From: Cornelia Huck <cohuck@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "Damien Hedde" <damien.hedde@greensocs.com>,
"Daniel P. Berrange" <berrange@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
qemu-s390x <qemu-s390x@nongnu.org>,
"Mark Burton" <mark.burton@greensocs.com>,
"QEMU Developers" <qemu-devel@nongnu.org>,
"Edgar Iglesias" <edgari@xilinx.com>,
qemu-arm <qemu-arm@nongnu.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: [PATCH v5 06/13] hw/core/qdev: handle parent bus change regarding resettable
Date: Tue, 3 Dec 2019 12:37:14 +0100 [thread overview]
Message-ID: <20191203123714.0886e34f.cohuck@redhat.com> (raw)
In-Reply-To: <CAFEAcA981i_W=8y+7_8JV=oMLT51TBMB8bTJJaiJJZqj6MuSAQ@mail.gmail.com>
On Fri, 29 Nov 2019 18:41:26 +0000
Peter Maydell <peter.maydell@linaro.org> wrote:
> On Fri, 18 Oct 2019 at 16:07, Damien Hedde <damien.hedde@greensocs.com> wrote:
> >
> > In qdev_set_parent_bus(), when changing the parent bus of a
> > realized device, if the source and destination buses are not in the
> > same reset state, some adaptation are required. This patch adds
>
> "adaptations"
>
> > needed call to resettable_change_parent() to make sure a device reset
> > state stays coherent with its parent bus.
> >
> > The addition is a no-op if:
> > 1. the device being parented is not realized.
> > 2. the device is realized, but both buses are not under reset.
> >
> > Case 2 means that as long as qdev_set_parent_bus() is called
> > during the machine realization procedure (which is before the
> > machine reset so nothing is in reset), it is a no op.
> >
> > There are 49 call sites of qdev_set_parent_bus(). All but one fall
> > into the no-op case:
> > + 28 calls related to virtio (in hw/{s390x,display,virtio}/
> > {vhost,virtio}-xxx.c) to set a _vdev_/_vgpu_ composing device
> > parent bus just before realizing the _vdev_/_vgpu_.
> > + hw/qdev.c: when creating a device in qdev_try_create()
> > + hw/sysbus.c: when initializing a device in the sysbus
> > + hw/display/virtio-gpu-pci.c: before realizing VirtIOGPUPCIBase/vgpu
> > + hw/display/virtio-vga.c: before realizing VirtIOVGABase/vgpu
> > + hw/i386/amd_iommu.c: before realizing AMDVIState/pci
> > + hw/misc/auxbus.c: when creating an AUXBus
> > + hw/misc/auxbus.c: when creating an AUXBus child
> > + hw/misc/macio/macio.c: when initializing a MACIOState child
> > + hw/misc/macio/macio.c: before realizing NewWorldMacIOState/pmu
> > + hw/misc/macio/macio.c: before realizing NewWorldMacIOState/cuda
> > + hw/pci-host/designware.c: before realizing DesignwarePCIEHost/root
> > + hw/pci-host/gpex.c: before realizing GPEXHost/root
> > + hw/pci-host/prep.c: when initializaing PREPPCIState/pci_dev
> > + hw/pci-host/q35.c: before realizing Q35PCIHost/mch
> > + hw/pci-host/versatile.c: when initializing PCIVPBState/pci_dev
> > + hw/pci-host/xilinx-pcie.c: before realizing XilinxPCIEHost/root
> > + hw/s390x/event-facility.c: when creating SCLPEventFacility/
> > TYPE_SCLP_QUIESCE
> > + hw/s390x/event-facility.c: ditto with SCLPEventFacility/
> > TYPE_SCLP_CPU_HOTPLUG
> > + hw/s390x/sclp.c: Not trivial because it is called on a SLCPDevice
> > just after realizing it. Ok because at this point the destination
> > bus (sysbus) is not in reset; the realize step is before the
> > machine reset.
> > + hw/sd/core.c: Not OK. Used in sdbus_reparent_card(). See below.
> > + hw/ssi/ssi.c: Used to put spi slave on spi bus and connect the cs
> > line in ssi_auto_connect_slave(). Ok because this function is only
> > used in realize step in hw/ssi/aspeed_smc.ci, hw/ssi/imx_spi.c,
> > hw/ssi/mss-spi.c, hw/ssi/xilinx_spi.c and hw/ssi/xilinx_spips.c.
> > + hw/xen/xen-legacy-backend.c: when creating a XenLegacyDevice device
> > + qdev-monitor.c: in device hotplug creation procedure before realize
>
> This is a really useful analysis to have in the commit message;
> thanks!
>
> (Side note: I wonder if the sclp.c case could be reordered so
> it realizes the device after parenting it? Anyway, not something
> to worry about now.)
As far as I can see, that should work. This code is a bit weird anyway;
the problem is that we need the sysbus somewhere in there... I'm
wondering if that can be handled in a different way. But agreed, that
is something we can revisit later.
>
> > Note that this commit alone will have no effect, right now there is no
> > use of resettable API to reset anything. So a bus will never be tagged
> > as in-reset by this same API.
