Re: [PATCH] PCI: Add pci reset quirk for Huawei Intelligent NIC virtual function

[Chiqijun <chiqijun@huawei.com>]

On 2020/12/3 1:46, Alex Williamson wrote:
> On Wed, 2 Dec 2020 17:18:12 +0800
> Chiqijun <chiqijun@huawei.com> wrote:
> 
>> On 2020/11/30 23:46, Alex Williamson wrote:
>>> On Sat, 28 Nov 2020 17:29:19 -0600
>>> Bjorn Helgaas <helgaas@kernel.org> wrote:
>>>    
>>>> [+cc Alex]
>>>>
>>>> On Sat, Nov 28, 2020 at 02:18:25PM +0800, Chiqijun wrote:
>>>>> When multiple VFs do FLR at the same time, the firmware is
>>>>> processed serially, resulting in some VF FLRs being delayed more
>>>>> than 100ms, when the virtual machine restarts and the device
>>>>> driver is loaded, the firmware is doing the corresponding VF
>>>>> FLR, causing the driver to fail to load.
>>>>>
>>>>> To solve this problem, add host and firmware status synchronization
>>>>> during FLR.
>>>>
>>>> Is this because the Huawei Intelligent NIC isn't following the spec,
>>>> or is it because Linux isn't correctly waiting for the FLR to
>>>> complete?
>>>
>>> Seems like a spec compliance issue, I don't recall anything in the spec
>>> about coordinating FLR between VFs.
>>
>> The spec stipulates that the FLR time of a single VF does not exceed
>> 100ms, but when multiple VMs are reset concurrently in Linux, there will
>> be multiple VF parallel FLRs, VF of Huawei Intelligent NIC
>>    FLR will exceed 100ms in this case.
>>
>>>      
>>>> If this is a Huawei Intelligent NIC defect, is there documentation
>>>> somewhere (errata) that you can reference?  Will it be fixed in future
>>>> designs, so we don't have to add future Device IDs to the quirk?
>>>>   
>>>>> Signed-off-by: Chiqijun <chiqijun@huawei.com>
>>>>> ---
>>>>>    drivers/pci/quirks.c | 67 ++++++++++++++++++++++++++++++++++++++++++++
>>>>>    1 file changed, 67 insertions(+)
>>>>>
>>>>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>>>>> index f70692ac79c5..bd6236ea9064 100644
>>>>> --- a/drivers/pci/quirks.c
>>>>> +++ b/drivers/pci/quirks.c
>>>>> @@ -3912,6 +3912,71 @@ static int delay_250ms_after_flr(struct pci_dev *dev, int probe)
>>>>>    	return 0;
>>>>>    }
>>>>>    
>>>>> +#define PCI_DEVICE_ID_HINIC_VF  0x375E
>>>>> +#define HINIC_VF_FLR_TYPE       0x1000
>>>>> +#define HINIC_VF_OP             0xE80
>>>>> +#define HINIC_OPERATION_TIMEOUT 15000
>>>>> +
>>>>> +/* Device-specific reset method for Huawei Intelligent NIC virtual functions */
>>>>> +static int reset_hinic_vf_dev(struct pci_dev *pdev, int probe)
>>>>> +{
>>>>> +	unsigned long timeout;
>>>>> +	void __iomem *bar;
>>>>> +	u16 old_command;
>>>>> +	u32 val;
>>>>> +
>>>>> +	if (probe)
>>>>> +		return 0;
>>>>> +
>>>>> +	bar = pci_iomap(pdev, 0, 0);
>>>>> +	if (!bar)
>>>>> +		return -ENOTTY;
>>>>> +
>>>>> +	pci_read_config_word(pdev, PCI_COMMAND, &old_command);
>>>>> +
>>>>> +	/*
>>>>> +	 * FLR cap bit bit30, FLR ACK bit: bit18, to avoid big-endian conversion
>>>>> +	 * the big-endian bit6, bit10 is directly operated here
>>>>> +	 */
>>>>> +	val = readl(bar + HINIC_VF_FLR_TYPE);
>>>>> +	if (!(val & (1UL << 6))) {
>>>>> +		pci_iounmap(pdev, bar);
>>>>> +		return -ENOTTY;
>>>>> +	}
>>>
>>>
>>> I don't know exactly what this is testing, but it seems like a
>>> feature/capability test that can fail, why is it not done as part of
>>> the probe?  Can we define bit 6 with a macro?  Same for bit 10 in the
>>> VF op register below.
>>
>> The firmware of Huawei Intelligent NIC does not support this feature in
>> the old version. here is the reading ability to determine whether the
>> firmware supports it.
>> In the next patch, I will add a comment here and replace bit 6 and bit
>> 10 with macro definitions.
> 
> 
> The question remains why this is not done as part of the probe.  If the
> device firmware doesn't support it, isn't it better to try a regular
> FLR and have it return error if the time is exceeded rather than claim
> we have a functional device specific reset quirk that will always fail
> without ever attempting to FLR the VF?  Thanks,
> 
> Alex
> 

