Re: [Xen-devel] [PATCH v5 1/7] VMX: Statically assign two PI hooks

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Wu, Feng
> Sent: Tuesday, October 11, 2016 8:58 AM
> 
> PI hooks: vmx_pi_switch_from() and vmx_pi_switch_to() are
> needed even when any previously assigned device is detached
> from the domain. Since 'SN' bit is also used to control the
> CPU side PI and we change the state of SN bit in these two
> functions, then evaluate this bit in vmx_deliver_posted_intr()
> when trying to deliver the interrupt in posted way via software.
> The problem is if we deassign the hooks while the vCPU is runnable
> in the runqueue with 'SN' set, all the furture notificaton event
> will be suppressed. This patch makes these two hooks statically
> assigned.

Your patch has only one hook statically assigned...

> 
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> ---
> v5:
> - Zap "pi_switch_from" hook
> 
>  xen/arch/x86/hvm/vmx/vmx.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 3d330b6..623d5bc 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -147,6 +147,11 @@ static void vmx_pi_switch_from(struct vcpu *v)
>      pi_set_sn(pi_desc);
>  }
> 
> +/*
> + * In fact, we can remove this hooks inside itself if no new device is in the
> + * process of getting assigned and "from" hook is NULL. However, it is not
> + * straightforward to find a clear solution, so just leave it here.
> + */
>  static void vmx_pi_switch_to(struct vcpu *v)
>  {
>      struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
> @@ -221,9 +226,8 @@ void vmx_pi_hooks_deassign(struct domain *d)
>      ASSERT(d->arch.hvm_domain.vmx.vcpu_block);
> 
>      d->arch.hvm_domain.vmx.vcpu_block = NULL;
> -    d->arch.hvm_domain.vmx.pi_switch_from = NULL;
> -    d->arch.hvm_domain.vmx.pi_switch_to = NULL;
>      d->arch.hvm_domain.vmx.pi_do_resume = NULL;
> +    d->arch.hvm_domain.vmx.pi_switch_from = NULL;
>  }
> 
>  static int vmx_domain_initialise(struct domain *d)
> --
> 2.1.0


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