Re: [PATCH v2 2/2] PCI: vmd: Issue vmd domain window reset

["Patel, Nirmal" <nirmal.patel@linux.intel.com>]

On 7/20/2021 3:42 PM, Bjorn Helgaas wrote:
> On Tue, Jul 20, 2021 at 01:50:09PM -0700, Nirmal Patel wrote:
>> In order to properly re-initialize the VMD domain during repetitive driver
>> attachment or reboot tests, ensure that the VMD root ports are re-initialized
>> to a blank state that can be re-enumerated appropriately by the PCI core.
>> This is performed by re-initializing all of the bridge windows to ensure
>> that PCI core enumeration does not detect potentially invalid bridge windows
>> and misinterpret them as firmware-assigned windows, when they simply may be
>> invalid bridge window information from a previous boot.
> Rewrap commit log to fit in 75 columns.  No problem about v2 vs v1.
I will take care of it.
>
>> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
>> Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>
>> ---
>>  drivers/pci/controller/vmd.c | 35 +++++++++++++++++++++++++++++++++++
>>  1 file changed, 35 insertions(+)
>>
>> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
>> index 6e1c60048774..e52bdb95218e 100644
>> --- a/drivers/pci/controller/vmd.c
>> +++ b/drivers/pci/controller/vmd.c
>> @@ -651,6 +651,39 @@ static int vmd_alloc_irqs(struct vmd_dev *vmd)
>>  	return 0;
>>  }
>>  
>> +
> Remove spurious blank line here.
Sure.
>
>> +static void vmd_domain_reset_windows(struct vmd_dev *vmd)
>> +{
>> +	u8 hdr_type;
>> +	char __iomem *addr;
>> +	int dev_seq;
>> +	u8 functions;
>> +	u8 fn_seq;
>> +	int max_devs = resource_size(&vmd->resources[0]) * 32;
>> +
>> +	for (dev_seq = 0; dev_seq < max_devs; dev_seq++) {
>> +		addr = VMD_DEVICE_BASE(vmd, dev_seq) + PCI_VENDOR_ID;
>> +		if (readw(addr) != PCI_VENDOR_ID_INTEL)
>> +			continue;
>> +
>> +		addr = VMD_DEVICE_BASE(vmd, dev_seq) + PCI_HEADER_TYPE;
>> +		hdr_type = readb(addr) & PCI_HEADER_TYPE_MASK;
>> +		if (hdr_type != PCI_HEADER_TYPE_BRIDGE)
>> +			continue;
>> +
>> +		functions = !!(hdr_type & 0x80) ? 8 : 1;
>> +		for (fn_seq = 0; fn_seq < functions; fn_seq++)
>> +		{
> Put "{" on previous line.
>
> Looks quite parallel to vmd_domain_sbr(), except that here we iterate
> through functions as well.  Why does vmd_domain_sbr() not need to
> iterate through functions?
I am not sure if there is VMD hardware with non zero functions.
>
>> +			addr = VMD_FUNCTION_BASE(vmd, dev_seq, fn_seq) + PCI_VENDOR_ID;
>> +			if (readw(addr) != PCI_VENDOR_ID_INTEL)
>> +				continue;
>> +
>> +			memset_io((VMD_FUNCTION_BASE(vmd, dev_seq, fn_seq) + PCI_IO_BASE),
>> +			 0, PCI_ROM_ADDRESS1 - PCI_IO_BASE);
> Make the lines above fit in 80 columns.
Sure.
>
>> +		}
>> +	}
>> +}
>> +
>>  static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>  {
>>  	struct pci_sysdata *sd = &vmd->sysdata;
>> @@ -741,6 +774,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>  		.parent = res,
>>  	};
>>  
>> +	vmd_domain_reset_windows(vmd);
>> +
>>  	sd->vmd_dev = vmd->dev;
>>  	sd->domain = vmd_find_free_domain();
>>  	if (sd->domain < 0)
>> -- 
>> 2.27.0
>>