kvm: x86: Use fast CR3 switch for nested VMX
Use the fast CR3 switch mechanism to locklessly change the MMU root
page when switching between L1 and L2. The switch from L2 to L1 should
always go through the fast path, while the switch from L1 to L2 should
go through the fast path if L1's CR3/EPTP for L2 hasn't changed
since the last time.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cbe31b9..c6ea892 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10741,11 +10741,11 @@ static int nested_ept_init_mmu_context(struct kvm_vcpu *vcpu)
if (!valid_ept_address(vcpu, nested_ept_get_cr3(vcpu)))
return 1;
- kvm_mmu_unload(vcpu);
kvm_init_shadow_ept_mmu(vcpu,
to_vmx(vcpu)->nested.msrs.ept_caps &
VMX_EPT_EXECUTE_ONLY_BIT,
- nested_ept_ad_enabled(vcpu));
+ nested_ept_ad_enabled(vcpu),
+ nested_ept_get_cr3(vcpu));
vcpu->arch.mmu.set_cr3 = vmx_set_cr3;
vcpu->arch.mmu.get_cr3 = nested_ept_get_cr3;
vcpu->arch.mmu.inject_page_fault = nested_ept_inject_page_fault;
@@ -11342,12 +11342,16 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
return 1;
}
}
-
- vcpu->arch.cr3 = cr3;
- __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
}
- kvm_mmu_reset_context(vcpu);
+ if (!nested_ept)
+ kvm_mmu_new_cr3(vcpu, cr3);
+
+ vcpu->arch.cr3 = cr3;
+ __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
+
+ kvm_init_mmu(vcpu, false);
+
return 0;
}