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>

arch/arm64/include/asm/tlbflush.h

@@ -253,7 +253,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
 	__tlbi(aside1is, asid);
 	__tlbi_user(aside1is, asid);
 	dsb(ish);
-	mmu_notifier_invalidate_range(mm, 0, -1UL);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 
 static inline void __flush_tlb_page_nosync(struct mm_struct *mm,
@@ -265,7 +265,7 @@ static inline void __flush_tlb_page_nosync(struct mm_struct *mm,
 	addr = __TLBI_VADDR(uaddr, ASID(mm));
 	__tlbi(vale1is, addr);
 	__tlbi_user(vale1is, addr);
-	mmu_notifier_invalidate_range(mm, uaddr & PAGE_MASK,
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, uaddr & PAGE_MASK,
 						(uaddr & PAGE_MASK) + PAGE_SIZE);
 }
 
@@ -400,7 +400,7 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
 		scale++;
 	}
 	dsb(ish);
-	mmu_notifier_invalidate_range(vma->vm_mm, start, end);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
 }
 
 static inline void flush_tlb_range(struct vm_area_struct *vma,

arch/powerpc/mm/book3s64/radix_hugetlbpage.c

@@ -39,7 +39,7 @@ void radix__flush_hugetlb_tlb_range(struct vm_area_struct *vma, unsigned long st
 		radix__flush_tlb_pwc_range_psize(vma->vm_mm, start, end, psize);
 	else
 		radix__flush_tlb_range_psize(vma->vm_mm, start, end, psize);
-	mmu_notifier_invalidate_range(vma->vm_mm, start, end);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
 }
 
 void radix__huge_ptep_modify_prot_commit(struct vm_area_struct *vma,

arch/powerpc/mm/book3s64/radix_tlb.c

@@ -987,7 +987,7 @@ void radix__flush_tlb_mm(struct mm_struct *mm)
 		}
 	}
 	preempt_enable();
-	mmu_notifier_invalidate_range(mm, 0, -1UL);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 EXPORT_SYMBOL(radix__flush_tlb_mm);
 
@@ -1021,7 +1021,7 @@ static void __flush_all_mm(struct mm_struct *mm, bool fullmm)
 			_tlbiel_pid_multicast(mm, pid, RIC_FLUSH_ALL);
 	}
 	preempt_enable();
-	mmu_notifier_invalidate_range(mm, 0, -1UL);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 
 void radix__flush_all_mm(struct mm_struct *mm)
@@ -1230,7 +1230,7 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
 	}
 out:
 	preempt_enable();
-	mmu_notifier_invalidate_range(mm, start, end);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 void radix__flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
@@ -1395,7 +1395,7 @@ static void __radix__flush_tlb_range_psize(struct mm_struct *mm,
 	}
 out:
 	preempt_enable();
-	mmu_notifier_invalidate_range(mm, start, end);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 void radix__flush_tlb_range_psize(struct mm_struct *mm, unsigned long start,

arch/x86/include/asm/tlbflush.h

@@ -283,7 +283,7 @@ static inline void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *b
 {
 	inc_mm_tlb_gen(mm);
 	cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm));
-	mmu_notifier_invalidate_range(mm, 0, -1UL);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 
 static inline void arch_flush_tlb_batched_pending(struct mm_struct *mm)

arch/x86/mm/tlb.c

@@ -1037,7 +1037,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 
 	put_flush_tlb_info();
 	put_cpu();
-	mmu_notifier_invalidate_range(mm, start, end);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 

drivers/iommu/amd/iommu_v2.c

@@ -355,9 +355,9 @@ static struct pasid_state *mn_to_state(struct mmu_notifier *mn)
 	return container_of(mn, struct pasid_state, mn);
 }
 
