Re: [Xen-devel] [PATCH v2 2/4] VMX: Cleanup PI per-cpu blocking list when vcpu is destroyed

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.05.16 at 12:22, <feng.wu@xxxxxxxxx> wrote:

> 
>> -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Friday, May 27, 2016 9:49 PM
>> To: Wu, Feng <feng.wu@xxxxxxxxx>
>> Cc: andrew.cooper3@xxxxxxxxxx; dario.faggioli@xxxxxxxxxx;
>> george.dunlap@xxxxxxxxxxxxx; Tian, Kevin <kevin.tian@xxxxxxxxx>; xen-
>> devel@xxxxxxxxxxxxx; konrad.wilk@xxxxxxxxxx; keir@xxxxxxx 
>> Subject: Re: [PATCH v2 2/4] VMX: Cleanup PI per-cpu blocking list when vcpu 
> is
>> destroyed
>> 
>> >>> On 26.05.16 at 15:39, <feng.wu@xxxxxxxxx> wrote:
>> > --- a/xen/arch/x86/hvm/vmx/vmx.c
>> > +++ b/xen/arch/x86/hvm/vmx/vmx.c
>> > @@ -366,6 +366,7 @@ static void vmx_vcpu_destroy(struct vcpu *v)
>> >      vmx_destroy_vmcs(v);
>> >      vpmu_destroy(v);
>> >      passive_domain_destroy(v);
>> > +    vmx_pi_blocking_cleanup(v);
>> >  }
>> 
>> Isn't this redundant with the cleanup done when the last device
>> gets removed (via pci_release_devices()) during domain cleanup?
> 
> We need to handle the following two cases:
> - the last device gets removed (via 'xl pci-detach ...'), and the guest
> is running after that. The logical in vmx_pi_hooks_deassign() cover
> this case.
> - the guest is shutting down. It is covered here.

Exactly. Yet that latter case is already being taken care of by the
former: When the guest is shutting down, its last device will get
removed anyway.

Jan


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