From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] PCI: allow drivers to limit the number of VFs to 0
Date: Fri, 30 Mar 2018 04:49:05 -0700
Message-ID: <20180330114905.GA10246@infradead.org>
References: <20180329182231.32151-1-jakub.kicinski@netronome.com>
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Cc: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org,
        netdev@vger.kernel.org, Sathya Perla <sathya.perla@broadcom.com>,
        Felix Manlunas <felix.manlunas@caviumnetworks.com>,
        alexander.duyck@gmail.com, john.fastabend@gmail.com,
        Jacob Keller <jacob.e.keller@intel.com>,
        Donald Dutile <ddutile@redhat.com>, oss-drivers@netronome.com
To: Jakub Kicinski <jakub.kicinski@netronome.com>
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On Thu, Mar 29, 2018 at 11:22:31AM -0700, Jakub Kicinski wrote:
> Some user space depends on driver allowing sriov_totalvfs to be
> enabled.

I can't make sene of this sentence.  Can you explain what user space
code depends on what semantics?  The sriov_totalvfs file should show
up for any device supporting SR-IOV as far as I can tell.

>
> For devices which VF support depends on loaded FW we
> have the pci_sriov_{g,s}et_totalvfs() API.  However, this API
> uses 0 as a special "unset" value, meaning drivers can't limit
> sriov_totalvfs to 0.  Change the special value to be U16_MAX.
> Use simple min() to determine actual totalvfs.

Please use a PCI_MAX_VFS or similar define instead of plain U16_MAX or ~0.