RE: [PATCH for-4.14] docs/ucode: Extend runtime microcode loading documentation

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Sent: 01 June 2020 14:40
> To: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>; George Dunlap 
> <George.Dunlap@xxxxxxxxxxxxx>; Ian
> Jackson <ian.jackson@xxxxxxxxxx>; Jan Beulich <JBeulich@xxxxxxxx>; Konrad 
> Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx>; Stefano Stabellini <sstabellini@xxxxxxxxxx>; Wei 
> Liu <wl@xxxxxxx>; Julien
> Grall <julien@xxxxxxx>; Paul Durrant <paul@xxxxxxx>
> Subject: [PATCH for-4.14] docs/ucode: Extend runtime microcode loading 
> documentation
> 
> Extend the disclaimer about runtime loading.  While we've done our best to
> make the mechaism reliable, the safety of late loading does ultimately depend
> on the contents of the blobs.
> 
> Extend the xen-ucode portion with examples of how to use it.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Paul Durrant <paul@xxxxxxx>
> ---
>  docs/admin-guide/microcode-loading.rst | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/docs/admin-guide/microcode-loading.rst 
> b/docs/admin-guide/microcode-loading.rst
> index 5f0f661a2e..8cd5d0351b 100644
> --- a/docs/admin-guide/microcode-loading.rst
> +++ b/docs/admin-guide/microcode-loading.rst
> @@ -104,8 +104,8 @@ modules to find any CPIO archives, and search the archive 
> for the applicable
>  file.  Xen will stop searching at the first match.
> 
> 
> -Run time microcode loading
> ---------------------------
> +Runtime microcode loading
> +-------------------------
> 
>  .. warning::
> 
> @@ -113,7 +113,23 @@ Run time microcode loading
>     or at boot time.  Not all microcode updates (or parts thereof) can be
>     applied at runtime.
> 
> -The ``xen-ucode`` utility can be used to initiate a runtime microcode load.
> +   Given the proprietry nature of microcode, we are unable to make any claim

s/proprietry/proprietary

with that fixed this is...

Release-acked-by: Paul Durrant <paul@xxxxxxx>

> +   that a runtime microcode is risk-free.  Any runtime microcode loading 
> needs
> +   adequate testing on a dev instance before being rolled out to production
> +   systems.
> +
> +The ``xen-ucode`` utility can be used to initiate a runtime microcode load::
> +
> +  [root@host ~]# xen-ucode
> +  xen-ucode: Xen microcode updating tool
> +  Usage: xen-ucode <microcode blob>
> +  [root@host ~]#
> +
> +e.g. With a Linux dom0 on a Haswell system::
> +
> +  [root@host ~]# xen-ucode /lib/firmware/intel-ucode/06-3c-03
> +  [root@host ~]#
> +
>  It will pass the blob to Xen, which will check to see whether the blob is
>  correct for the processor, and newer than the running microcode.
> 
> --
> 2.11.0