KVM: remove CONFIG_KVM_GENERIC_MMU_NOTIFIER

bonzini · bonzini · commit 407fd8b8d8cc · 2026-02-28T15:31:35.000+01:00
All architectures now use MMU notifier for KVM page table management.
Remove the Kconfig symbol and the code that is used when it is
disabled.

Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
@@ -21,7 +21,6 @@ menuconfig KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
 	select KVM_COMMON
 	select KVM_GENERIC_HARDWARE_ENABLING
-	select KVM_GENERIC_MMU_NOTIFIER
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
diff --git a/arch/loongarch/kvm/Kconfig b/arch/loongarch/kvm/Kconfig
@@ -28,7 +28,6 @@ config KVM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
-	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_MMIO
 	select VIRT_XFER_TO_GUEST_WORK
 	select SCHED_INFO
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
@@ -23,7 +23,6 @@ config KVM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_MMIO
-	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select HAVE_KVM_READONLY_MEM
 	help
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
@@ -38,7 +38,6 @@ config KVM_BOOK3S_64_HANDLER
 config KVM_BOOK3S_PR_POSSIBLE
 	bool
 	select KVM_MMIO
-	select KVM_GENERIC_MMU_NOTIFIER
 
 config KVM_BOOK3S_HV_POSSIBLE
 	bool
@@ -81,7 +80,6 @@ config KVM_BOOK3S_64_HV
 	tristate "KVM for POWER7 and later using hypervisor mode in host"
 	depends on KVM_BOOK3S_64 && PPC_POWERNV
 	select KVM_BOOK3S_HV_POSSIBLE
-	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_BOOK3S_HV_PMU
 	select CMA
 	help
@@ -203,7 +201,6 @@ config KVM_E500V2
 	depends on !CONTEXT_TRACKING_USER
 	select KVM
 	select KVM_MMIO
-	select KVM_GENERIC_MMU_NOTIFIER
 	help
 	  Support running unmodified E500 guest kernels in virtual machines on
 	  E500v2 host processors.
@@ -220,7 +217,6 @@ config KVM_E500MC
 	select KVM
 	select KVM_MMIO
 	select KVM_BOOKE_HV
-	select KVM_GENERIC_MMU_NOTIFIER
 	help
 	  Support running unmodified E500MC/E5500/E6500 guest kernels in
 	  virtual machines on E500MC/E5500/E6500 host processors.
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
@@ -625,7 +625,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		break;
 #endif
 	case KVM_CAP_SYNC_MMU:
-		BUILD_BUG_ON(!IS_ENABLED(CONFIG_KVM_GENERIC_MMU_NOTIFIER));
 		r = 1;
 		break;
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
@@ -30,7 +30,6 @@ config KVM
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_MMIO
 	select VIRT_XFER_TO_GUEST_WORK
-	select KVM_GENERIC_MMU_NOTIFIER
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
 	help
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
@@ -28,9 +28,7 @@ config KVM
 	select HAVE_KVM_INVALID_WAKEUPS
 	select HAVE_KVM_NO_POLL
 	select KVM_VFIO
-	select MMU_NOTIFIER
 	select VIRT_XFER_TO_GUEST_WORK
-	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_MMU_LOCKLESS_AGING
 	help
 	  Support hosting paravirtualized guest machines using the SIE
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
@@ -20,7 +20,6 @@ if VIRTUALIZATION
 config KVM_X86
 	def_tristate KVM if (KVM_INTEL != n || KVM_AMD != n)
 	select KVM_COMMON
-	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_ELIDE_TLB_FLUSH_IF_YOUNG
 	select KVM_MMU_LOCKLESS_AGING
 	select HAVE_KVM_IRQCHIP
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
@@ -253,7 +253,6 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
 #endif
 
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 union kvm_mmu_notifier_arg {
 	unsigned long attributes;
 };
@@ -275,7 +274,6 @@ struct kvm_gfn_range {
 bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
 bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
 bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
-#endif
 
 enum {
 	OUTSIDE_GUEST_MODE,
@@ -849,13 +847,12 @@ struct kvm {
 	struct hlist_head irq_ack_notifier_list;
 #endif
 
