Re: arm64: Kexec: Warning: virt_to_phys used for non-linear address

[Will Deacon <will@kernel.org>]

On Thu, Aug 22, 2024 at 02:28:03AM -0700, Breno Leitao wrote:
> On Mon, Jun 24, 2024 at 12:36:14PM +0100, Will Deacon wrote:
> > On Tue, Jun 18, 2024 at 12:36:03PM +0100, Mark Rutland wrote:
> > > On Tue, Jun 18, 2024 at 01:49:22AM -0700, Breno Leitao wrote:
> 
> > > > Since __pa() is a macro to __virt_to_phys():
> > > > 
> > > > 	#define __pa(x)                 __virt_to_phys((unsigned long)(x))
> > > > 
> > > > I am curious why this address is special that makes __virt_to_phys()
> > > > unhappy.
> > > 
> > > It's a fixmap address rather than a linear-map address. Confusingly
> > > 'virt' generally means the linear map rather than any virtual address,
> > > and usually virt_to_*() only work on linear map addresses.
> > > 
> > > I'm not sure how to fix this; the major reason we fixmap the FDT is so
> > > that it can be anywhere in memory (and e.g. may not be in the linear map
> > > at all), so we can't always generate a linear map VA.
> > > 
> > > We could stash the PA at boot time, and pass this as an argument to
> > > of_kexec_alloc_and_setup_fdt().
> > 
> > Yeah, if it was passed as an additional argument to early_init_dt_scan(),
> > then the core could could track it. Alternatively, we'd need a helper
> > macro to get the PA and have an arm64-variant for the fixmap (everybody
> > else could use __pa()).
> > 
> > > Rob, any thoughts? I couldn't see a neat way of doing this, but maybe we
> > > could initialise an initial_boot_params_phys at setup time, with a bit
> > > of churn to early_init_dt_verify() and friends?
> > 
> > Rob?
> 
> Hello, is there anything I can do or test to have this moving?

I've not seen anything from Rob, so the best bet is probably to see if
you can hack up a patch to fix it yourself and then cc the rest of us
when you post it.

Will