netdev - Re: [PATCH v3 01/11] xen/manage: keep track of the on-going suspend mode

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Message-ID: <1ff91b30-3963-728e-aefb-57944197bdde@oracle.com>
Date:   Tue, 1 Jun 2021 10:18:36 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Anchal Agarwal <anchalag@...zon.com>
Cc:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
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        dwmw@...zon.co.uk
Subject: Re: [PATCH v3 01/11] xen/manage: keep track of the on-going suspend
 mode


On 5/28/21 5:50 PM, Anchal Agarwal wrote:

> That only fails during boot but not after the control jumps into the image. The
> non boot cpus are brought offline(freeze_secondary_cpus) and then online via cpu hotplug path. In that case xen_vcpu_setup doesn't invokes the hypercall again.


OK, that makes sense --- by that time VCPUs have already been registered. What I don't understand though is why resume doesn't fail every time --- xen_vcpu and xen_vcpu_info should be different practically always, shouldn't they? Do you observe successful resumes when the hypercall fails?


>
> Another line of thought is something what kexec does to come around this problem
> is to abuse soft_reset and issue it during syscore_resume or may be before the image get loaded.
> I haven't experimented with that yet as I am assuming there has to be a way to re-register vcpus during resume.


Right, that sounds like it should work.


-boris