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[v6,0/8] PCI: hv: Support host bridge probing on ARM64

Message ID 20210726180657.142727-1-boqun.feng@gmail.com (mailing list archive)
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Series PCI: hv: Support host bridge probing on ARM64 | expand

Message

Boqun Feng July 26, 2021, 6:06 p.m. UTC
Hi,

This is the v6 for the preparation of virtual PCI support on Hyper-V
ARM64, Previous versions:

v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/

Changes since last version:

*	Rebase to 5.14-rc3

*	Comment fixes as suggested by Bjorn.

The basic problem we need to resolve is that ARM64 is an arch with
PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
Hyper-V PCI provides a paravirtualized PCI interface, so there is no
actual pci_config_window for a PCI host bridge, so no information can be
retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
there is no corresponding ACPI device for the Hyper-V PCI root bridge,
which introduces a special case when trying to find the ACPI device from
the sysdata (see patch #3).

With this patchset, we could enable the virtual PCI on Hyper-V ARM64
guest with other code under development.

Comments and suggestions are welcome.

Regards,
Boqun

Arnd Bergmann (1):
  PCI: hv: Generify PCI probing

Boqun Feng (7):
  PCI: Introduce domain_nr in pci_host_bridge
  PCI: Support populating MSI domains of root buses via bridges
  arm64: PCI: Restructure pcibios_root_bridge_prepare()
  arm64: PCI: Support root bridge preparation for Hyper-V
  PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
  PCI: hv: Set up MSI domain at bridge probing time
  PCI: hv: Turn on the host bridge probing on ARM64

 arch/arm64/kernel/pci.c             | 29 +++++++---
 drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
 drivers/pci/probe.c                 | 12 +++-
 include/linux/pci.h                 | 11 ++++
 4 files changed, 93 insertions(+), 45 deletions(-)

Comments

Bjorn Helgaas July 27, 2021, 4:12 p.m. UTC | #1
On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> Hi,
> 
> This is the v6 for the preparation of virtual PCI support on Hyper-V
> ARM64, Previous versions:
> 
> v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/

Thanks for these; they're very handy for archaeology later.

> Changes since last version:
> 
> *	Rebase to 5.14-rc3

Just FYI, it's not a problem that you rebased, but it's not necessary.
These will be applied to a topic branch from v5.14-rc1 anyway.
Boqun Feng Aug. 2, 2021, 8:13 a.m. UTC | #2
On Tue, Jul 27, 2021 at 11:12:59AM -0500, Bjorn Helgaas wrote:
> On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> > Hi,
> > 
> > This is the v6 for the preparation of virtual PCI support on Hyper-V
> > ARM64, Previous versions:
> > 
> > v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> > v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> > v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> > v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> > v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> 
> Thanks for these; they're very handy for archaeology later.
> 
> > Changes since last version:
> > 
> > *	Rebase to 5.14-rc3
> 
> Just FYI, it's not a problem that you rebased, but it's not necessary.
> These will be applied to a topic branch from v5.14-rc1 anyway.

Got it ;-)

Regards,
Boqun
Boqun Feng Aug. 2, 2021, 8:15 a.m. UTC | #3
On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> Hi,
> 
> This is the v6 for the preparation of virtual PCI support on Hyper-V
> ARM64, Previous versions:
> 
> v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> 
> Changes since last version:
> 
> *	Rebase to 5.14-rc3
> 
> *	Comment fixes as suggested by Bjorn.
> 
> The basic problem we need to resolve is that ARM64 is an arch with
> PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> actual pci_config_window for a PCI host bridge, so no information can be
> retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> which introduces a special case when trying to find the ACPI device from
> the sysdata (see patch #3).
> 
> With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> guest with other code under development.
> 
> Comments and suggestions are welcome.
> 

Ping ;-)