> >
> > The one place where side-effect will occurs is in hw/sd/core.c in
> > sdbus_reparent_card(). This function is only used in the raspi machines,
> > including during the sysbus reset procedure. This case will be fixed by
> > a following commit before globally enabling resettable API for sysbus
> > reset.
> >
> > Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> thanks
> -- PMM
>
next prev parent reply other threads:[~2019-12-03 11:39 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 15:06 [PATCH v5 00/13] Multi-phase reset mechanism Damien Hedde
2019-10-18 15:06 ` [PATCH v5 01/13] add device_legacy_reset function to prepare for reset api change Damien Hedde
2019-10-19 17:35 ` Richard Henderson
2019-12-03 10:55 ` Cornelia Huck
2019-10-18 15:06 ` [PATCH v5 02/13] hw/core/qdev: add trace events to help with resettable transition Damien Hedde
2019-10-19 17:44 ` Richard Henderson
2019-10-31 23:23 ` Philippe Mathieu-Daudé
2019-11-04 12:16 ` Damien Hedde
2019-11-04 14:33 ` Philippe Mathieu-Daudé
2019-12-03 10:57 ` Cornelia Huck
2019-10-18 15:06 ` [PATCH v5 03/13] hw/core: create Resettable QOM interface Damien Hedde
2019-11-29 18:32 ` Peter Maydell
2019-12-02 11:07 ` Damien Hedde
2019-12-02 11:14 ` Peter Maydell
2019-12-03 11:16 ` Cornelia Huck
2019-10-18 15:06 ` [PATCH v5 04/13] hw/core: add Resettable support to BusClass and DeviceClass Damien Hedde
2019-10-19 18:49 ` Richard Henderson
2019-11-29 18:36 ` Peter Maydell
2019-12-02 11:38 ` Damien Hedde
2019-10-18 15:06 ` [PATCH v5 05/13] hw/core/resettable: add support for changing parent Damien Hedde
2019-11-29 18:38 ` Peter Maydell
2019-12-02 11:43 ` Damien Hedde
2019-10-18 15:06 ` [PATCH v5 06/13] hw/core/qdev: handle parent bus change regarding resettable Damien Hedde
2019-11-29 18:41 ` Peter Maydell
2019-12-03 11:37 ` Cornelia Huck [this message]
2019-10-18 15:06 ` [PATCH v5 07/13] hw/core/qdev: update hotplug reset " Damien Hedde
2019-11-08 15:14 ` Damien Hedde
2019-10-18 15:06 ` [PATCH v5 08/13] hw/core: deprecate old reset functions and introduce new ones Damien Hedde
2019-10-31 23:35 ` Philippe Mathieu-Daudé
2019-11-04 12:01 ` Damien Hedde
2019-11-04 15:42 ` Philippe Mathieu-Daudé
2019-11-29 18:42 ` Peter Maydell
2019-10-18 15:06 ` [PATCH v5 09/13] docs/devel/reset.txt: add doc about Resettable interface Damien Hedde
2019-11-29 19:00 ` Peter Maydell
2019-12-06 15:40 ` Damien Hedde
2019-12-06 16:21 ` Damien Hedde
2019-10-18 15:06 ` [PATCH v5 10/13] vl: replace deprecated qbus_reset_all registration Damien Hedde
2019-11-29 19:01 ` Peter Maydell
2019-10-18 15:06 ` [PATCH v5 11/13] hw/s390x/ipl: replace deprecated qdev_reset_all registration Damien Hedde
2019-10-31 23:38 ` Philippe Mathieu-Daudé
2019-11-29 19:02 ` Peter Maydell
2019-12-03 11:41 ` Cornelia Huck
2019-10-18 15:06 ` [PATCH v5 12/13] hw/gpio/bcm2835_gpio: Isolate sdbus reparenting Damien Hedde
2019-11-29 19:05 ` Peter Maydell
2019-12-02 12:27 ` Damien Hedde
2019-12-02 12:33 ` Peter Maydell
2019-12-02 13:05 ` Damien Hedde
2019-12-02 13:10 ` Peter Maydell
2019-10-18 15:06 ` [PATCH v5 13/13] hw/gpio/bcm2835_gpio: Update to resettable Damien Hedde
2019-11-29 19:02 ` Peter Maydell
2019-10-19 9:01 ` [PATCH v5 00/13] Multi-phase reset mechanism no-reply
2019-10-29 15:53 ` Damien Hedde
2019-11-08 15:26 ` Damien Hedde
2019-11-08 15:28 ` Peter Maydell
2019-11-08 15:58 ` Damien Hedde
2019-11-29 19:07 ` Peter Maydell
2019-12-03 11:44 ` Cornelia Huck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191203123714.0886e34f.cohuck@redhat.com \
--to=cohuck@redhat.com \
--cc=berrange@redhat.com \
--cc=damien.hedde@greensocs.com \
--cc=david@gibson.dropbear.id.au \
--cc=edgari@xilinx.com \
--cc=ehabkost@redhat.com \
--cc=mark.burton@greensocs.com \
--cc=pbonzini@redhat.com \
--cc=peter.maydell@linaro.org \
--cc=philmd@redhat.com \
--cc=qemu-arm@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=qemu-s390x@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).