The firmware has always supported regular FLR. The regular FLR process 
waits for 100ms after the FLR is triggered and the FLR is considered to 
be completed, but the Huawei Intelligent NIC will exceed 100ms when the 
VF FLR is parallel, so we now need to increase the host to confirm that 
the firmware completes the FLR processing operation.
So in the probe stage, we return to support FLR, but there is no place 
to return whether the firmware supports FLR completion ack capability. 
We need to add checks during FLR, If the firmware does not support FLR 
completion ack capability, then return -ENOTTY, the kernel will still 
execute the regular FLR process.

>   
>>>>> +
>>>>> +	val = readl(bar + HINIC_VF_OP);
>>>>> +	val = val | (1UL << 10);
>>>>> +	writel(val, bar + HINIC_VF_OP);
>>>>> +
>>>>> +	/* Perform the actual device function reset */
>>>>> +	pcie_flr(pdev);
>>>>> +
>>>>> +	pci_write_config_word(pdev, PCI_COMMAND,
>>>>> +			      old_command | PCI_COMMAND_MEMORY);
>>>>> +
>>>>> +	/* Waiting for device reset complete */
>>>>> +	timeout = jiffies + msecs_to_jiffies(HINIC_OPERATION_TIMEOUT);
>>>
>>> Yikes, 15s timeout!
>>
>> Huawei Intelligent NIC supports a maximum of 496 VFs, so the total
>> timeout period is set to 15s, which will not reach the timeout time
>> under normal circumstances.
>>
>>>    
>>>>> +	do {
>>>>> +		val = readl(bar + HINIC_VF_OP);
>>>>> +		if (!(val & (1UL << 10)))
>>>>> +			goto reset_complete;
>>>>> +		msleep(20);
>>>>> +	} while (time_before(jiffies, timeout));
>>>>> +
>>>>> +	val = readl(bar + HINIC_VF_OP);
>>>>> +	if (!(val & (1UL << 10)))
>>>>> +		goto reset_complete;
>>>>> +
>>>>> +	pci_warn(pdev, "Reset dev timeout, flr ack reg: %x\n",
>>>>> +		 be32_to_cpu(val));
>>>>> +
>>>>> +reset_complete:
>>>>> +	pci_write_config_word(pdev, PCI_COMMAND, old_command);
>>>>> +	pci_iounmap(pdev, bar);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>    static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
>>>>>    	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82599_SFP_VF,
>>>>>    		 reset_intel_82599_sfp_virtfn },
>>>>> @@ -3923,6 +3988,8 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
>>>>>    	{ PCI_VENDOR_ID_INTEL, 0x0953, delay_250ms_after_flr },
>>>>>    	{ PCI_VENDOR_ID_CHELSIO, PCI_ANY_ID,
>>>>>    		reset_chelsio_generic_dev },
>>>>> +	{ PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HINIC_VF,
>>>>> +		reset_hinic_vf_dev },
>>>>>    	{ 0 }
>>>>>    };
>>>>>    
>>>>> -- 
>>>>> 2.17.1
>>>>>       
>>>>   
>>>
>>> .
>>>    
>>
> 
> .
>