Re: [Xen-devel] [PATCH v2] xen/vcpu: Rework sanity checks in vcpu_create()

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Tue, Sep 11, 2018 at 12:48 PM Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
>
> Poisoning idle_vcpu[0] with the sanity debug value isn't actually a clever
> idea, because it passes a NULL pointer check but isn't a usable vcpu.  It is
> also the reason for the (!is_idle_domain(d) || vcpu_id) part of the existing
> sanity BUG_ON().
>
> Now that d->max_vcpus is appropriately set up before vcpu_create() is called,
> we can properly range check the requested vcpu_id.  Drop the BUG_ON() and
> replace it with code which is runtime safe but non-fatal.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> CC: Jason Andryuk <jandryuk@xxxxxxxxx>
>
> v2:
>  * Fix the tboot check following the un-poisioning of idle_vcpu[0]
>  * Exclude the idle domain from the next_in_list list, and vastly simplify the
>    linking logic.

Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>

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