-static void mn_invalidate_range(struct mmu_notifier *mn,
+static void mn_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
-				struct mm_struct *mm,
+					struct mm_struct *mm,
-				unsigned long start, unsigned long end)
+					unsigned long start, unsigned long end)
 {
 	struct pasid_state *pasid_state;
 	struct device_state *dev_state;
@@ -391,8 +391,8 @@ static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
 }
 
 static const struct mmu_notifier_ops iommu_mn = {
-	.release		= mn_release,
+	.release			= mn_release,
-	.invalidate_range       = mn_invalidate_range,
+	.arch_invalidate_secondary_tlbs	= mn_arch_invalidate_secondary_tlbs,
 };
 
 static void set_pri_tag_status(struct pasid_state *pasid_state,

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c

@@ -186,9 +186,10 @@ static void arm_smmu_free_shared_cd(struct arm_smmu_ctx_desc *cd)
 	}
 }
 
-static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
+static void arm_smmu_mm_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
-					 struct mm_struct *mm,
+						struct mm_struct *mm,
-					 unsigned long start, unsigned long end)
+						unsigned long start,
+						unsigned long end)
 {
 	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
 	struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
@@ -247,9 +248,9 @@ static void arm_smmu_mmu_notifier_free(struct mmu_notifier *mn)
 }
 
 static const struct mmu_notifier_ops arm_smmu_mmu_notifier_ops = {
-	.invalidate_range	= arm_smmu_mm_invalidate_range,
+	.arch_invalidate_secondary_tlbs	= arm_smmu_mm_arch_invalidate_secondary_tlbs,
-	.release		= arm_smmu_mm_release,
+	.release			= arm_smmu_mm_release,
-	.free_notifier		= arm_smmu_mmu_notifier_free,
+	.free_notifier			= arm_smmu_mmu_notifier_free,
 };
 
 /* Allocate or get existing MMU notifier for this {domain, mm} pair */

drivers/iommu/intel/svm.c

@@ -219,9 +219,9 @@ static void intel_flush_svm_range(struct intel_svm *svm, unsigned long address,
 }
 
 /* Pages have been freed at this point */
-static void intel_invalidate_range(struct mmu_notifier *mn,
+static void intel_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
-				   struct mm_struct *mm,
+					struct mm_struct *mm,
-				   unsigned long start, unsigned long end)
+					unsigned long start, unsigned long end)
 {
 	struct intel_svm *svm = container_of(mn, struct intel_svm, notifier);
 
@@ -256,7 +256,7 @@ static void intel_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 
 static const struct mmu_notifier_ops intel_mmuops = {
 	.release = intel_mm_release,
-	.invalidate_range = intel_invalidate_range,
+	.arch_invalidate_secondary_tlbs = intel_arch_invalidate_secondary_tlbs,
 };
 
 static DEFINE_MUTEX(pasid_mutex);

drivers/misc/ocxl/link.c

@@ -491,9 +491,9 @@ void ocxl_link_release(struct pci_dev *dev, void *link_handle)
 }
 EXPORT_SYMBOL_GPL(ocxl_link_release);
 
-static void invalidate_range(struct mmu_notifier *mn,
+static void arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
-			     struct mm_struct *mm,
+					struct mm_struct *mm,
-			     unsigned long start, unsigned long end)
+					unsigned long start, unsigned long end)
 {
 	struct pe_data *pe_data = container_of(mn, struct pe_data, mmu_notifier);
 	struct ocxl_link *link = pe_data->link;
@@ -509,7 +509,7 @@ static void invalidate_range(struct mmu_notifier *mn,
 }
 
 static const struct mmu_notifier_ops ocxl_mmu_notifier_ops = {
-	.invalidate_range = invalidate_range,
+	.arch_invalidate_secondary_tlbs = arch_invalidate_secondary_tlbs,
 };
 
 static u64 calculate_cfg_state(bool kernel)

