[PATCH] kvm/svm: fixed a potential register value inconsistent with variable ldr_reg

[彭浩(Richard)]

If the ldr value is read out to zero, it does not call avic_ldr_write to update
the virtual register, but the variable ldr_reg is updated.

Fixes: 98d90582be2e ("SVM: Fix AVIC DFR and LDR handling")
Signed-off-by: Peng Hao <richard.peng@xxxxxxxx>
---
 arch/x86/kvm/svm/avic.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 8c550999ace0..318735e0f2d0 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -417,7 +417,6 @@ static void avic_invalidate_logical_id_entry(struct kvm_vcpu *vcpu)

 static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
 {
-       int ret = 0;
        struct vcpu_svm *svm = to_svm(vcpu);
        u32 ldr = kvm_lapic_get_reg(vcpu->arch.apic, APIC_LDR);
        u32 id = kvm_xapic_id(vcpu->arch.apic);
@@ -427,13 +426,16 @@ static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)

        avic_invalidate_logical_id_entry(vcpu);

-       if (ldr)
+       if (ldr) {
+               int ret;
                ret = avic_ldr_write(vcpu, id, ldr);

-       if (!ret)
-               svm->ldr_reg = ldr;
-
-       return ret;
+               if (!ret)
+                       svm->ldr_reg = ldr;
+               else
+                       return ret;
+       }
+       return 0;
}

 static int avic_handle_apic_id_update(struct kvm_vcpu *vcpu)
--
2.18.4