Regards,
Boqun

> Regards,
> Boqun
> 
> Arnd Bergmann (1):
>   PCI: hv: Generify PCI probing
> 
> Boqun Feng (7):
>   PCI: Introduce domain_nr in pci_host_bridge
>   PCI: Support populating MSI domains of root buses via bridges
>   arm64: PCI: Restructure pcibios_root_bridge_prepare()
>   arm64: PCI: Support root bridge preparation for Hyper-V
>   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
>   PCI: hv: Set up MSI domain at bridge probing time
>   PCI: hv: Turn on the host bridge probing on ARM64
> 
>  arch/arm64/kernel/pci.c             | 29 +++++++---
>  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
>  drivers/pci/probe.c                 | 12 +++-
>  include/linux/pci.h                 | 11 ++++
>  4 files changed, 93 insertions(+), 45 deletions(-)
> 
> -- 
> 2.32.0
>
Bjorn Helgaas Aug. 2, 2021, 11:05 p.m. UTC | #4
On Mon, Aug 02, 2021 at 04:15:04PM +0800, Boqun Feng wrote:
> On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> > Hi,
> > 
> > This is the v6 for the preparation of virtual PCI support on Hyper-V
> > ARM64, Previous versions:
> > 
> > v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> > v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> > v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> > v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> > v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> > 
> > Changes since last version:
> > 
> > *	Rebase to 5.14-rc3
> > 
> > *	Comment fixes as suggested by Bjorn.
> > 
> > The basic problem we need to resolve is that ARM64 is an arch with
> > PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> > Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> > actual pci_config_window for a PCI host bridge, so no information can be
> > retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> > there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> > which introduces a special case when trying to find the ACPI device from
> > the sysdata (see patch #3).
> > 
> > With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> > guest with other code under development.
> > 
> > Comments and suggestions are welcome.
> 
> Ping ;-)

Lorenzo normally takes care of the native drivers (including Hyper-V),
so I don't want to get in his way.  If he's too busy and doesn't get a
chance, poke me again after -rc6 or so and I'll pick it up.

> > Arnd Bergmann (1):
> >   PCI: hv: Generify PCI probing
> > 
> > Boqun Feng (7):
> >   PCI: Introduce domain_nr in pci_host_bridge
> >   PCI: Support populating MSI domains of root buses via bridges
> >   arm64: PCI: Restructure pcibios_root_bridge_prepare()
> >   arm64: PCI: Support root bridge preparation for Hyper-V
> >   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
> >   PCI: hv: Set up MSI domain at bridge probing time
> >   PCI: hv: Turn on the host bridge probing on ARM64
> > 
> >  arch/arm64/kernel/pci.c             | 29 +++++++---
> >  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
> >  drivers/pci/probe.c                 | 12 +++-
> >  include/linux/pci.h                 | 11 ++++
> >  4 files changed, 93 insertions(+), 45 deletions(-)
> > 
> > -- 
> > 2.32.0
> >
Lorenzo Pieralisi Aug. 19, 2021, 2:17 p.m. UTC | #5
On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> Hi,
> 
> This is the v6 for the preparation of virtual PCI support on Hyper-V
> ARM64, Previous versions:
> 
> v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> 
> Changes since last version:
> 
> *	Rebase to 5.14-rc3
> 
> *	Comment fixes as suggested by Bjorn.
> 
> The basic problem we need to resolve is that ARM64 is an arch with
> PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> actual pci_config_window for a PCI host bridge, so no information can be
> retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> which introduces a special case when trying to find the ACPI device from
> the sysdata (see patch #3).
> 
> With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> guest with other code under development.
> 
> Comments and suggestions are welcome.
> 
> Regards,
> Boqun
> 
> Arnd Bergmann (1):
>   PCI: hv: Generify PCI probing
> 
> Boqun Feng (7):
>   PCI: Introduce domain_nr in pci_host_bridge
>   PCI: Support populating MSI domains of root buses via bridges
>   arm64: PCI: Restructure pcibios_root_bridge_prepare()
>   arm64: PCI: Support root bridge preparation for Hyper-V
>   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
>   PCI: hv: Set up MSI domain at bridge probing time
>   PCI: hv: Turn on the host bridge probing on ARM64
> 
>  arch/arm64/kernel/pci.c             | 29 +++++++---
>  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
>  drivers/pci/probe.c                 | 12 +++-
>  include/linux/pci.h                 | 11 ++++
>  4 files changed, 93 insertions(+), 45 deletions(-)

If we take this series via the PCI tree we'd need Catalin/Will ACKs on
patches 3-4.

I need some time to look into [1] (thanks for that).

Without [1] patch 8 is ugly, that's no news. The question is whether
it is worth waiting for a kernel cycle to integrate [1] into this series
or not.

Is it really a problem if we postpone this series for another kernel
cycle so that we can look into it ?

