Messages in this thread | | | Date | Fri, 21 Oct 2022 01:07:01 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH v4 3/4] fpga: dfl: add basic support DFHv1 |
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On Thu, Oct 20, 2022 at 02:26:09PM -0700, matthew.gerlach@linux.intel.com wrote: > From: Matthew Gerlach <matthew.gerlach@linux.intel.com> > > Add generic support for MSI-X interrupts for DFL devices. > > The location of a feature's registers is explicitly > described in DFHv1 and can be relative to the base of the DFHv1 > or an absolute address. Parse the location and pass the information > to DFL driver.
...
> +static void *find_param(void *base, resource_size_t max, int param)
Why base can't be u64 * to begin with?
> +{ > + int off = 0; > + u64 v, next; > + > + while (off < max) {
Maybe you need a comment somewhere to tell that the caller guarantees that max won't provoke OOB accesses.
> + v = *(u64 *)(base + off);
Okay, if offset is not multiple of at least 4, how do you guarantee no exception on the architectures with disallowed misaligned accesses?
Making base to be u64 * solves this, but you need to take care to provide offset in terms of u64 words.
> + if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v)) > + return base + off + DFHv1_PARAM_DATA; > + > + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v); > + off += next & ~DFHv1_PARAM_HDR_NEXT_MASK; > + if (next & DFHv1_PARAM_HDR_NEXT_EOL) > + break; > + > + } > + > + return NULL; > +}
...
> + /* > + * DFHv0 only provides mmio resource information for each feature
MMIO
> + * in the DFL header. There is no generic interrupt information. > + * Instead, features with interrupt functionality provide > + * the information in feature specific registers. > + */
...
> + if (!finfo->param_size) > break;
This is redundant as it's implied by find_param().
> + p = find_param(params, finfo->param_size, DFHv1_PARAM_ID_MSI_X); > + if (!p) > break;
...
> +static int dfh_get_psize(void __iomem *dfh_base, resource_size_t max) > +{ > + int size = 0; > + u64 v, next; > + > + if (!FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS, > + readq(dfh_base + DFHv1_CSR_SIZE_GRP))) > + return 0; > + > + while (size + DFHv1_PARAM_HDR < max) { > + v = readq(dfh_base + DFHv1_PARAM_HDR + size); > + > + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v); > + if (!(next & ~DFHv1_PARAM_HDR_NEXT_MASK)) > + return -EINVAL; > + > + size += next & ~DFHv1_PARAM_HDR_NEXT_MASK; > + > + if (next & DFHv1_PARAM_HDR_NEXT_EOL) > + return size;
These 3 looks like they deserve different fields and hence separate FIELD_GET() will return exactly what we need without additional masking, right?
> + } > + > + return -ENOENT; > +}
...
> + if (dfh_psize > 0) {
Isn't this implied by memcpy_fromio()? I mean if it's 0, nothing bad will happen if you call the above directly.
> + memcpy_fromio(finfo->params, > + binfo->ioaddr + ofst + DFHv1_PARAM_HDR, dfh_psize); > + finfo->param_size = dfh_psize; > + }
...
> finfo->mmio_res.flags = IORESOURCE_MEM; > + if (dfh_ver == 1) { > + v = readq(binfo->ioaddr + ofst + DFHv1_CSR_ADDR); > + if (v & DFHv1_CSR_ADDR_REL) > + finfo->mmio_res.start = v & ~DFHv1_CSR_ADDR_REL; > + else > + finfo->mmio_res.start = binfo->start + ofst + > + FIELD_GET(DFHv1_CSR_ADDR_MASK, v); > + > + v = readq(binfo->ioaddr + ofst + DFHv1_CSR_SIZE_GRP); > + finfo->mmio_res.end = finfo->mmio_res.start + > + FIELD_GET(DFHv1_CSR_SIZE_GRP_SIZE, v) - 1; > + } else { > + finfo->mmio_res.start = binfo->start + ofst; > + finfo->mmio_res.end = finfo->mmio_res.start + size - 1; > + }
You may define
resource_size_t start, end;
locally and simplify above quite a bit.
...
> +void *dfh_find_param(struct dfl_device *dfl_dev, int param);
+ Blank line.
> #endif /* __LINUX_DFL_H */
-- With Best Regards, Andy Shevchenko
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