Commit e998fb1a authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Use page-track notifiers iff there are external users 



Disable the page-track notifier code at compile time if there are no
external users, i.e. if CONFIG_KVM_EXTERNAL_WRITE_TRACKING=n.  KVM itself
now hooks emulated writes directly instead of relying on the page-track
mechanism.

Provide a stub for "struct kvm_page_track_notifier_node" so that including
headers directly from the command line, e.g. for testing include guards,
doesn't fail due to a struct having an incomplete type.

Reviewed-by: default avatarYan Zhao <yan.y.zhao@intel.com>
Tested-by: default avatarYongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-23-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 58ea7cf7

arch/x86/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -1265,7 +1265,9 @@ struct kvm_arch { 
	 * create an NX huge page (without hanging the guest).

	 */

	struct list_head possible_nx_huge_pages;

#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING

	struct kvm_page_track_notifier_head track_notifier_head;

#endif

	/*

	 * Protects marking pages unsync during page faults, as TDP MMU page

	 * faults only take mmu_lock for read.  For simplicity, the unsync

arch/x86/include/asm/kvm_page_track.h

+15 −7
Original line number Diff line number Diff line
@@ -9,6 +9,14 @@ enum kvm_page_track_mode { 
	KVM_PAGE_TRACK_MAX,

};



void kvm_slot_page_track_add_page(struct kvm *kvm,

				  struct kvm_memory_slot *slot, gfn_t gfn,

				  enum kvm_page_track_mode mode);

void kvm_slot_page_track_remove_page(struct kvm *kvm,

				     struct kvm_memory_slot *slot, gfn_t gfn,

				     enum kvm_page_track_mode mode);



#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING

/*

 * The notifier represented by @kvm_page_track_notifier_node is linked into

 * the head which will be notified when guest is triggering the track event.
@@ -48,18 +56,18 @@ struct kvm_page_track_notifier_node { 
				    struct kvm_page_track_notifier_node *node);

};



void kvm_slot_page_track_add_page(struct kvm *kvm,

				  struct kvm_memory_slot *slot, gfn_t gfn,

				  enum kvm_page_track_mode mode);

void kvm_slot_page_track_remove_page(struct kvm *kvm,

				     struct kvm_memory_slot *slot, gfn_t gfn,

				     enum kvm_page_track_mode mode);



void

kvm_page_track_register_notifier(struct kvm *kvm,

				 struct kvm_page_track_notifier_node *n);

void

kvm_page_track_unregister_notifier(struct kvm *kvm,

				   struct kvm_page_track_notifier_node *n);

#else

/*

 * Allow defining a node in a structure even if page tracking is disabled, e.g.

 * to play nice with testing headers via direct inclusion from the command line.

 */

struct kvm_page_track_notifier_node {};

#endif /* CONFIG_KVM_EXTERNAL_WRITE_TRACKING */



#endif

arch/x86/kvm/mmu/page_track.c

+5 −5
Original line number Diff line number Diff line
@@ -194,6 +194,7 @@ bool kvm_slot_page_track_is_active(struct kvm *kvm, 
	return !!READ_ONCE(slot->arch.gfn_track[mode][index]);

}



#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING

void kvm_page_track_cleanup(struct kvm *kvm)

{

	struct kvm_page_track_notifier_head *head;
@@ -255,14 +256,13 @@ EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier); 
 * The node should figure out if the written page is the one that node is

 * interested in by itself.

 */

void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,

			  int bytes)

void __kvm_page_track_write(struct kvm *kvm, gpa_t gpa, const u8 *new, int bytes)

{

	struct kvm_page_track_notifier_head *head;

	struct kvm_page_track_notifier_node *n;

	int idx;



	head = &vcpu->kvm->arch.track_notifier_head;

	head = &kvm->arch.track_notifier_head;



	if (hlist_empty(&head->track_notifier_list))

		return;
@@ -273,8 +273,6 @@ void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, 
		if (n->track_write)

			n->track_write(gpa, new, bytes, n);

	srcu_read_unlock(&head->track_srcu, idx);



	kvm_mmu_track_write(vcpu, gpa, new, bytes);

}



/*
@@ -299,3 +297,5 @@ void kvm_page_track_delete_slot(struct kvm *kvm, struct kvm_memory_slot *slot) 
			n->track_remove_region(slot->base_gfn, slot->npages, n);

	srcu_read_unlock(&head->track_srcu, idx);

}



#endif

arch/x86/kvm/mmu/page_track.h

+25 −4
Original line number Diff line number Diff line
@@ -6,8 +6,6 @@ 


#include <asm/kvm_page_track.h>



int kvm_page_track_init(struct kvm *kvm);

void kvm_page_track_cleanup(struct kvm *kvm);



bool kvm_page_track_write_tracking_enabled(struct kvm *kvm);

int kvm_page_track_write_tracking_alloc(struct kvm_memory_slot *slot);
@@ -21,13 +19,36 @@ bool kvm_slot_page_track_is_active(struct kvm *kvm, 
				   const struct kvm_memory_slot *slot,

				   gfn_t gfn, enum kvm_page_track_mode mode);



void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,

			  int bytes);

#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING

int kvm_page_track_init(struct kvm *kvm);

void kvm_page_track_cleanup(struct kvm *kvm);



void __kvm_page_track_write(struct kvm *kvm, gpa_t gpa, const u8 *new, int bytes);

void kvm_page_track_delete_slot(struct kvm *kvm, struct kvm_memory_slot *slot);



static inline bool kvm_page_track_has_external_user(struct kvm *kvm)

{

	return !hlist_empty(&kvm->arch.track_notifier_head.track_notifier_list);

}

#else

static inline int kvm_page_track_init(struct kvm *kvm) { return 0; }

static inline void kvm_page_track_cleanup(struct kvm *kvm) { }



static inline void __kvm_page_track_write(struct kvm *kvm, gpa_t gpa,

					  const u8 *new, int bytes) { }

static inline void kvm_page_track_delete_slot(struct kvm *kvm,

					      struct kvm_memory_slot *slot) { }



static inline bool kvm_page_track_has_external_user(struct kvm *kvm) { return false; }



#endif /* CONFIG_KVM_EXTERNAL_WRITE_TRACKING */



static inline void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa,

					const u8 *new, int bytes)

{

	__kvm_page_track_write(vcpu->kvm, gpa, new, bytes);



	kvm_mmu_track_write(vcpu, gpa, new, bytes);

}



#endif /* __KVM_X86_PAGE_TRACK_H */