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

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On 03/02/2016 23:51, Bruce Rogers wrote:
> 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@suse.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) {
> 

KVM_MP_STATE_INIT_RECEIVED is what Intel calls the "wait for SIPI"
state.  The BSP never gets a SIPI, it goes straight to 0xFFFFFFF0
instead.  Can you explain the problem more in detail?

Paolo

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[PATCH 1/2] KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset Bruce Rogers <brogers@suse.com> - 2016-02-04 00:20 +0100
  [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Bruce Rogers <brogers@suse.com> - 2016-02-04 00:20 +0100
    Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Paolo Bonzini <pbonzini@redhat.com> - 2016-02-08 16:20 +0100
      Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Jan Kiszka <jan.kiszka@web.de> - 2016-02-08 16:30 +0100
        Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like  APs do "Bruce Rogers" <brogers@suse.com> - 2016-02-08 17:40 +0100
          Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Paolo Bonzini <pbonzini@redhat.com> - 2016-02-08 17:50 +0100
            Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like  APs do "Bruce Rogers" <brogers@suse.com> - 2016-02-08 18:30 +0100
              Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Paolo Bonzini <pbonzini@redhat.com> - 2016-02-08 18:50 +0100
            Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like  APs do "Bruce Rogers" <brogers@suse.com> - 2016-02-08 18:40 +0100
              Re: [PATCH 2/2] KVM: x86: allow BSP to handle INIT IPIs like APs do Jan Kiszka <jan.kiszka@web.de> - 2016-02-08 19:00 +0100
  Re: [PATCH 1/2] KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset Nadav Amit <nadav.amit@gmail.com> - 2016-02-04 00:20 +0100
    Re: [PATCH 1/2] KVM: x86: fix ordering of cr0 initialization  code in vmx_cpu_reset "Bruce Rogers" <brogers@suse.com> - 2016-02-04 00:40 +0100
  Re: [PATCH 1/2] KVM: x86: fix ordering of cr0 initialization code in  vmx_cpu_reset Paolo Bonzini <pbonzini@redhat.com> - 2016-02-08 16:10 +0100
    Re: [PATCH 1/2] KVM: x86: fix ordering of cr0 initialization  code in vmx_cpu_reset "Bruce Rogers" <brogers@suse.com> - 2016-02-08 17:30 +0100
      Re: [PATCH 1/2] KVM: x86: fix ordering of cr0 initialization code in  vmx_cpu_reset Paolo Bonzini <pbonzini@redhat.com> - 2016-02-08 17:50 +0100

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