[1] https://lore.kernel.org/lkml/20210811153619.88922-1-boqun.feng@gmail.com/
Boqun Feng Aug. 19, 2021, 3:47 p.m. UTC | #6
On Thu, Aug 19, 2021 at 03:17:58PM +0100, Lorenzo Pieralisi wrote:
> On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> > Hi,
> > 
> > This is the v6 for the preparation of virtual PCI support on Hyper-V
> > ARM64, Previous versions:
> > 
> > v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> > v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> > v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> > v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> > v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> > 
> > Changes since last version:
> > 
> > *	Rebase to 5.14-rc3
> > 
> > *	Comment fixes as suggested by Bjorn.
> > 
> > The basic problem we need to resolve is that ARM64 is an arch with
> > PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> > Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> > actual pci_config_window for a PCI host bridge, so no information can be
> > retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> > there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> > which introduces a special case when trying to find the ACPI device from
> > the sysdata (see patch #3).
> > 
> > With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> > guest with other code under development.
> > 
> > Comments and suggestions are welcome.
> > 
> > Regards,
> > Boqun
> > 
> > Arnd Bergmann (1):
> >   PCI: hv: Generify PCI probing
> > 
> > Boqun Feng (7):
> >   PCI: Introduce domain_nr in pci_host_bridge
> >   PCI: Support populating MSI domains of root buses via bridges
> >   arm64: PCI: Restructure pcibios_root_bridge_prepare()
> >   arm64: PCI: Support root bridge preparation for Hyper-V
> >   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
> >   PCI: hv: Set up MSI domain at bridge probing time
> >   PCI: hv: Turn on the host bridge probing on ARM64
> > 
> >  arch/arm64/kernel/pci.c             | 29 +++++++---
> >  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
> >  drivers/pci/probe.c                 | 12 +++-
> >  include/linux/pci.h                 | 11 ++++
> >  4 files changed, 93 insertions(+), 45 deletions(-)
> 
> If we take this series via the PCI tree we'd need Catalin/Will ACKs on
> patches 3-4.
> 

Got it.

> I need some time to look into [1] (thanks for that).
> 
> Without [1] patch 8 is ugly, that's no news. The question is whether
> it is worth waiting for a kernel cycle to integrate [1] into this series
> or not.
> 
> Is it really a problem if we postpone this series for another kernel
> cycle so that we can look into it ?
> 

Well, it's definitely better for me that we can have it in 5.15-rc1 ;-),
because it's a dependency for Hyper-V virtual PCI support on ARM64 and
we plan to send the rest of work in 5.15 cycle. And I can just base on
hyperv-next for the rest of the work if this is in 5.15-rc1. But yes,
it's not really a problem, since this one still needs to work with other
patches to support virtual PCI on ARM64 Hyper-V.

In fact, I personally don't think [1] is better than patch 8 (plus patch
3 & 4): playing with ->private seems dangerous and not very helpful on
readiblity, but I agree that we should explore every potential solution,
and that's why I send [1].

Regards,
Boqun

> [1] https://lore.kernel.org/lkml/20210811153619.88922-1-boqun.feng@gmail.com/
Lorenzo Pieralisi Aug. 23, 2021, 10:02 a.m. UTC | #7
On Tue, 27 Jul 2021 02:06:49 +0800, Boqun Feng wrote:
> This is the v6 for the preparation of virtual PCI support on Hyper-V
> ARM64, Previous versions:
> 
> v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> 
> [...]

Applied to pci/hyper-v, thanks!

[1/8] PCI: Introduce domain_nr in pci_host_bridge
      https://git.kernel.org/lpieralisi/pci/c/15d82ca23c
[2/8] PCI: Support populating MSI domains of root buses via bridges
      https://git.kernel.org/lpieralisi/pci/c/41dd40fd71
[3/8] arm64: PCI: Restructure pcibios_root_bridge_prepare()
      https://git.kernel.org/lpieralisi/pci/c/b424d4d426
[4/8] arm64: PCI: Support root bridge preparation for Hyper-V
      https://git.kernel.org/lpieralisi/pci/c/7d40c0f70d
[5/8] PCI: hv: Generify PCI probing
      https://git.kernel.org/lpieralisi/pci/c/418cb6c8e0
[6/8] PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
      https://git.kernel.org/lpieralisi/pci/c/38c0d266dc
[7/8] PCI: hv: Set up MSI domain at bridge probing time
      https://git.kernel.org/lpieralisi/pci/c/9e7f9178ab
[8/8] PCI: hv: Turn on the host bridge probing on ARM64
      https://git.kernel.org/lpieralisi/pci/c/88f94c7f8f

