Re: [RFC PATCH v2 3/4] cxl/mem: Add CDAT table reading from DOE

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> +static int cdat_to_buffer(struct pcie_doe *doe, u32 *buffer, size_t length)
> +{
> +	int entry_handle = 0;
> +	int rc;
> +
> +	do {
> +		u32 cdat_request_pl = CDAT_DOE_REQ(entry_handle);
> +		u32 cdat_response_pl[32];
> +		struct pcie_doe_exchange ex = {
> +			.vid = PCI_DVSEC_VENDOR_ID_CXL,
> +			.protocol = CXL_DOE_PROTOCOL_TABLE_ACCESS,
> +			.request_pl = &cdat_request_pl,
> +			.request_pl_sz = sizeof(cdat_request_pl),
> +			.response_pl = cdat_response_pl,
> +			.response_pl_sz = sizeof(cdat_response_pl),
> +		};
> +		size_t entry_dw;
> +		u32 *entry;
> +
> +		rc = pcie_doe_sync(doe, &ex);
> +		if (rc < 0)
> +			return rc;
> +
> +		entry = cdat_response_pl + 1;
> +		entry_dw = rc / sizeof(u32);

Could you >> 2?
> +		/* Skip Header */
> +		entry_dw -= 1;
> +		entry_dw = min(length / 4, entry_dw);

Ditto here on length?

Also should you double check that length is not greater than
sizeof(cdat_respone_pl)?

> +		memcpy(buffer, entry, entry_dw * sizeof(u32));
> +		length -= entry_dw * sizeof(u32);

Would it be just easier to convert length at the start to be >> 2
instead of this * and / ?


> +		buffer += entry_dw;
> +		entry_handle = FIELD_GET(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, cdat_response_pl[0]);
> +
> +	} while (entry_handle != 0xFFFF);
> +
> +	return 0;
> +}
> +