Re: [Xen-devel] [PATCH] public/hvm: Export the HVM_PARAM_CALLBACK_VIA ABI in the API

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.11.15 at 19:20, <andrew.cooper3@xxxxxxxxxx> wrote:
> --- a/xen/include/public/hvm/params.h
> +++ b/xen/include/public/hvm/params.h
> @@ -29,18 +29,21 @@
>   * Parameter space for HVMOP_{set,get}_param.
>   */
>  
> +#define HVM_PARAM_CALLBACK_IRQ 0
> +
>  /*
>   * How should CPU0 event-channel notifications be delivered?
> - * val[63:56] == 0: val[55:0] is a delivery GSI (Global System Interrupt).
> - * val[63:56] == 1: val[55:0] is a delivery PCI INTx line, as follows:
> - *                  Domain = val[47:32], Bus  = val[31:16],
> - *                  DevFn  = val[15: 8], IntX = val[ 1: 0]
> - * val[63:56] == 2: val[7:0] is a vector number, check for
> - *                  XENFEAT_hvm_callback_vector to know if this delivery
> - *                  method is available.
> + *
>   * If val == 0 then CPU0 event-channel notifications are not delivered.
> + * If val != 0, val[63:56] encodes the type, as follows:
>   */
> -#define HVM_PARAM_CALLBACK_IRQ 0
> +#define HVM_PARAM_CALLBACK_TYPE_GSI      0 /* val[55:0] is a delivery GSI */
> +#define HVM_PARAM_CALLBACK_TYPE_PCI_INTX 1 /* val[55:0] is a delivery PCI 
> INTx line:
> +                                              Domain = val[47:32], Bus  = 
> val[31:16],
> +                                              DevFn  = val[15: 8], IntX = 
> val[ 1: 0] */
> +#define HVM_PARAM_CALLBACK_TYPE_VECTOR   2 /* val[7:0] is a vector number, 
> check for
> +                                              XENFEAT_hvm_callback_vector to 
> know if
> +                                              this delivery method is 
> available. */

Would you not think that while cleaning this up, doing some
re-formatting would also help? I.e. Putting the comments on lines of
their own instead of at the end (even more deeply indented than
they were before)? Also the first two of these last three comments
are missing full stops.

Also considering

 * Attempting to use GSI 0 will actually disable callbacks

in your patch comments, I'd suggest extending the GSI comment to
state that it has to be a non-zero one.

Jan


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