Re: [PATCH v4 3/4] fpga: dfl: add basic support DFHv1

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Xu Yilun <yilun.xu@intel.com>
Cc: matthew.gerlach@linux.intel.com, hao.wu@intel.com,
	russell.h.weight@intel.com, basheer.ahmed.muddebihal@intel.com,
	trix@redhat.com, mdf@kernel.org, linux-fpga@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	tianfei.zhang@intel.com, corbet@lwn.net, jirislaby@kernel.org,
	geert+renesas@glider.be, niklas.soderlund+renesas@ragnatech.se,
	macro@orcam.me.uk, johan@kernel.org, lukas@wunner.de,
	ilpo.jarvinen@linux.intel.com, marpagan@redhat.com
Subject: Re: [PATCH v4 3/4] fpga: dfl: add basic support DFHv1
Date: Mon, 31 Oct 2022 00:06:28 +0200	[thread overview]
Message-ID: <Y171ZEHpOydtR4dW@smile.fi.intel.com> (raw)
In-Reply-To: <Y10l3NkIn0gsdVZq@yilunxu-OptiPlex-7050>

On Sat, Oct 29, 2022 at 09:08:44PM +0800, Xu Yilun wrote:
> On 2022-10-20 at 14:26:09 -0700, matthew.gerlach@linux.intel.com wrote:

> >  struct dfl_feature_info {
> >  	u16 fid;
> >  	u8 revision;
> > +	u8 dfh_version;
> >  	struct resource mmio_res;
> >  	void __iomem *ioaddr;
> >  	struct list_head node;
> >  	unsigned int irq_base;
> >  	unsigned int nr_irqs;
> > +	unsigned int param_size;
> > +	u64 params[];
> >  };

...

> > +	finfo = kzalloc(sizeof(*finfo) + dfh_psize, GFP_KERNEL);

This probably may use something from overflow.h.

> The u64 flexible array in the structure, but seems dfh_get_psize could
> not garantee 64bit aligned size.
> 
> What's the mandatory alignment of param data? If 64bit aligned, bit 33-34
> of PARAM_HDR should be reserved. If 32bit aligned, finfo:params should be
> u32[].

Isn't it guaranteed by the C standard / architecture ABI?

-- 
With Best Regards,
Andy Shevchenko