Re: [Xen-devel] [XEN PATCH for-4.13 v7 10/11] libxl/xl: Overhaul passthrough setting logic

[Jürgen Groß <jgross@xxxxxxxx>]

On 23.10.19 15:00, Ian Jackson wrote:
> LIBXL_PASSTHROUGH_UNKNOWN (aka "ENABLED" in an earlier uncommitted
> version of this code) is doing double duty.  We actually need all of
> the following to be specifiable:
>    * "default": enable PT iff we have devices to
>      pass through specified in the initial config file.
>    * "enabled" (and fail if the platform doesn't support it).
>    * "disabled" (and reject future PT hotplug).
>    * "share_pt"/"sync_pt": enable PT and set a specific PT mode.
>
> Defaulting and error checking should be done in libxl.  So, we make
> several changes here.
>
> We introduce "enabled", and rename "unknown" to "default".
>
> We move all of the error checking and defaulting code from xl into
> libxl.  Now, libxl__domain_config_setdefault has all of the necessary
> information to get this right.  So we can do it all there.  Choosing
> the specific mode is arch-specific.
>
> We can also arrange to have only one place each which calculates
> (i) whether passthrough needs to be enabled because pt devices were
> specified (ii) whether pt_share can be used (for each arch).
>
> xl now only has to parse the enum in the same way as it parses all
> other enums.
>
> This change fixes a regression from earlier 4.13-pre: until recent
> changes, passthrough was only enabled by default if passthrough
> devices were specified.  We restore this behaviour.
>
> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Release-acked-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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