No normal guest has any reason to change physical APIC IDs, and allowing this introduces bugs into APIC acceleration code.
Signed-off-by: Maxim Levitsky mlevitsk@redhat.com --- arch/x86/kvm/lapic.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 66b0eb0bda94e..56996aeca9881 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2046,10 +2046,20 @@ static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
switch (reg) { case APIC_ID: /* Local APIC ID */ - if (!apic_x2apic_mode(apic)) - kvm_apic_set_xapic_id(apic, val >> 24); - else + if (apic_x2apic_mode(apic)) { ret = 1; + break; + } + /* + * Don't allow setting APIC ID with any APIC acceleration + * enabled to avoid unexpected issues + */ + if (enable_apicv && ((val >> 24) != apic->vcpu->vcpu_id)) { + kvm_vm_bugged(apic->vcpu->kvm); + break; + } + + kvm_apic_set_xapic_id(apic, val >> 24); break;
case APIC_TASKPRI: @@ -2617,8 +2627,16 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s, bool set) { - if (apic_x2apic_mode(vcpu->arch.apic)) { - u32 *id = (u32 *)(s->regs + APIC_ID); + u32 *id = (u32 *)(s->regs + APIC_ID); + + if (!apic_x2apic_mode(vcpu->arch.apic)) { + /* Don't allow setting APIC ID with any APIC acceleration + * enabled to avoid unexpected issues + */ + if (enable_apicv && (*id >> 24) != vcpu->vcpu_id) + return -EINVAL; + } else { + u32 *ldr = (u32 *)(s->regs + APIC_LDR); u64 icr;