linux-kernel - Re: [PATCH] PCI: Init NumVFs register to zero in sriov

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Message-ID: <CAE9FiQUV2cmFgfX78GYbcbuVvpefnteqv-1_eMujjOBZx7_f+A@mail.gmail.com>
Date:	Thu, 14 Nov 2013 22:59:58 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ethan Zhao <ethan.kernel@...il.com>
Cc:	Yu Zhao <yu.zhao@...el.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: Init NumVFs register to zero in sriov_init()

On Wed, Nov 13, 2013 at 5:57 PM, Ethan Zhao <ethan.kernel@...il.com> wrote:
> On Wed, Nov 6, 2013 at 10:49 PM, ethan.zhao <ethan.kernel@...il.com> wrote:
>> Though no specification about NumVFs register initial value after POST, to void the confusion
>> lspci output as following before VF was enabled, we should clear the NumVFs value left by BIOS
>> to zero:

Does BIOS need to clear it?


>>
>> $lspci -vvv -s 03:00.0
>> Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01)
>> ~
>> Capabilities: [160 v1] Single Root I/O Virtualization (SR-IOV)
>>                 IOVCap: Migration-, Interrupt Message Number: 000
>>                 IOVCtl: Enable+ Migration- Interrupt- MSE+ ARIHierarchy+
>>                 IOVSta: Migration-
>>                 Initial VFs: 64, Total VFs: 64, Number of VFs: 64, Function Dependency Link: 00
>>                                                               ^dazed !
>> ~

just display problem?

>> Signed-off-by: ethan.zhao <ethan.kernel@...il.com>
>> ---
>>  drivers/pci/iov.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>> index de8ffac..a4941ad 100644
>> --- a/drivers/pci/iov.c
>> +++ b/drivers/pci/iov.c
>> @@ -439,6 +439,8 @@ static int sriov_init(struct pci_dev *dev, int pos)
>>
>>  found:
>>         pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
>> +       /* VF Enable is cleared, so we could init the NumVFs register to 0 */
>> +       pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
>>         pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
>>         pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
>>         if (!offset || (total > 1 && !stride))

Thanks

Yinghai
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