Commit ac101b7c authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Avoid multiple hash lookups in kvm_get_mmu_page() 



Refactor for_each_valid_sp() to take the list of shadow pages instead of
retrieving it from a gfn to avoid doing the gfn->list hash and lookup
multiple times during kvm_get_mmu_page().

Cc: Peter Feiner <pfeiner@google.com>
Cc: Jon Cargille <jcargill@google.com>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200623194027.23135-2-sean.j.christopherson@intel.com>
Reviewed-By: default avatarJon Cargille <jcargill@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4cb5b77e

arch/x86/kvm/mmu/mmu.c

+9 −8
Original line number Diff line number Diff line
@@ -2243,15 +2243,14 @@ static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, 
static void kvm_mmu_commit_zap_page(struct kvm *kvm,

				    struct list_head *invalid_list);





#define for_each_valid_sp(_kvm, _sp, _gfn)				\

	hlist_for_each_entry(_sp,					\

	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \

#define for_each_valid_sp(_kvm, _sp, _list)				\

	hlist_for_each_entry(_sp, _list, hash_link)			\

		if (is_obsolete_sp((_kvm), (_sp))) {			\

		} else



#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn)			\

	for_each_valid_sp(_kvm, _sp, _gfn)				\

	for_each_valid_sp(_kvm, _sp,					\

	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)])	\

		if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else



static inline bool is_ept_sp(struct kvm_mmu_page *sp)
@@ -2462,6 +2461,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
					     unsigned int access)

{

	union kvm_mmu_page_role role;

	struct hlist_head *sp_list;

	unsigned quadrant;

	struct kvm_mmu_page *sp;

	bool need_sync = false;
@@ -2481,7 +2481,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
		quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;

		role.quadrant = quadrant;

	}

	for_each_valid_sp(vcpu->kvm, sp, gfn) {



	sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];

	for_each_valid_sp(vcpu->kvm, sp, sp_list) {

		if (sp->gfn != gfn) {

			collisions++;

			continue;
@@ -2518,8 +2520,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 


	sp->gfn = gfn;

	sp->role = role;

	hlist_add_head(&sp->hash_link,

		&vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]);

	hlist_add_head(&sp->hash_link, sp_list);

	if (!direct) {

		/*

		 * we should do write protection before syncing pages