Re: [Xen-devel] [PATCH v4] x86/apicv: fix RTC periodic timer and apicv issue

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.12.16 at 06:44, <xuquan8@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vmx/intr.c
> +++ b/xen/arch/x86/hvm/vmx/intr.c
> @@ -315,9 +315,13 @@ void vmx_intr_assist(void)
>          * Set eoi_exit_bitmap for periodic timer interrup to cause 
> EOI-induced VM
>          * exit, then pending periodic time interrups have the chance to be 
> injected
>          * for compensation
> +        * Set eoi_exit_bitmap for intack.vector when it's higher than pending
> +        * periodic time interrupts. This way we can guarantee there's always 
> a chance
> +        * to post periodic time interrupts when periodic time interrupts 
> becomes the
> +        * highest one
>          */
>          if (pt_vector != -1)
> -            vmx_set_eoi_exit_bitmap(v, pt_vector);
> +            vmx_set_eoi_exit_bitmap(v, intack.vector);

The comment does not clarify why max(pt_vector, intack.vector)
is not needed. And I'd expect you to add
ASSERT(intack.vector >= pt_vector) then, to prove this (and one
might argue that this addition could be sufficient documentation,
albeit perhaps a brief comment next to the assertion would help
readers of this non-trivial piece of code).

Jan


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