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 	struct mmu_notifier mmu_notifier;
 	unsigned long mmu_invalidate_seq;
 	long mmu_invalidate_in_progress;
 	gfn_t mmu_invalidate_range_start;
 	gfn_t mmu_invalidate_range_end;
-#endif
+
 	struct list_head devices;
 	u64 manual_dirty_log_protect;
 	struct dentry *debugfs_dentry;
@@ -2118,7 +2115,6 @@ extern const struct _kvm_stats_desc kvm_vm_stats_desc[];
 extern const struct kvm_stats_header kvm_vcpu_stats_header;
 extern const struct _kvm_stats_desc kvm_vcpu_stats_desc[];
 
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 static inline int mmu_invalidate_retry(struct kvm *kvm, unsigned long mmu_seq)
 {
 	if (unlikely(kvm->mmu_invalidate_in_progress))
@@ -2196,7 +2192,6 @@ static inline bool mmu_invalidate_retry_gfn_unsafe(struct kvm *kvm,
 
 	return READ_ONCE(kvm->mmu_invalidate_seq) != mmu_seq;
 }
-#endif
 
 #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
 
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
@@ -5,6 +5,7 @@ config KVM_COMMON
        bool
        select EVENTFD
        select INTERVAL_TREE
+       select MMU_NOTIFIER
        select PREEMPT_NOTIFIERS
 
 config HAVE_KVM_PFNCACHE
@@ -93,24 +94,16 @@ config HAVE_KVM_PM_NOTIFIER
 config KVM_GENERIC_HARDWARE_ENABLING
        bool
 
-config KVM_GENERIC_MMU_NOTIFIER
-       select MMU_NOTIFIER
-       bool
-
 config KVM_ELIDE_TLB_FLUSH_IF_YOUNG
-       depends on KVM_GENERIC_MMU_NOTIFIER
        bool
 
 config KVM_MMU_LOCKLESS_AGING
-       depends on KVM_GENERIC_MMU_NOTIFIER
        bool
 
 config KVM_GENERIC_MEMORY_ATTRIBUTES
-       depends on KVM_GENERIC_MMU_NOTIFIER
        bool
 
 config KVM_GUEST_MEMFD
-       depends on KVM_GENERIC_MMU_NOTIFIER
        select XARRAY_MULTI
        bool
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
@@ -502,7 +502,6 @@ void kvm_destroy_vcpus(struct kvm *kvm)
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_destroy_vcpus);
 
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)
 {
 	return container_of(mn, struct kvm, mmu_notifier);
@@ -901,15 +900,6 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
 	return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
 }
 
-#else  /* !CONFIG_KVM_GENERIC_MMU_NOTIFIER */
-
-static int kvm_init_mmu_notifier(struct kvm *kvm)
-{
-	return 0;
-}
-
-#endif /* CONFIG_KVM_GENERIC_MMU_NOTIFIER */
-
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
 static int kvm_pm_notifier_call(struct notifier_block *bl,
 				unsigned long state,
@@ -1226,10 +1216,8 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 out_err_no_debugfs:
 	kvm_coalesced_mmio_free(kvm);
 out_no_coalesced_mmio:
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 	if (kvm->mmu_notifier.ops)
 		mmu_notifier_unregister(&kvm->mmu_notifier, current->mm);
-#endif
 out_err_no_mmu_notifier:
 	kvm_disable_virtualization();
 out_err_no_disable:
@@ -1292,7 +1280,6 @@ static void kvm_destroy_vm(struct kvm *kvm)
 		kvm->buses[i] = NULL;
 	}
 	kvm_coalesced_mmio_free(kvm);
-#ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER
 	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
 	/*
 	 * At this point, pending calls to invalidate_range_start()
@@ -1311,9 +1298,6 @@ static void kvm_destroy_vm(struct kvm *kvm)
 		kvm->mn_active_invalidate_count = 0;
 	else
 		WARN_ON(kvm->mmu_invalidate_in_progress);
-#else
-	kvm_flush_shadow_all(kvm);
-#endif
 	kvm_arch_destroy_vm(kvm);
 	kvm_destroy_devices(kvm);
 	for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
