From 8c85ac1c0a1b41299370857765bc0950666ed5d9 Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Mon, 19 Oct 2015 15:13:29 +0900 Subject: [PATCH] KVM: x86: MMU: Initialize force_pt_level before calling mapping_level() Commit fd1369021878 ("KVM: x86: MMU: Move mapping_level_dirty_bitmap() call in mapping_level()") forgot to initialize force_pt_level to false in FNAME(page_fault)() before calling mapping_level() like nonpaging_map() does. This can sometimes result in forcing page table level mapping unnecessarily. Fix this and move the first *force_pt_level check in mapping_level() before kvm_vcpu_gfn_to_memslot() call to make it a bit clearer that the variable must be initialized before mapping_level() gets called. This change can also avoid calling kvm_vcpu_gfn_to_memslot() when !check_hugepage_cache_consistency() check in tdp_page_fault() forces page table level mapping. Signed-off-by: Takuya Yoshikawa Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu.c | 7 ++++--- arch/x86/kvm/paging_tmpl.h | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index dd2a7c6ec2ca..7d85bcae3332 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -886,10 +886,11 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn, int host_level, level, max_level; struct kvm_memory_slot *slot; - slot = kvm_vcpu_gfn_to_memslot(vcpu, large_gfn); + if (unlikely(*force_pt_level)) + return PT_PAGE_TABLE_LEVEL; - if (likely(!*force_pt_level)) - *force_pt_level = !memslot_valid_for_gpte(slot, true); + slot = kvm_vcpu_gfn_to_memslot(vcpu, large_gfn); + *force_pt_level = !memslot_valid_for_gpte(slot, true); if (unlikely(*force_pt_level)) return PT_PAGE_TABLE_LEVEL; diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index bf39d0f3efa9..b41faa91a6f9 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -698,7 +698,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code, int r; pfn_t pfn; int level = PT_PAGE_TABLE_LEVEL; - bool force_pt_level; + bool force_pt_level = false; unsigned long mmu_seq; bool map_writable, is_self_change_mapping; -- 2.20.1