| Message ID | 4D8FF2D2.9070109@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 03/28/2011 04:30 AM, Xiao Guangrong wrote: > Simplely return from kvm_mmu_pte_write path if no shadow page is > write-protected, than we can avoid to walk all shadow pages and hold > mmu-lock > > Signed-off-by: Xiao Guangrong<xiaoguangrong@cn.fujitsu.com> > --- > arch/x86/kvm/mmu.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 2841805..ccac6c4 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -3219,6 +3219,11 @@ static void kvm_mmu_access_page(struct kvm_vcpu *vcpu, gfn_t gfn) > set_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte); > } > > +static bool need_track_pte_changed(struct kvm_vcpu *vcpu) > +{ > + return !tdp_enabled || mmu_is_nested(vcpu); > +} > + What happens if this vcpu is nested but another vcpu is not? Or if we have some indirect pages, but currently we're in non-nested mode? Suggest instead to keep track of the number of indirect pages across the guest. If it's zero, we can exit early. > void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, > const u8 *new, int bytes, > bool guest_initiated) > @@ -3233,6 +3238,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, > int level, npte, invlpg_counter, r, flooded = 0; > bool remote_flush, local_flush, zap_page; > > + if (!need_track_pte_changed(vcpu)) > + return; > + > zap_page = remote_flush = local_flush = false; > offset = offset_in_page(gpa); >
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 2841805..ccac6c4 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3219,6 +3219,11 @@ static void kvm_mmu_access_page(struct kvm_vcpu *vcpu, gfn_t gfn) set_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte); } +static bool need_track_pte_changed(struct kvm_vcpu *vcpu) +{ + return !tdp_enabled || mmu_is_nested(vcpu); +} + void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes, bool guest_initiated) @@ -3233,6 +3238,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, int level, npte, invlpg_counter, r, flooded = 0; bool remote_flush, local_flush, zap_page; + if (!need_track_pte_changed(vcpu)) + return; + zap_page = remote_flush = local_flush = false; offset = offset_in_page(gpa);