Re: [RFC v3 0/7] PCI: hv: Support host bridge probing on ARM64

From: Marc Zyngier <maz@misterjones.org>
To: Ard Biesheuvel <ardb@kernel.org>, Boqun Feng <boqun.feng@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-hyperv@vger.kernel.org, PCI <linux-pci@vger.kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Rob Herring <robh@kernel.org>, Clint Sbisa <csbisa@amazon.com>,
	Sunil Muthuswamy <sunilmut@microsoft.com>
Subject: Re: [RFC v3 0/7] PCI: hv: Support host bridge probing on ARM64
Date: Thu, 10 Jun 2021 16:42:45 +0100	[thread overview]
Message-ID: <2283b22ae7832db348bd9b3eff3aab16@misterjones.org> (raw)
In-Reply-To: <CAMj1kXGwa28T5Cr_64OC4rqE3qhwWQz+BJPwjdr54G-pVf9+pA@mail.gmail.com>

On 2021-06-10 16:01, Ard Biesheuvel wrote:
> On Wed, 9 Jun 2021 at 18:32, Boqun Feng <boqun.feng@gmail.com> wrote:
>> 
>> Hi Bjorn, Arnd and Marc,
>> 
> 
> Instead of cc'ing Arnd, you cc'ed me (Ard)

And I don't know if you intended to Cc me, but you definitely didn't.

Thanks,

         M.

> 
>> This is the v3 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/
>> 
>> Changes since last version:
>> 
>> *       Use a sentinel value approach instead of calling
>>         pci_bus_find_domain_nr() for every CONFIG_PCI_DOMAIN_GENERIC=y
>>         arch as per suggestion from
>> 
>> *       Improve the commit log and comments for patch #6.
>> 
>> *       Rebase to the latest mainline.
>> 
>> 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.
>> 
>> 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 (6):
>>   PCI: Introduce domain_nr in pci_host_bridge
>>   PCI: Allow msi domain set-up at host probing time
>>   PCI: hv: Use pci_host_bridge::domain_nr for PCI domain
>>   PCI: hv: Set up msi domain at bridge probing time
>>   arm64: PCI: Support root bridge preparation for Hyper-V PCI
>>   PCI: hv: Turn on the host bridge probing on ARM64
>> 
>>  arch/arm64/kernel/pci.c             |  7 ++-
>>  drivers/pci/controller/pci-hyperv.c | 87 
>> +++++++++++++++++------------
>>  drivers/pci/probe.c                 |  9 ++-
>>  include/linux/pci.h                 | 10 ++++
>>  4 files changed, 73 insertions(+), 40 deletions(-)
>> 
>> --
>> 2.30.2
>> 
> 
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