linux-kernel - Re: [PATCH 4/4] arm64: kexec_image: Implement arch_kexec_locate_mem

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Date:   Fri, 28 May 2021 10:05:47 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Will Deacon <will@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Bhupesh SHARMA <bhupesh.sharma@...aro.org>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Dave Young <dyoung@...hat.com>,
        Moritz Fischer <mdf@...nel.org>, kernel-team@...roid.com
Subject: Re: [PATCH 4/4] arm64: kexec_image: Implement arch_kexec_locate_mem_hole()

On Thu, 27 May 2021 18:37:37 +0100,
Catalin Marinas <catalin.marinas@....com> wrote:
> 
> On Wed, May 26, 2021 at 08:05:31PM +0100, Marc Zyngier wrote:
> > Provide an arm64-specific implementation for arch_kexec_locate_mem_hole(),
> > using the resource tree instead of memblock, and respecting
> > the reservations added by EFI.
> > 
> > This ensures that kexec_file is finally reliable.
> > 
> > Reported-by: Moritz Fischer <mdf@...nel.org>
> > Signed-off-by: Marc Zyngier <maz@...nel.org>
> 
> It would have been clearer if __walk_iomem_res_desc() was able to do
> such child res excluding callback (if asked via a new flag/arg) directly
> but it's too late in the day to figure out if it's possible. It would
> save us from another callback in the arch code.

Yeah, that should be possible with some minor refactoring of the
generic and x86 code, allowing us to get rid of the double arch
callback circus.

It would also make the locking a bit saner, but also change it for all
the callers... I'll have a play with it.

> But if it's not possible or you want to stick to this approach, fine
> by me:
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@....com>

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.