static inline void mmu_notifier_subscriptions_init(struct mm_struct *mm)
@@ -664,7 +664,7 @@ void mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 {
 }
 
-static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
+static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
 				  unsigned long start, unsigned long end)
 {
 }