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

[Breno Leitao <leitao@debian.org>]

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?

Thanks