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From:   Haiyang Zhang <haiyangz@microsoft.com>
To:     Wei Liu <wei.liu@kernel.org>
CC:     Dexuan Cui <decui@microsoft.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "kuba@kernel.org" <kuba@kernel.org>,
        KY Srinivasan <kys@microsoft.com>,
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Subject: RE: [PATCH net-next] net: mana: Add a driver for Microsoft Azure
 Network Adapter (MANA)
Thread-Topic: [PATCH net-next] net: mana: Add a driver for Microsoft Azure
 Network Adapter (MANA)
Thread-Index: AQHXKzvmwFT+jLn9hE+ope3TVVs2GqqpCiOAgAAUhFCAAAhhAIAAAeVA
Date:   Wed, 7 Apr 2021 15:16:54 +0000
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> -----Original Message-----
> From: Wei Liu <wei.liu@kernel.org>
> Sent: Wednesday, April 7, 2021 11:01 AM
> To: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Wei Liu <wei.liu@kernel.org>; Dexuan Cui <decui@microsoft.com>;
> davem@davemloft.net; kuba@kernel.org; KY Srinivasan
> <kys@microsoft.com>; Stephen Hemminger <sthemmin@microsoft.com>;
> Wei Liu <liuwe@microsoft.com>; netdev@vger.kernel.org; linux-
> kernel@vger.kernel.org; linux-hyperv@vger.kernel.org
> Subject: Re: [PATCH net-next] net: mana: Add a driver for Microsoft Azure
> Network Adapter (MANA)
>=20
> On Wed, Apr 07, 2021 at 02:34:01PM +0000, Haiyang Zhang wrote:
> >
> >
> > > -----Original Message-----
> > > From: Wei Liu <wei.liu@kernel.org>
> > > Sent: Wednesday, April 7, 2021 9:17 AM
> > > To: Dexuan Cui <decui@microsoft.com>
> > > Cc: davem@davemloft.net; kuba@kernel.org; KY Srinivasan
> > > <kys@microsoft.com>; Haiyang Zhang <haiyangz@microsoft.com>;
> Stephen
> > > Hemminger <sthemmin@microsoft.com>; wei.liu@kernel.org; Wei Liu
> > > <liuwe@microsoft.com>; netdev@vger.kernel.org; linux-
> > > kernel@vger.kernel.org; linux-hyperv@vger.kernel.org
> > > Subject: Re: [PATCH net-next] net: mana: Add a driver for Microsoft
> > > Azure Network Adapter (MANA)
> > >
> > > On Tue, Apr 06, 2021 at 04:23:21PM -0700, Dexuan Cui wrote:
> > > [...]
> > > > +config MICROSOFT_MANA
> > > > +	tristate "Microsoft Azure Network Adapter (MANA) support"
> > > > +	default m
> > > > +	depends on PCI_MSI
> > > > +	select PCI_HYPERV
> > >
> > > OOI which part of the code requires PCI_HYPERV?
> > >
> > > Asking because I can't immediately find code that looks to be
> > > Hyper-V specific (searching for vmbus etc). This device looks like
> > > any other PCI devices to me.
> >
> > It depends on the VF nic's PCI config space which is presented by the
> pci_hyperv driver.
>=20
> I think all it matters is the PCI bus is able to handle the configuration=
 space
> access, right? Assuming there is an emulated PCI root complex which
> exposes the config space to the driver, will this driver still work?
>=20
> I'm trying to understand how tightly coupled with Hyper-V PCI this driver=
 is.
> In an alternative universe, Microsft may suddenly decide to sell this
> hardware and someone wants to passthrough an VF via VFIO. I don't see
> how this driver wouldn't work, hence the original question.
>=20
> There is no need to change the code. I'm just curious about a tiny detail=
 in
> the implementation.

Currently, the PCI config space only comes from pci_hyperv, so we have this=
=20
dependency.

If the pci config space is presented from other ways in an "alternative uni=
verse",=20
we may need to add other dependencies. And yes, the VF should continue to w=
ork:)

Thanks,
- Haiyang