From: David Gibson <david@gibson.dropbear.id.au>
To: Greg Kurz <groug@kaod.org>
Cc: Laurent Vivier <lvivier@redhat.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
qemu-ppc@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [PATCH v2 0/2] spapr: Fix device unplug vs CAS or migration
Date: Mon, 17 Feb 2020 11:31:37 +1100 [thread overview]
Message-ID: <20200217003137.GB14136@umbus.fritz.box> (raw)
In-Reply-To: <158169247578.3465937.4013536808417411649.stgit@bahia.lan>
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On Fri, Feb 14, 2020 at 04:01:16PM +0100, Greg Kurz wrote:
> While working on getting rid of CAS reboot, I realized that we currently
> don't handle device hot unplug properly in the following situations:
>
> 1) if the device is unplugged between boot and CAS, SLOF doesn't handle
> the even, which is a known limitation. The device hence stays around
> forever (specifically, until some other event is emitted and the guest
> eventually completes the unplug or a reboot). Until we can teach SLOF
> to correctly process the full FDT at CAS, we should trigger a CAS reboot,
> like we already do for hotplug.
>
> 2) if the guest is migrated after the even was emitted but before the
> guest could process it, the destination is unaware of the pending
> unplug operation and doesn't remove the device when the guests
> releases it. The 'unplug_requested' field of the DRC is actually state
> that should be migrated.
>
> Changes since v1:
> - new spapr_drc_transient() helper that covers pending plug and unplug
> situations for both CAS and migration
> - as a mechanical consequence, fix unplug for CAS an migration in the
> same patch
Applied to ppc-for-5.0, thanks.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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prev parent reply other threads:[~2020-02-17 0:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 15:01 [PATCH v2 0/2] spapr: Fix device unplug vs CAS or migration Greg Kurz
2020-02-14 15:01 ` [PATCH v2 1/2] spapr: Don't use spapr_drc_needed() in CAS code Greg Kurz
2020-02-14 15:01 ` [PATCH v2 2/2] spapr: Fix handling of unplugged devices during CAS and migration Greg Kurz
2020-02-17 0:31 ` David Gibson [this message]
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