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

[matthew . gerlach]

On Tue, 20 Apr 2021, Tom Rix wrote:


On 4/20/21 10:27 AM, matthew.gerl...@linux.intel.com wrote:
From: Matthew Gerlach <matthew.gerl...@linux.intel.com>

Gracefully ignore misconfigured port entries encountered in
incorrect FPGA images.

Signed-off-by: Matthew Gerlach <matthew.gerl...@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,
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)) {