KVM: x86: MMU: Move mapping_level_dirty_bitmap() call in mapping_level()

This is necessary to eliminate an extra memory slot search later.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 17 insertions, 18 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 2262728863de..890cd694c9a2 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -870,10 +870,16 @@ static bool mapping_level_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t large_gfn)
         return !gfn_to_memslot_dirty_bitmap(vcpu, large_gfn, true);
 }
 
-static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn)
+static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
+                         bool *force_pt_level)
 {
         int host_level, level, max_level;
 
+        if (likely(!*force_pt_level))
+                *force_pt_level = mapping_level_dirty_bitmap(vcpu, large_gfn);
+        if (unlikely(*force_pt_level))
+                return PT_PAGE_TABLE_LEVEL;
+
         host_level = host_mapping_level(vcpu->kvm, large_gfn);
 
         if (host_level == PT_PAGE_TABLE_LEVEL)
@@ -2962,14 +2968,13 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
 {
         int r;
         int level;
-        bool force_pt_level;
+        bool force_pt_level = false;
         pfn_t pfn;
         unsigned long mmu_seq;
         bool map_writable, write = error_code & PFERR_WRITE_MASK;
 
-        force_pt_level = mapping_level_dirty_bitmap(vcpu, gfn);
+        level = mapping_level(vcpu, gfn, &force_pt_level);
         if (likely(!force_pt_level)) {
-                level = mapping_level(vcpu, gfn);
                 /*
                  * This path builds a PAE pagetable - so we can map
                  * 2mb pages at maximum. Therefore check if the level
@@ -2979,8 +2984,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
                         level = PT_DIRECTORY_LEVEL;
 
                 gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
-        } else
-                level = PT_PAGE_TABLE_LEVEL;
+        }
 
         if (fast_page_fault(vcpu, v, level, error_code))
                 return 0;
@@ -3495,20 +3499,15 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
         if (r)
                 return r;
 
-        if (mapping_level_dirty_bitmap(vcpu, gfn) ||
-            !check_hugepage_cache_consistency(vcpu, gfn, PT_DIRECTORY_LEVEL))
-                force_pt_level = true;
-        else
-                force_pt_level = false;
-
+        force_pt_level = !check_hugepage_cache_consistency(vcpu, gfn,
+                                                           PT_DIRECTORY_LEVEL);
+        level = mapping_level(vcpu, gfn, &force_pt_level);
         if (likely(!force_pt_level)) {
-                level = mapping_level(vcpu, gfn);
                 if (level > PT_DIRECTORY_LEVEL &&
                     !check_hugepage_cache_consistency(vcpu, gfn, level))
                         level = PT_DIRECTORY_LEVEL;
                 gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
-        } else
-                level = PT_PAGE_TABLE_LEVEL;
+        }
 
         if (fast_page_fault(vcpu, gpa, level, error_code))
                 return 0;
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 8ebc3a5560ce..bf39d0f3efa9 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -744,9 +744,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
               &walker, user_fault, &vcpu->arch.write_fault_to_shadow_pgtable);
 
         if (walker.level >= PT_DIRECTORY_LEVEL && !is_self_change_mapping) {
-                force_pt_level = mapping_level_dirty_bitmap(vcpu, walker.gfn);
-                if (!force_pt_level) {
-                        level = min(walker.level, mapping_level(vcpu, walker.gfn));
+                level = mapping_level(vcpu, walker.gfn, &force_pt_level);
+                if (likely(!force_pt_level)) {
+                        level = min(walker.level, level);
                         walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
                 }
         } else