From: Igor Mammedov <imammedo@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
qemu-devel@nongnu.org, "Eduardo Habkost" <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH 0/6] RfC: try improve native hotplug for pcie root ports
Date: Fri, 12 Nov 2021 13:17:14 +0100 [thread overview]
Message-ID: <20211112131714.5a54eb8a@redhat.com> (raw)
In-Reply-To: <20211112111528.i43jhiybvwc2eyfz@sirius.home.kraxel.org>
On Fri, 12 Nov 2021 12:15:28 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:
> On Thu, Nov 11, 2021 at 10:39:59AM -0500, Michael S. Tsirkin wrote:
> > On Thu, Nov 11, 2021 at 01:09:05PM +0100, Gerd Hoffmann wrote:
> > > Hi,
> > >
> > > > When the acpihp driver is used the linux kernel will just call the aml
> > > > methods and I suspect the pci device will stay invisible then because
> > > > nobody flips the slot power control bit (with native-hotplug=on, for
> > > > native-hotplug=off this isn't a problem of course).
> > >
> > > Hmm, on a quick smoke test with both patch series (mine + igors) applied
> > > everything seems to work fine on a quick glance. Dunno why. Maybe the
> > > pcieport driver turns on slot power even in case pciehp is not active.
>
> Digged deeper. Updating power status is handled by the plug() callback,
> which is never called in case acpi hotplug is active. The guest seems
> to never touch slot power control either, so it's working fine. Still
> feels a bit fragile though.
>
> > Well power and hotplug capabilities are mostly unrelated, right?
>
> At least they are separate slot capabilities. The linux pciehp driver
> checks whenever the power control is present before using it, so having
> PwrCtrl- HotPlug+ seems to be a valid combination.
>
> We even have an option for that: pcie-root-port.power_controller_present
>
> So flipping that to off in case apci hotplug is active should make sure
> we never run into trouble with pci devices being powered off.
>
> Igor? Can you add that to your patch series?
Sorry, saw it too late.
I'll test idea with my set of guests to see if there are any adverse effects.
> > I feel switching to native so late would be inappropriate, looks more
> > like a feature than a bugfix. Given that - we need Igor's patches.
> > Given that - would you say I should apply yours?
>
> I think when setting power_controller_present=off for acpi hotplug it is
> safe to merge both mine and igor's.
>
> take care,
> Gerd
>
next prev parent reply other threads:[~2021-11-12 12:19 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 12:04 [PATCH 0/6] RfC: try improve native hotplug for pcie root ports Gerd Hoffmann
2021-10-11 12:04 ` [PATCH 1/6] pci: implement power state Gerd Hoffmann
2021-10-11 12:05 ` [PATCH 2/6] pcie: implement slow power control for pcie root ports Gerd Hoffmann
2021-10-11 12:05 ` [PATCH 3/6] pcie: add power indicator blink check Gerd Hoffmann
2021-11-15 11:29 ` Michael S. Tsirkin
2021-11-15 14:52 ` Gerd Hoffmann
2021-10-11 12:05 ` [PATCH 4/6] pcie: factor out pcie_cap_slot_unplug() Gerd Hoffmann
2021-10-11 12:05 ` [PATCH 5/6] pcie: fast unplug when slot power is off Gerd Hoffmann
2021-10-12 5:56 ` Michael S. Tsirkin
2021-10-12 6:46 ` Gerd Hoffmann
2021-10-11 12:05 ` [PATCH 6/6] pcie: expire pending delete Gerd Hoffmann
2021-10-11 12:49 ` Michael S. Tsirkin
2021-10-12 5:30 ` Gerd Hoffmann
2021-10-12 5:46 ` Michael S. Tsirkin
2021-10-12 6:44 ` Gerd Hoffmann
2021-10-12 7:01 ` Michael S. Tsirkin
2021-10-18 15:36 ` [PATCH 0/6] RfC: try improve native hotplug for pcie root ports Michael S. Tsirkin
2021-10-19 5:21 ` Gerd Hoffmann
2021-10-19 5:46 ` Michael S. Tsirkin
2021-10-19 6:29 ` Gerd Hoffmann
2021-11-01 21:47 ` Michael S. Tsirkin
2021-11-02 12:09 ` Gerd Hoffmann
2021-11-10 12:02 ` Michael S. Tsirkin
2021-11-11 7:53 ` Gerd Hoffmann
2021-11-11 8:20 ` Michael S. Tsirkin
2021-11-11 9:34 ` Gerd Hoffmann
2021-11-11 12:09 ` Gerd Hoffmann
2021-11-11 15:39 ` Michael S. Tsirkin
2021-11-12 11:15 ` Gerd Hoffmann
2021-11-12 12:17 ` Igor Mammedov [this message]
2021-11-15 11:13 ` Michael S. Tsirkin
2021-11-11 9:35 ` Daniel P. Berrangé
2021-11-11 17:11 ` Michael S. Tsirkin
2021-11-11 18:08 ` Daniel P. Berrangé
2021-11-11 18:43 ` Michael S. Tsirkin
2021-11-12 10:16 ` Gerd Hoffmann
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