Thanks,
Lorenzo
Lorenzo Pieralisi Aug. 23, 2021, 10:10 a.m. UTC | #8
On Thu, Aug 19, 2021 at 11:47:52PM +0800, Boqun Feng wrote:
> On Thu, Aug 19, 2021 at 03:17:58PM +0100, Lorenzo Pieralisi wrote:
> > On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> > > Hi,
> > > 
> > > This is the v6 for the preparation of virtual PCI support on Hyper-V
> > > ARM64, Previous versions:
> > > 
> > > v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> > > v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> > > v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> > > v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> > > v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> > > 
> > > Changes since last version:
> > > 
> > > *	Rebase to 5.14-rc3
> > > 
> > > *	Comment fixes as suggested by Bjorn.
> > > 
> > > The basic problem we need to resolve is that ARM64 is an arch with
> > > PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> > > Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> > > actual pci_config_window for a PCI host bridge, so no information can be
> > > retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> > > there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> > > which introduces a special case when trying to find the ACPI device from
> > > the sysdata (see patch #3).
> > > 
> > > With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> > > guest with other code under development.
> > > 
> > > Comments and suggestions are welcome.
> > > 
> > > Regards,
> > > Boqun
> > > 
> > > Arnd Bergmann (1):
> > >   PCI: hv: Generify PCI probing
> > > 
> > > Boqun Feng (7):
> > >   PCI: Introduce domain_nr in pci_host_bridge
> > >   PCI: Support populating MSI domains of root buses via bridges
> > >   arm64: PCI: Restructure pcibios_root_bridge_prepare()
> > >   arm64: PCI: Support root bridge preparation for Hyper-V
> > >   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
> > >   PCI: hv: Set up MSI domain at bridge probing time
> > >   PCI: hv: Turn on the host bridge probing on ARM64
> > > 
> > >  arch/arm64/kernel/pci.c             | 29 +++++++---
> > >  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
> > >  drivers/pci/probe.c                 | 12 +++-
> > >  include/linux/pci.h                 | 11 ++++
> > >  4 files changed, 93 insertions(+), 45 deletions(-)
> > 
> > If we take this series via the PCI tree we'd need Catalin/Will ACKs on
> > patches 3-4.
> > 
> 
> Got it.
> 
> > I need some time to look into [1] (thanks for that).
> > 
> > Without [1] patch 8 is ugly, that's no news. The question is whether
> > it is worth waiting for a kernel cycle to integrate [1] into this series
> > or not.
> > 
> > Is it really a problem if we postpone this series for another kernel
> > cycle so that we can look into it ?
> > 
> 
> Well, it's definitely better for me that we can have it in 5.15-rc1 ;-),
> because it's a dependency for Hyper-V virtual PCI support on ARM64 and
> we plan to send the rest of work in 5.15 cycle. And I can just base on
> hyperv-next for the rest of the work if this is in 5.15-rc1. But yes,
> it's not really a problem, since this one still needs to work with other
> patches to support virtual PCI on ARM64 Hyper-V.
> 
> In fact, I personally don't think [1] is better than patch 8 (plus patch
> 3 & 4): playing with ->private seems dangerous and not very helpful on
> readiblity, but I agree that we should explore every potential solution,
> and that's why I send [1].

Pulled the current series - now let's work together to improve it, I
will have a look into [1] in the weeks to come and get back to you with
some feedback.

