Re: [XEN PATCH v3 5/5] xen/arm: ffa: support notification

From: Julien Grall <julien@xen.org>
To: Bertrand Marquis <Bertrand.Marquis@arm.com>,
	Jens Wiklander <jens.wiklander@linaro.org>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	"patches@linaro.org" <patches@linaro.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Michal Orzel <michal.orzel@amd.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [XEN PATCH v3 5/5] xen/arm: ffa: support notification
Date: Fri, 26 Apr 2024 19:31:20 +0100	[thread overview]
Message-ID: <8b436c60-4ca3-4323-ab45-3af72ef60f7f@xen.org> (raw)
In-Reply-To: <A0908DCC-6E15-406B-8E29-F241B6EA8BE1@arm.com>

Hi Bertrand,

On 26/04/2024 10:20, Bertrand Marquis wrote:
>> +static inline struct domain *ffa_get_domain_by_vm_id(uint16_t vm_id)
>> +{
>> +    /* -1 to match ffa_get_vm_id() */
>> +    return get_domain_by_id(vm_id - 1);
>> +}
>> +
> 
> I think there is a global discussion to have on using get_domain_by_vm_id
> or rcu_lock_live_remote_domain_by_id to make sure the domain is not
> dying when we try to do something with it.
> 
> It does not need to be done here as there are other places to adapt but
> i wanted to raise the question.
> 
> I would like to know what you and also other maintainers think here.
> @Julien/Michal/Stefano ?

Good question. I think the intention is get_domain_by_id() should be 
called when you need a reference for longer.

I would consider to involve the REST in this discussion.

Cheers,

-- 
Julien Grall