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 Krčmář <[email protected]> --- arch/x86/kvm/lapic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index c2a7d8a7a414..c789e00dfa8b 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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); -- 2.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
