From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <55F8BF72.5030404@oracle.com> Date: Wed, 16 Sep 2015 09:01:38 +0800 From: ethan zhao MIME-Version: 1.0 To: Bjorn Helgaas CC: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iov: initialize NumVFs register to 0 at the end of sriov_init() References: <1440150685-6690-1-git-send-email-ethan.zhao@oracle.com> <20150915161016.GB27964@google.com> In-Reply-To: <20150915161016.GB27964@google.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: On 2015/9/16 0:10, Bjorn Helgaas wrote: > On Fri, Aug 21, 2015 at 06:51:25PM +0900, Ethan Zhao wrote: >> After commit 4449f079722c ("PCI: Calculate maximum number of buses >> required for VFs"),the initial value of NumVFs register was set to >> non-zero after sriov_init() and no VFs was enabled in device driver. >> this changed the behaviour of kernel exported by lspci and sysfs etc. >> so this patch initialize the NumVFs register to zero after the >> calculation of max_VF_buses was done. >> >> Tested on stable 4.1 and passed building on stable 4.2-rc7 >> >> Signed-off-by: Ethan Zhao >> Tested-by: Sriharsha Yadagudde >> --- >> drivers/pci/iov.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >> index ee0ebff..6969084 100644 >> --- a/drivers/pci/iov.c >> +++ b/drivers/pci/iov.c >> @@ -476,6 +476,7 @@ found: >> dev->is_physfn = 1; >> iov->max_VF_buses = virtfn_max_buses(dev); >> >> + pci_iov_set_numvfs(dev, 0); > I think it would be better to put this in virtfn_max_buses(), where we > clobbered numVFs in the first place. I'd also read the original value and > restore it, e.g., > > pci_read_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, &numvfs); > for (nr_virtfn = 1; nr_virtfn <= iov->total_VFs; nr_virtfn++) { > ... > } > pci_iov_set_numvfs(dev, numvfs); > return max; > > I know sriov_init() sets numVFs to zero before it calls virtfn_max_buses(), > but why rely on that extra knowledge? Yes, I think also virtfn_max_buses() should restore the register before it returns. Will revise it and resend. Thanks, Ethan >> return 0; >> >> failed: >> -- >> 1.8.3.1 >>