Usually, OS changes CR4.PGE bit to flush all global page, under this
case, no need reset mmu and just flush tlb

Signed-off-by: Xiao Guangrong <[email protected]>
---
 arch/x86/kvm/x86.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd5c3d3..2aaa6fb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -463,6 +463,15 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
        unsigned long old_cr4 = kvm_read_cr4(vcpu);
        unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
 
+       if (cr4 == old_cr4)
+               return;
+
+       if ((cr4 ^ old_cr4) == X86_CR4_PGE) {
+               kvm_mmu_sync_roots(vcpu);
+               kvm_mmu_flush_tlb(vcpu);
+               return;
+       }
+
        if (cr4 & CR4_RESERVED_BITS) {
                kvm_inject_gp(vcpu, 0);
                return;
-- 
1.6.1.2


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