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

From: Moritz Fischer
Date: Sun Apr 25 2021 - 21:22:03 EST


On Tue, Apr 20, 2021 at 12:19:42PM -0700, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
>
>
> On Tue, 20 Apr 2021, Tom Rix wrote:
>
> >
> > On 4/20/21 10:27 AM, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> > > From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> > >
> > > Gracefully ignore misconfigured port entries encountered in
> > > incorrect FPGA images.
> > >
> > > Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> > > ---
> > > 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);
Do you want pa or px here?

> >
> > 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)) {
> >
> >

- Moritz