Re: [PATCH 1/3] riscv: Don't use va_pa_offset on kdump

[Palmer Dabbelt]

On Fri, 07 Jan 2022 10:03:59 PST (-0800), mick@xxxxxxxxxxxx wrote:
> Hello Palmer,
>
> Any updates on those 3 patches ?

Sorry, I hadn't realized these were fixes so they got stuck in the 
queue0.  I do now remember you saying you had some fixes at the RISC-V 
conference, but I guess that got lost as well.  Including something like 
"fix" or "-fixes" in a subject line always helps, but if I miss stuff 
IRC's always a good bet as that'll at least make sure I see it when I'm 
in front of the computer -- there's a lot of people who want things at 
these conferences.

It's too late for fixes, but it looks like things have been broken for a 
while so these will have to all get backported to stable regardless.

This is on for-next.

Thanks!

> Regards,
> Nick
>
> Στις 2021-11-26 20:04, Nick Kossifidis έγραψε:
> > On kdump instead of using an intermediate step to relocate the kernel,
> > that lives in a "control buffer" outside the current kernel's mapping,
> > we jump to the crash kernel directly by calling
> > riscv_kexec_norelocate().
> > The current implementation uses va_pa_offset while switching to
> > physical
> > addressing, however since we moved the kernel outside the linear
> > mapping
> > this won't work anymore since riscv_kexec_norelocate() is part of the
> > kernel mapping and we should use kernel_map.va_kernel_pa_offset, and
> > also
> > take XIP kernel into account.
> >
> > We don't really need to use va_pa_offset on riscv_kexec_norelocate, we
> > can just set STVEC to the physical address of the new kernel instead
> > and
> > let the hart jump to the new kernel on the next instruction after
> > setting
> > SATP to zero. This fixes kdump and is also simpler/cleaner.
> >
> > I tested this on the latest qemu and HiFive Unmatched and works as
> > expected.
> >
> > v2: I removed the direct jump after setting satp as suggested.
> >
> > Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear
> > mapping")
> >
> > Signed-off-by: Nick Kossifidis <mick@xxxxxxxxxxxx>
> > Reviewed-by: Alexandre Ghiti <alex@xxxxxxxx>
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.13
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.14