KVM: x86: preserve x2APIC LDR on INIT
authorRadim Krčmář <rkrcmar@redhat.com>
Fri, 22 May 2015 17:22:10 +0000 (19:22 +0200)
committerPaolo Bonzini <pbonzini@redhat.com>
Thu, 28 May 2015 08:43:36 +0000 (10:43 +0200)
Logical x2APIC stops working if we rewrite it with zeros.
The best references are SDM April 2015: 10.12.10.1 Logical Destination
Mode in x2APIC Mode

  [...], the LDR are initialized by hardware based on the value of
  x2APIC ID upon x2APIC state transitions.

and SDM April 2015: 10.12.10.2 Deriving Logical x2APIC ID from the Local
x2APIC ID

  The LDR initialization occurs whenever the x2APIC mode is enabled

Signed-off-by: Radim KrÄ\8dmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
arch/x86/kvm/lapic.c

index c2a7d8a7a414cd3716ead9ab19f77460439fda3b..c789e00dfa8b06e5853c7a55e7ed177d8e654f8a 100644 (file)
@@ -1594,7 +1594,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
        apic_set_reg(apic, APIC_DFR, 0xffffffffU);
        apic_set_spiv(apic, 0xff);
        apic_set_reg(apic, APIC_TASKPRI, 0);
-       kvm_apic_set_ldr(apic, 0);
+       if (!apic_x2apic_mode(apic))
+               kvm_apic_set_ldr(apic, 0);
        apic_set_reg(apic, APIC_ESR, 0);
        apic_set_reg(apic, APIC_ICR, 0);
        apic_set_reg(apic, APIC_ICR2, 0);