linux-kernel - [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do

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Message-Id: <1454539876-8310-2-git-send-email-brogers@suse.com>
Date:	Wed,  3 Feb 2016 15:51:16 -0700
From:	Bruce Rogers <brogers@...e.com>
To:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	jan.kiszka@...mens.com, namit@...technion.ac.il,
	Bruce Rogers <brogers@...e.com>
Subject: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do

The INIT IPI event handler special cases the boot-strap processor
(BSP) handling, avoiding the same mp state handling which is done for
the other (AP) processors. Debugging a linux guest usage scenario of
avoiding a reboot through the bios for a crash on any processor via eg:
kexec -p /boot/vmlinuz --initrd=/boot/initrd --append="$(cat /proc/cmdline)\
maxcpus=1" led to identifying this change as the needed fix.

With this change, an AP can now startup the BSP without error.

Signed-off-by: Bruce Rogers <brogers@...e.com>
---
 arch/x86/kvm/lapic.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 36591fa..eda6bfb 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2170,10 +2170,7 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 	if (test_bit(KVM_APIC_INIT, &pe)) {
 		kvm_lapic_reset(vcpu, true);
 		kvm_vcpu_reset(vcpu, true);
-		if (kvm_vcpu_is_bsp(apic->vcpu))
-			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
-		else
-			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
+		vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
 	}
 	if (test_bit(KVM_APIC_SIPI, &pe) &&
 	    vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
-- 
1.9.0