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SubjectRE: [PATCH] fpga: dfl: pci: gracefully handle misconfigured port entries


On Wed, 21 Apr 2021, Wu, Hao wrote:

>> Subject: [PATCH] fpga: dfl: pci: gracefully handle misconfigured port entries
>>
>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>
>> Gracefully ignore misconfigured port entries encountered in
>> incorrect FPGA images.
>>
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.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,
>> 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;
>> + }
>
> Will it be a real problem that multiple ports are inside one BAR but different offsets?
>
> Hao

I don't think multiple ports within a single BAR is something that has
been supported in the past. The genesis for this patch was a
misconfigured port entry pointing to BAR0. BAR0 had already been mapped
for the FME and remapping BAR0 failed resulting in enumeration failure.

Matthew

>
>> +
>> 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);
>> + continue;
>> + }
>>
>> + len -= offset;
>> + bars |= BIT(bar);
>> dfl_fpga_enum_info_add_dfl(info, start, len);
>> }
>> } else if (dfl_feature_is_port(base)) {
>> --
>> 1.8.3.1
>
>

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