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
+	 * arch_invalidate_secondary_tlbs() is used to manage a non-CPU TLB
-	 * invalidate_range_start() and invalidate_range_end() when the
+	 * which shares page-tables with the CPU. The
-	 * VM has to free pages that where unmapped, but before the
+	 * invalidate_range_start()/end() callbacks should not be implemented as
-	 * pages are actually freed, or outside of _start()/_end() when
+	 * invalidate_secondary_tlbs() already catches the points in time when
-	 * a (remote) TLB is necessary.
+	 * an external TLB needs to be flushed.
 	 *
-	 * If invalidate_range() is used to manage a non-CPU TLB with
+	 * This requires arch_invalidate_secondary_tlbs() to be called while
-	 * shared page-tables, it not necessary to implement the
+	 * holding the ptl spin-lock and therefore this callback is not allowed
-	 * invalidate_range_start()/end() notifiers, as
+	 * to sleep.
-	 * 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
 	 *
-	 * Note that this function might be called with just a sub-range
+	 * This is called by architecture code whenever invalidating a TLB
-	 * of what was passed to invalidate_range_start()/end(), if
+	 * entry. It is assumed that any secondary TLB has the same rules for
-	 * called between those functions.
+	 * 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,
+	void (*arch_invalidate_secondary_tlbs)(
-				 struct mm_struct *mm,
+					struct mmu_notifier *subscription,
-				 unsigned long start,
+					struct mm_struct *mm,
-				 unsigned long end);
+					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,
+extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
-				  unsigned long start, unsigned long end);
+					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,
+static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
-				  unsigned long start, unsigned long end)
+					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)
 {
 }

mm/huge_memory.c

@@ -2120,8 +2120,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	if (is_huge_zero_pmd(*pmd)) {
 		/*
 		 * FIXME: Do we want to invalidate secondary mmu by calling
-		 * mmu_notifier_invalidate_range() see comments below inside
+		 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below
-		 * __split_huge_pmd() ?
+		 * inside __split_huge_pmd() ?
 		 *
 		 * We are going from a zero huge page write protected to zero
 		 * small page also write protected so it does not seems useful

mm/hugetlb.c

@@ -6649,8 +6649,9 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
 	else
 		flush_hugetlb_tlb_range(vma, start, end);
 	/*
-	 * No need to call mmu_notifier_invalidate_range() we are downgrading
+	 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() we are
-	 * page table protection not changing it to point to a new page.
+	 * downgrading page table protection not changing it to point to a new
+	 * page.
 	 *
 	 * See Documentation/mm/mmu_notifier.rst
 	 */
@@ -7294,7 +7295,7 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
 	i_mmap_unlock_write(vma->vm_file->f_mapping);
 	hugetlb_vma_unlock_write(vma);
 	/*
-	 * No need to call mmu_notifier_invalidate_range(), see
+	 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs(), see
 	 * Documentation/mm/mmu_notifier.rst.
 	 */
 	mmu_notifier_invalidate_range_end(&range);

mm/mmu_notifier.c

@@ -585,8 +585,8 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 }
 
-void __mmu_notifier_invalidate_range(struct mm_struct *mm,
+void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
-				  unsigned long start, unsigned long end)
+					unsigned long start, unsigned long end)
 {
 	struct mmu_notifier *subscription;
 	int id;
@@ -595,9 +595,10 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm,
 	hlist_for_each_entry_rcu(subscription,
 				 &mm->notifier_subscriptions->list, hlist,
 				 srcu_read_lock_held(&srcu)) {
-		if (subscription->ops->invalidate_range)
+		if (subscription->ops->arch_invalidate_secondary_tlbs)
-			subscription->ops->invalidate_range(subscription, mm,
+			subscription->ops->arch_invalidate_secondary_tlbs(
-							    start, end);
+				subscription, mm,
+				start, end);
 	}
 	srcu_read_unlock(&srcu, id);
 }
@@ -616,6 +617,16 @@ int __mmu_notifier_register(struct mmu_notifier *subscription,
 	mmap_assert_write_locked(mm);
 	BUG_ON(atomic_read(&mm->mm_users) <= 0);
 
+	/*
+	 * Subsystems should only register for invalidate_secondary_tlbs() or
+	 * invalidate_range_start()/end() callbacks, not both.
+	 */
+	if (WARN_ON_ONCE(subscription &&
+			 (subscription->ops->arch_invalidate_secondary_tlbs &&
+			 (subscription->ops->invalidate_range_start ||
+			  subscription->ops->invalidate_range_end))))
+		return -EINVAL;
+
 	if (!mm->notifier_subscriptions) {
 		/*
 		 * kmalloc cannot be called under mm_take_all_locks(), but we