From: David Gibson <david@gibson.dropbear.id.au>
To: Greg Kurz <groug@kaod.org>
Cc: aik@ozlabs.ru, qemu-ppc@nongnu.org, clg@kaod.org, qemu-devel@nongnu.org
Subject: Re: [RFC for-5.1 4/4] spapr: Don't allow unplug of NVLink2 devices
Date: Fri, 27 Mar 2020 10:56:15 +1100 [thread overview]
Message-ID: <20200326235615.GD456060@umbus.fritz.box> (raw)
In-Reply-To: <20200326132740.6f305012@bahia.lan>
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On Thu, Mar 26, 2020 at 01:27:40PM +0100, Greg Kurz wrote:
> On Thu, 26 Mar 2020 16:40:09 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > Currently, we can't properly handle unplug of NVLink2 devices, because we
> > don't have code to tear down their special memory resources. There's not
> > a lot of impetus to implement that. Since hardware NVLink2 devices can't
> > be hot unplugged, the guest side drivers don't usually support unplug
> > anyway.
> >
> > Therefore, simply prevent unplug of NVLink2 devices.
> >
>
> This could maybe considered as a valid fix for 5.0 since this prevents
> guest crashes IIUC. But since this requires the two preliminary cleanup
> patches, I understand you may prefer to postpone that to 5.1.
Yeah, it's arguably a bug, but not a regression, so I'm inclined to
leave it to 5.1.
>
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
>
> Reviewed-by: Greg Kurz <groug@kaod.org>
>
> > hw/ppc/spapr_pci.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> > index 55ca9dee1e..5c8262413a 100644
> > --- a/hw/ppc/spapr_pci.c
> > +++ b/hw/ppc/spapr_pci.c
> > @@ -1666,6 +1666,11 @@ static void spapr_pci_unplug_request(HotplugHandler *plug_handler,
> > return;
> > }
> >
> > + if (spapr_phb_is_nvlink_dev(pdev, phb)) {
> > + error_setg(errp, "PCI: Cannot unplug NVLink2 devices");
> > + return;
> > + }
> > +
> > /* ensure any other present functions are pending unplug */
> > if (PCI_FUNC(pdev->devfn) == 0) {
> > for (i = 1; i < 8; i++) {
>
--
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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next prev parent reply other threads:[~2020-03-27 1:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 5:40 [RFC for-5.1 0/4] Better handling of attempt NVLink2 unplug David Gibson
2020-03-26 5:40 ` [RFC for-5.1 1/4] spapr: Refactor locating NVLink2 devices for device tree creation David Gibson
2020-03-26 11:57 ` Greg Kurz
2020-03-26 23:55 ` David Gibson
2020-03-26 5:40 ` [RFC for-5.1 2/4] spapr: Helper to determine if a device is NVLink2 related David Gibson
2020-03-26 11:58 ` Greg Kurz
2020-03-26 5:40 ` [RFC for-5.1 3/4] spapr: Fix failure path for attempting to hot unplug PCI bridges David Gibson
2020-03-26 12:18 ` Greg Kurz
2020-03-26 23:54 ` David Gibson
2020-03-26 5:40 ` [RFC for-5.1 4/4] spapr: Don't allow unplug of NVLink2 devices David Gibson
2020-03-26 12:27 ` Greg Kurz
2020-03-26 23:56 ` David Gibson [this message]
2020-03-28 12:32 ` Alexey Kardashevskiy
2020-03-31 3:25 ` David Gibson
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