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: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200623194027.23135-2-sean.j.christopherson@intel.com>
Reviewed-By: Jon Cargille <jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 03ce2ca..7133713 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -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