netdev - Re: [pci PATCH v4 1/4] pci-iov: Add support for unmanaged SR-IOV

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Message-ID: <20180311215909.16ed4bf1@t450s.home>
Date:   Sun, 11 Mar 2018 21:59:09 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     bhelgaas@...gle.com, alexander.h.duyck@...el.com,
        linux-pci@...r.kernel.org, virtio-dev@...ts.oasis-open.org,
        kvm@...r.kernel.org, netdev@...r.kernel.org, dan.daly@...el.com,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        keith.busch@...el.com, netanel@...zon.com, mheyne@...zon.de,
        liang-min.wang@...el.com, mark.d.rustad@...el.com,
        dwmw2@...radead.org, hch@....de, dwmw@...zon.co.uk
Subject: Re: [pci PATCH v4 1/4] pci-iov: Add support for unmanaged SR-IOV

On Thu, 08 Mar 2018 11:02:29 -0800
Alexander Duyck <alexander.duyck@...il.com> wrote:

> From: Alexander Duyck <alexander.h.duyck@...el.com>
> 
> This patch is meant to add some basic functionality to support for SR-IOV
> on devices when the VFs are not managed by some other entity in the device
> other than the kernel.
> 
> A new sysfs value called sriov_unmanaged_autoprobe has been added. This
> value is used as the drivers_autoprobe setting of the VFs when they are
> being managed by an external entity such as device firmware instead of
> being managed by the kernel.
> 
> One side effect of this change is that the sriov_drivers_autoprobe and
> sriov_unmanaged_autoprobe will only apply their updates when SR-IOV VFs
> are allocated. Attempts to update them when SR-IOV is in use will only
> update the local value and will not update sriov->autoprobe.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---


I still struggle to understand why we need this "unmanaged"
complication and how a user of the sysfs API is expected to have any
idea whether a PF is managed or unmanaged and why they should care.
Can't we just have a pci_simple_sriov_configure() helper and ignore
this unmanaged business?  Thanks,

Alex