Re: [Xen-devel] [PATCH v2 14/16] Xen: EFI: Parse DT parameters for Xen specific UEFI

[Shannon Zhao]

On 2016/1/19 21:43, Mark Rutland wrote:
> On Tue, Jan 19, 2016 at 09:19:05PM +0800, Shannon Zhao wrote:
> > On 2016/1/18 23:41, Stefano Stabellini wrote:
> > > CC'ing Matt Fleming
> > >
> > > On Fri, 15 Jan 2016, Shannon Zhao wrote:
> > > > From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > > > @@ -520,15 +531,28 @@ static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
> > > >   				       int depth, void *data)
> > > >   {
> > > >   	struct param_info *info = data;
> > > > +	struct params *dt_params;
> > > > +	unsigned int size;
> > > >   	const void *prop;
> > > >   	void *dest;
> > > >   	u64 val;
> > > >   	int i, len;
> > > >
> > > > -	if (depth != 1 || strcmp(uname, "chosen") != 0)
> > > > -		return 0;
> > > > +	if (efi_enabled(EFI_PARAVIRT)) {
> > > > +		if (depth != 2 || strcmp(uname, "uefi") != 0)
> > >
> > > You are already introducing this check in the previous patch when
> > > setting EFI_PARAVIRT, why do this again now?  But if we need to do this
> > > check again, then, like Mark suggested, it should be done against the
> > > full path.
> > This check just wants to confirm that the current node is the "uefi"
> > node and we can parse it with xen_fdt_params now.
>
> There is no single "uefi" node as many nodes can share that name. There
> is at most a single, /hypervisor/uefi node, as that is qualified by a
> full path.
Sure, I will check it by full path.

> Checking the leaf node name, as above, is insufficient. For example, the
> below will be accepted:
>
> * /chosen/uefi
> * /foo/uefi
> * /not-a-hypervisor/uefi
>
> Any of these could exist in addition to a /hypervisor/uefi node, and
> could appear ealier or later in the DTB.
>
> There may be reasons to add such nodes in future, and regardless we
> should not read properties from an invalid/wrong node.
>
> Thanks,
> Mark.

--
Shannon