linux-kernel - Re: [PATCH v7 3/4] fpga: dfl: add basic support for DFHv1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.22.394.2212211421210.570436@rhweight-WRK1>
Date:   Wed, 21 Dec 2022 14:29:11 -0800 (PST)
From:   matthew.gerlach@...ux.intel.com
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
cc:     hao.wu@...el.com, yilun.xu@...el.com,
        Russ Weight <russell.h.weight@...el.com>,
        basheer.ahmed.muddebihal@...el.com, trix@...hat.com,
        mdf@...nel.org, linux-fpga@...r.kernel.org,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        tianfei.zhang@...el.com, corbet@....net,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        Jiri Slaby <jirislaby@...nel.org>, geert+renesas@...der.be,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        niklas.soderlund+renesas@...natech.se, macro@...am.me.uk,
        johan@...nel.org, Lukas Wunner <lukas@...ner.de>,
        marpagan@...hat.com, bagasdotme@...il.com
Subject: Re: [PATCH v7 3/4] fpga: dfl: add basic support for DFHv1



On Wed, 21 Dec 2022, Ilpo Järvinen wrote:

> On Tue, 20 Dec 2022, matthew.gerlach@...ux.intel.com wrote:
>
>> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>>
>> Version 1 of the Device Feature Header (DFH) definition adds
>> functionality to the DFL bus.
>>
>> A DFHv1 header may have one or more parameter blocks that
>> further describes the HW to SW.  Add support to the DFL bus
>> to parse the MSI-X parameter.
>>
>> The location of a feature's register set 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.
>>
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
>> ---
>> v7: no change
>>
>> v6: move MSI_X parameter definitions to drivers/fpga/dfl.h
>>
>> v5: update field names
>>     fix find_param/dfh_get_psize
>>     clean up mmio_res assignments
>>     use u64* instead of void*
>>     use FIELD_GET instead of masking
>>
>> v4: s/MSIX/MSI_X
>>     move kernel doc to implementation
>>     use structure assignment
>>     fix decode of absolute address
>>     clean up comment in parse_feature_irqs
>>     remove use of csr_res
>>
>> v3: remove unneeded blank line
>>     use clearer variable name
>>     pass finfo into parse_feature_irqs()
>>     refactor code for better indentation
>>     use switch statement for irq parsing
>>     squash in code parsing register location
>>
>> v2: fix kernel doc
>>     clarify use of DFH_VERSION field
>> ---
>
>> +static u64 *find_param(u64 *params, resource_size_t max, int param_id)
>> +{
>> +	u64 *end = params + max / sizeof(u64);
>> +	u64 v, next;
>> +
>> +	while (params < end) {
>> +		v = *params;
>> +		if (param_id == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
>> +			return params;
>> +
>> +		next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
>> +		params += next;
>> +		if (FIELD_GET(DFHv1_PARAM_HDR_NEXT_EOP, v))
>> +			break;
>> +	}
>> +
>> +	return NULL;
>> +}
>> +
>> +/**
>> + * dfh_find_param() - find data for the given parameter id
>> + * @dfl_dev: dfl device
>> + * @param: id of dfl parameter
>> + *
>> + * Return: pointer to parameter header on success, NULL otherwise.
>> + */
>> +u64 *dfh_find_param(struct dfl_device *dfl_dev, int param_id)
>> +{
>> +	return find_param(dfl_dev->params, dfl_dev->param_size, param_id);
>> +}
>> +EXPORT_SYMBOL_GPL(dfh_find_param);
>
> BTW, should there be a way for the caller to ensure the parameter is long
> enough?

The caller can look at the DFHv1_PARAM_HDR_NEXT_OFFSET field of the 
parameter header to see the size of the parameter block (header plus 
data).

>
> All callers probably want to ensure the length of the parameter is valid
> so it would perhaps make sense to add a parameter for the required
> (minimum) length?

Yes, all callers should ensure that the length of the parameter is valid. 
I will add another API call that performs length checking.

Thanks for the feedback,
Matthew Gerlach

>
>
> -- 
> i.
>