Xen devel - Sep 2013 - [PATCH] xen/x86: add a comment regarding how to get the VCPU ID on HVM

Add a note to the public headers regarding how to get the VCPU ID for
HVM guests (on x86).

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Matt Wilson <msw@amazon.com>
---
This is what Linux PVHVM does AFAIK, and also what I've been using in
my FreeBSD PVHVM series, but it's not written anywere.
---
 xen/include/public/vcpu.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
index e888daf..a5ca44d 100644
--- a/xen/include/public/vcpu.h
+++ b/xen/include/public/vcpu.h
@@ -35,6 +35,9 @@
  * @cmd        == VCPUOP_??? (VCPU operation).
  * @vcpuid     == VCPU to operate on.
  * @extra_args == Operation-specific extra arguments (NULL if none).
+ *
+ * For x86 HVM domains that use VCPU operations the VCPU ID is the ACPI ID
+ * of the CPU, as fetched from the MADT table.
  */
 
 /*
-- 
1.7.7.5 (Apple Git-26)


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On Mon, Sep 23, 2013 at 06:55:29PM +0200, Roger Pau Monne
wrote:
> Add a note to the public headers regarding how to get the VCPU ID for
> HVM guests (on x86).
>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Matt Wilson <msw@amazon.com>
> ---
> This is what Linux PVHVM does AFAIK, and also what I''ve been using
in
> my FreeBSD PVHVM series, but it''s not written anywere.
What about rewording slightly to:

  For x86 HVM domains that use VCPU operations the VCPU ID is the ACPI
  Processor ID of the CPU (not to be confused with the APIC ID), as
  fetched from the MADT table.

The field is "ACPI Processor ID" in the spec.

Otherwise:

Acked-by: Matt Wilson <msw@amazon.com>

--msw
> ---
>  xen/include/public/vcpu.h |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
> index e888daf..a5ca44d 100644
> --- a/xen/include/public/vcpu.h
> +++ b/xen/include/public/vcpu.h
> @@ -35,6 +35,9 @@
>   * @cmd        == VCPUOP_??? (VCPU operation).
>   * @vcpuid     == VCPU to operate on.
>   * @extra_args == Operation-specific extra arguments (NULL if none).
> + *
> + * For x86 HVM domains that use VCPU operations the VCPU ID is the ACPI ID
> + * of the CPU, as fetched from the MADT table.
>   */
>  
>  /*