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 <[email protected]>
---
 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);
+}
+
 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);
 
-- 
1.7.4

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