Date:   Tue, 24 Apr 2018 16:51:50 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Alexander Duyck <alexander.h.duyck@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        virtio-dev@...ts.oasis-open.org, kvm@...r.kernel.org,
        Netdev <netdev@...r.kernel.org>,
        "Daly, Dan" <dan.daly@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-nvme@...ts.infradead.org,
        Keith Busch <keith.busch@...el.com>, netanel@...zon.com,
        Don Dutile <ddutile@...hat.com>,
        Maximilian Heyne <mheyne@...zon.de>,
        "Wang, Liang-min" <liang-min.wang@...el.com>,
        "Rustad, Mark D" <mark.d.rustad@...el.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Christoph Hellwig <hch@....de>, dwmw@...zon.co.uk
Subject: Re: [pci PATCH v8 0/4] Add support for unmanaged SR-IOV

On Sat, Apr 21, 2018 at 05:22:27PM -0700, Alexander Duyck wrote:
> On Sat, Apr 21, 2018 at 1:34 PM, Bjorn Helgaas <helgaas@...nel.org> wrote:

> > For example, I'm not sure what you mean by "devices where the PF is
> > not capable of managing VF resources."
> >
> > It *sounds* like you're saying the hardware works differently on some
> > devices, but I don't think that's what you mean.  I think you're
> > saying something about which drivers are used for the PF and the VF.
> 
> That is sort of what I am saying.
> 
> So for example with ixgbe there is functionality which is controlled
> in the MMIO space of the PF that affects the functionality of the VFs
> that are generated on the device. The PF has to rearrange the
> resources such as queues and interrupts on the device before it can
> enable SR-IOV, and it could alter those later to limit what the VF is
> capable of doing.
> 
> The model I am dealing with via this patch set has a PF that is not
> much different than the VFs other than the fact that it has some
> extended configuration space bits in place for SR-IOV, ARI, ACS, and
> whatever other bits are needed in order to support spawning isolated
> VFs.

OK, thanks for the explanation, I think I understand what's going on
now, correct me if I'm mistaken.  I added a hint about "PF" for Randy,
too.

These are on pci/virtualization for v4.18.


commit 8effc395c209
Author: Alexander Duyck <alexander.h.duyck@...el.com>
Date:   Sat Apr 21 15:23:09 2018 -0500

    PCI/IOV: Add pci_sriov_configure_simple()
    
    SR-IOV (Single Root I/O Virtualization) is an optional PCIe capability (see
    PCIe r4.0, sec 9).  A PCIe Function with the SR-IOV capability is referred
    to as a PF (Physical Function).  If SR-IOV is enabled on the PF, several
    VFs (Virtual Functions) may be created.  The VFs can be individually
    assigned to virtual machines, which allows them to share a single hardware
    device while being isolated from each other.
    
    Some SR-IOV devices have resources such as queues and interrupts that must
    be set up in the PF before enabling the VFs, so they require a PF driver to
    do that.
    
    Other SR-IOV devices don't require any PF setup before enabling VFs.  Add a
    pci_sriov_configure_simple() interface so PF drivers for such devices can
    use it without repeating the VF-enabling code.
    
    Tested-by: Mark Rustad <mark.d.rustad@...el.com>
    Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
    [bhelgaas: changelog, comment]
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
    Reviewed-by: Greg Rose <gvrose8192@...il.com>
    Reviewed-by: Christoph Hellwig <hch@....de>:wq

commit a8ccf8a66663
Author: Alexander Duyck <alexander.h.duyck@...el.com>
Date:   Tue Apr 24 16:47:16 2018 -0500

    PCI/IOV: Add pci-pf-stub driver for PFs that only enable VFs
    
    Some SR-IOV PF devices provide no functionality other than acting as a
    means of enabling VFs.  For these devices, we want to enable the VFs and
    assign them to guest virtual machines, but there's no need to have a driver
    for the PF itself.
    
    Add a new pci-pf-stub driver to claim those PF devices and provide the
    generic VF enable functionality.  An administrator can use the sysfs
    "sriov_numvfs" file to enable VFs, then assign them to guests.
    
    For now I only have one example ID provided by Amazon in terms of devices
    that require this functionality.  The general idea is that in the future we
    will see other devices added as vendors come up with devices where the PF
    is more or less just a lightweight shim used to allocate VFs.
    
    Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
    [bhelgaas: changelog]
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
    Reviewed-by: Greg Rose <gvrose8192@...il.com>
    Reviewed-by: Christoph Hellwig <hch@....de>

commit 115ddc491922
Author: Alexander Duyck <alexander.h.duyck@...el.com>
Date:   Tue Apr 24 16:47:22 2018 -0500

    net: ena: Use pci_sriov_configure_simple() to enable VFs
    
    Instead of implementing our own version of a SR-IOV configuration stub in
    the ena driver, use the existing pci_sriov_configure_simple() function.
    
    Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
    Reviewed-by: Greg Rose <gvrose8192@...il.com>
    Reviewed-by: Christoph Hellwig <hch@....de>

commit 74d986abc20b
Author: Alexander Duyck <alexander.h.duyck@...el.com>
Date:   Tue Apr 24 16:47:27 2018 -0500

    nvme-pci: Use pci_sriov_configure_simple() to enable VFs
    
    Instead of implementing our own version of a SR-IOV configuration stub in
    the nvme driver, use the existing pci_sriov_configure_simple() function.
    
    Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
    Reviewed-by: Christoph Hellwig <hch@....de>

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