Re: [Xen-devel] [PATCH v4 02/12] livepatch: Allow to override inter-modules buildid dependency

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 9/28/19 4:12 PM, Pawel Wieczorkiewicz wrote:
> By default Livepatch enforces the following buildid-based dependency
> chain between livepatch modules:
>   1) first module depends on given hypervisor buildid
>   2) every consecutive module depends on previous module's buildid
> This way proper livepatch stack order is maintained and enforced.
> While it is important for production livepatches it limits agility and
> blocks usage of testing or debug livepatches. These kinds of livepatch
> modules are typically expected to be loaded at any time irrespective
> of current state of the modules stack.
> 
> To enable testing and debug livepatches allow user dynamically ignore
> the inter-modules dependency. In this case only hypervisor buildid
> match is verified and enforced.
> 
> To allow userland pass additional paremeters for livepatch actions
> add support for action flags.
> Each of the apply, revert, unload and revert action gets additional
> 64-bit parameter 'flags' where extra flags can be applied in a mask
> form.
> Initially only one flag '--nodeps' is added for the apply action.
> This flag modifies the default buildid dependency check as described
> above.
> The global sysctl interface input flag parameter is defined with a
> single corresponding flag macro:
>   LIVEPATCH_ACTION_APPLY_NODEPS (1 << 0)
> 
> The userland xen-livepatch tool is modified to support the '--nodeps'
> flag for apply and load commands. A general mechanism for specifying
> more flags in the future for apply and other action is however added.
> 
> Signed-off-by: Pawel Wieczorkiewicz <wipawel@xxxxxxxxx>
> Reviewed-by: Andra-Irina Paraschiv <andraprs@xxxxxxxxxx>
> Reviewed-by: Eslam Elnikety <elnikety@xxxxxxxxx>
> Reviewed-by: Petre Eftime <epetre@xxxxxxxxxx>
> Reviewed-by: Leonard Foerster <foersleo@xxxxxxxxx>
> Reviewed-by: Martin Pohlack <mpohlack@xxxxxxxxx>
> Reviewed-by: Norbert Manthey <nmanthey@xxxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> Changed since v3:
>   * simplified loop in xen-livepatch.c
> 
Reviewed-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

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