Re: [PATCH 1/2] xen/cpupool: Reject attempts to add a domain to CPUPOOLID_NONE

From: Juergen Gross <jgross@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xenproject.org>
Cc: Dario Faggioli <dfaggioli@suse.com>,
	Luca Fancellu <luca.fancellu@arm.com>
Subject: Re: [PATCH 1/2] xen/cpupool: Reject attempts to add a domain to CPUPOOLID_NONE
Date: Wed, 18 May 2022 12:24:31 +0200	[thread overview]
Message-ID: <067cc1f8-bd82-f52f-3c01-b71fd7f82e6f@suse.com> (raw)
In-Reply-To: <20220517194113.2574-2-andrew.cooper3@citrix.com>


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On 17.05.22 21:41, Andrew Cooper wrote:
> c/s cfc52148444f ("xen/domain: Reduce the quantity of initialisation for
> system domains") removed the path in domain_create() which called
> sched_init_domain() with CPUPOOLID_NONE for system domains.
> 
> Arguably, that changeset should have cleaned up this path too.
> 
> However, c/s 92ea9c54fc81 ("arm/dom0less: assign dom0less guests to cpupools")
> changed domain_create() from using a hardcoded poolid of 0, to using a value
> passed by the toolstack.
> 
> While CPUPOOLID_NONE is an internal constant, userspace can pass -1 for the
> cpupool_id parameter and attempt to construct a real domain using default ops,
> which at a minimum will fail the assertion in dom_scheduler().
> 
> Fixes: 92ea9c54fc81 ("arm/dom0less: assign dom0less guests to cpupools")
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

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