Commit 52b54190 authored May 20, 2017 by Jan H. Schönherr Committed by Paolo Bonzini May 26, 2017

KVM: x86: Fix virtual wire mode



Intel SDM says, that at most one LAPIC should be configured with ExtINT
delivery. KVM configures all LAPICs this way. This causes pic_unlock()
to kick the first available vCPU from the internal KVM data structures.
If this vCPU is not the BSP, but some not-yet-booted AP, the BSP may
never realize that there is an interrupt.

Fix that by enabling ExtINT delivery only for the BSP.

This allows booting a Linux guest without a TSC in the above situation.
Otherwise the BSP gets stuck in calibrate_delay_converge().

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent e1d39b17

arch/x86/kvm/lapic.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1936,7 +1936,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
		for (i = 0; i < KVM_APIC_LVT_NUM; i++)
		kvm_lapic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED);
		apic_update_lvtt(apic);
		if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED))
		if (kvm_vcpu_is_reset_bsp(vcpu) &&
		kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED))
		kvm_lapic_set_reg(apic, APIC_LVT0,
		SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
		apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));

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