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KVM: x86: MMU: Initialize force_pt_level before calling mapping_level()

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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 <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2015-10-19 15:13:29 +09:00 committed by Paolo Bonzini
parent 5690891bce
commit 8c85ac1c0a
2 changed files with 5 additions and 4 deletions
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7
arch/x86/kvm/mmu.c
View File

@ -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;

2
arch/x86/kvm/paging_tmpl.h
View File

@ -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;