linux-kernel - Re: [PATCH] fpga: dfl: pci: gracefully handle misconfigured port entries

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Date:   Tue, 20 Apr 2021 12:19:42 -0700 (PDT)
From:   matthew.gerlach@...ux.intel.com
To:     Tom Rix <trix@...hat.com>
cc:     hao.wu@...el.com, linux-fpga@...r.kernel.org,
        linux-kernel@...r.kernel.org, yilun.xu@...el.com,
        russell.h.weight@...el.com, mdf@...nel.org
Subject: Re: [PATCH] fpga: dfl: pci: gracefully handle misconfigured port
 entries



On Tue, 20 Apr 2021, Tom Rix wrote:

>
> On 4/20/21 10:27 AM, matthew.gerlach@...ux.intel.com wrote:
>> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>> 
>> Gracefully ignore misconfigured port entries encountered in
>> incorrect FPGA images.
>> 
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>> ---
>>   drivers/fpga/dfl-pci.c | 16 +++++++++++++++-
>>   1 file changed, 15 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
>> index b44523e..660d3b6 100644
>> --- a/drivers/fpga/dfl-pci.c
>> +++ b/drivers/fpga/dfl-pci.c
>> @@ -212,6 +212,7 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
> Does something similar need to be added to find_dfls_by_vsec ?
>>   	int port_num, bar, i, ret = 0;
>>   	resource_size_t start, len;
>>   	void __iomem *base;
>> +	int bars = 0;
>>   	u32 offset;
>>   	u64 v;
>>   @@ -228,6 +229,7 @@ static int find_dfls_by_default(struct pci_dev 
>> *pcidev,
>>   	if (dfl_feature_is_fme(base)) {
>>   		start = pci_resource_start(pcidev, 0);
>>   		len = pci_resource_len(pcidev, 0);
>> +		bars |= BIT(0);
>>     		dfl_fpga_enum_info_add_dfl(info, start, len);
>>   @@ -253,9 +255,21 @@ static int find_dfls_by_default(struct pci_dev 
>> *pcidev,
>>   			 */
>>   			bar = FIELD_GET(FME_PORT_OFST_BAR_ID, v);
>>   			offset = FIELD_GET(FME_PORT_OFST_DFH_OFST, v);
>> +			if (bars & BIT(bar)) {
>> +				dev_warn(&pcidev->dev, "skipping bad port BAR 
>> %d\n", bar);
>> +				continue;
>> +			}
>> +
>>   			start = pci_resource_start(pcidev, bar) + offset;
>> -			len = pci_resource_len(pcidev, bar) - offset;
>> +			len = pci_resource_len(pcidev, bar);
>> +			if (offset >= len) {
>> +				dev_warn(&pcidev->dev, "bad port offset %u >= 
>> %pa\n",
>> +					 offset, &len);
>
> why %pa,&len for instead of %u,len ?
>
> Tom

Hi Tom,

The variable len is of type resource_size_t, and I am following what it 
says to do in Documentation/core-api/printk-formats.rst:

Physical address types phys_addr_t
----------------------------------

::

         %pa[p]  0x01234567 or 0x0123456789abcdef

For printing a phys_addr_t type (and its derivatives, such as
resource_size_t) which can vary based on build options, regardless of the
width of the CPU data path.

Passed by reference.

Matthew
>
>> +				continue;
>> +			}
>>   +			len -= offset;
>> +			bars |= BIT(bar);
>>   			dfl_fpga_enum_info_add_dfl(info, start, len);
>>   		}
>>   	} else if (dfl_feature_is_port(base)) {
>
>