Thanks,
Lorenzo

> Regards,
> Boqun
> 
> > [1] https://lore.kernel.org/lkml/20210811153619.88922-1-boqun.feng@gmail.com/
Boqun Feng Aug. 23, 2021, 12:49 p.m. UTC | #9
On Mon, Aug 23, 2021 at 11:10:00AM +0100, Lorenzo Pieralisi wrote:
> On Thu, Aug 19, 2021 at 11:47:52PM +0800, Boqun Feng wrote:
> > On Thu, Aug 19, 2021 at 03:17:58PM +0100, Lorenzo Pieralisi wrote:
> > > On Tue, Jul 27, 2021 at 02:06:49AM +0800, Boqun Feng wrote:
> > > > Hi,
> > > > 
> > > > This is the v6 for the preparation of virtual PCI support on Hyper-V
> > > > ARM64, Previous versions:
> > > > 
> > > > v1:	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/
> > > > v2:	https://lore.kernel.org/lkml/20210503144635.2297386-1-boqun.feng@gmail.com/
> > > > v3:	https://lore.kernel.org/lkml/20210609163211.3467449-1-boqun.feng@gmail.com/
> > > > v4:	https://lore.kernel.org/lkml/20210714102737.198432-1-boqun.feng@gmail.com/
> > > > v5:	https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
> > > > 
> > > > Changes since last version:
> > > > 
> > > > *	Rebase to 5.14-rc3
> > > > 
> > > > *	Comment fixes as suggested by Bjorn.
> > > > 
> > > > The basic problem we need to resolve is that ARM64 is an arch with
> > > > PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
> > > > Hyper-V PCI provides a paravirtualized PCI interface, so there is no
> > > > actual pci_config_window for a PCI host bridge, so no information can be
> > > > retrieve from the pci_config_window of a Hyper-V virtual PCI bus. Also
> > > > there is no corresponding ACPI device for the Hyper-V PCI root bridge,
> > > > which introduces a special case when trying to find the ACPI device from
> > > > the sysdata (see patch #3).
> > > > 
> > > > With this patchset, we could enable the virtual PCI on Hyper-V ARM64
> > > > guest with other code under development.
> > > > 
> > > > Comments and suggestions are welcome.
> > > > 
> > > > Regards,
> > > > Boqun
> > > > 
> > > > Arnd Bergmann (1):
> > > >   PCI: hv: Generify PCI probing
> > > > 
> > > > Boqun Feng (7):
> > > >   PCI: Introduce domain_nr in pci_host_bridge
> > > >   PCI: Support populating MSI domains of root buses via bridges
> > > >   arm64: PCI: Restructure pcibios_root_bridge_prepare()
> > > >   arm64: PCI: Support root bridge preparation for Hyper-V
> > > >   PCI: hv: Set ->domain_nr of pci_host_bridge at probing time
> > > >   PCI: hv: Set up MSI domain at bridge probing time
> > > >   PCI: hv: Turn on the host bridge probing on ARM64
> > > > 
> > > >  arch/arm64/kernel/pci.c             | 29 +++++++---
> > > >  drivers/pci/controller/pci-hyperv.c | 86 +++++++++++++++++------------
> > > >  drivers/pci/probe.c                 | 12 +++-
> > > >  include/linux/pci.h                 | 11 ++++
> > > >  4 files changed, 93 insertions(+), 45 deletions(-)
> > > 
> > > If we take this series via the PCI tree we'd need Catalin/Will ACKs on
> > > patches 3-4.
> > > 
> > 
> > Got it.
> > 
> > > I need some time to look into [1] (thanks for that).
> > > 
> > > Without [1] patch 8 is ugly, that's no news. The question is whether
> > > it is worth waiting for a kernel cycle to integrate [1] into this series
> > > or not.
> > > 
> > > Is it really a problem if we postpone this series for another kernel
> > > cycle so that we can look into it ?
> > > 
> > 
> > Well, it's definitely better for me that we can have it in 5.15-rc1 ;-),
> > because it's a dependency for Hyper-V virtual PCI support on ARM64 and
> > we plan to send the rest of work in 5.15 cycle. And I can just base on
> > hyperv-next for the rest of the work if this is in 5.15-rc1. But yes,
> > it's not really a problem, since this one still needs to work with other
> > patches to support virtual PCI on ARM64 Hyper-V.
> > 
> > In fact, I personally don't think [1] is better than patch 8 (plus patch
> > 3 & 4): playing with ->private seems dangerous and not very helpful on
> > readiblity, but I agree that we should explore every potential solution,
> > and that's why I send [1].
> 
> Pulled the current series - now let's work together to improve it, I
> will have a look into [1] in the weeks to come and get back to you with
> some feedback.
> 

Thanks a lot! Looking forwards to your feedback ;-)

Regards,
Boqun

> Thanks,
> Lorenzo
> 
> > Regards,
> > Boqun
> > 
> > > [1] https://lore.kernel.org/lkml/20210811153619.88922-1-boqun.feng@gmail.com/