On 03/10/2018 16:36, Nikita Leshenko wrote:
> On Wed, 2018-10-03 at 13:47 +0200, Paolo Bonzini wrote:
>> Commit b5861e5cf2fcf83031ea3e26b0a69d887adf7d21 introduced a check on
>> the interrupt-window and NMI-window CPU execution controls in order to
>> inject an external interrupt vmexit before the first guest instruction
>> executes.  However, when APIC virtualization is enabled the host does not
>> need a vmexit in order to inject an interrupt at the next interrupt window;
>> instead, it just places the interrupt vector in RVI and the processor will
>> inject it as soon as possible.  Therefore, on machines with APICv it is
>> not enough to check the CPU execution controls: the same scenario can also
>> happen if RVI>0.
>>
>> Fixes: b5861e5cf2fcf83031ea3e26b0a69d887adf7d21
>> Cc: Nikita Leshchenko <[email protected]>
>> Cc: Sean Christopherson <[email protected]>
>> Cc: Liran Alon <[email protected]>
>> Cc: Radim Krčmář <[email protected]>
>> Signed-off-by: Paolo Bonzini <[email protected]>
>> ---
>>  arch/x86/kvm/vmx.c | 16 +++++++++++-----
>>  1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 6ef2d5b139b9..c0c7689f0049 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -10280,6 +10280,11 @@ static void vmx_hwapic_isr_update(struct kvm_vcpu 
>> *vcpu, int max_isr)
>>      }
>>  }
>>  
>> +static u8 vmx_get_rvi(void)
>> +{
>> +    return vmcs_read16(GUEST_INTR_STATUS) & 0xff;
>> +}
>> +
>>  static void vmx_set_rvi(int vector)
>>  {
>>      u16 status;
>> @@ -12593,10 +12598,13 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu 
>> *vcpu, u32 *exit_qual)
>>      struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
>>      bool from_vmentry = !!exit_qual;
>>      u32 dummy_exit_qual;
>> -    u32 vmcs01_cpu_exec_ctrl;
>> +    bool evaluate_pending_interrupts;
>>      int r = 0;
>>  
>> -    vmcs01_cpu_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
>> +    evaluate_pending_interrupts = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
>> +            (CPU_BASED_VIRTUAL_INTR_PENDING | 
>> CPU_BASED_VIRTUAL_NMI_PENDING);
>> +    if (enable_apicv && kvm_vcpu_apicv_active(vcpu))
>> +            evaluate_pending_interrupts |= vmx_get_rvi() > 0;
> 
> You should check for RVI > VPPR, similarly to how it is done in
> vmx_guest_apic_has_interrupt().
> 
> Also, now that you introduced vmx_get_rvi(), it could be nice to use it
> in vmx_guest_apic_has_interrupt() as well.
> 
> Apart from that, looks good.
> 
> Reviewed-by: Nikita Leshenko <[email protected]>

Nevermind, vPPR is of course available in vcpu->arch.apic since this is
L1.  So v2 is on the way.

Paolo

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