| Message ID | 20151019151329.cf4b7cbbfe1fdb15bb756d93@lab.ntt.co.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 19/10/2015 08:13, Takuya Yoshikawa wrote: > 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> > --- > 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 dd2a7c6..7d85bca 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 bf39d0f..b41faa9 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; > > Looks good, thanks. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index dd2a7c6..7d85bca 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 bf39d0f..b41faa9 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;
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> --- arch/x86/kvm/mmu.c | 7 ++++--- arch/x86/kvm/paging_tmpl.h | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-)