KVM: x86: don't reset root in kvm_mmu_setup()

Here is the code path which shows kvm_mmu_setup() is invoked after
kvm_mmu_create(). Since kvm_mmu_setup() is only invoked in this code path,
this means the root_hpa and prev_roots are guaranteed to be invalid. And
it is not necessary to reset it again.

    kvm_vm_ioctl_create_vcpu()
        kvm_arch_vcpu_create()
            vmx_create_vcpu()
                kvm_vcpu_init()
                    kvm_arch_vcpu_init()
                        kvm_mmu_create()
        kvm_arch_vcpu_setup()
            kvm_mmu_setup()
                kvm_init_mmu()

This patch set reset_roots to false in kmv_mmu_setup().

Fixes: 7404887c0167615787a58183a2c85b2b59116045
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e24ea7067373af69d258c46995007b0446a69fdc..5402c53a079bcd25c4729e942b3ddace56ff04fc 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5417,7 +5417,12 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu)
 {
        MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu.root_hpa));
 
-       kvm_init_mmu(vcpu, true);
+       /*
+        * kvm_mmu_setup() is called only on vCPU initialization.  
+        * Therefore, no need to reset mmu roots as they are not yet
+        * initialized.
+        */
+       kvm_init_mmu(vcpu, false);
 }
 
 static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,