linux-kernel - Re: [PATCH] x86/efi: skip bgrt init for kexec reboot

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Date:	Wed, 3 Feb 2016 22:53:33 +0000
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Dave Young <dyoung@...hat.com>
Cc:	linux-efi@...r.kernel.org, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/efi: skip bgrt init for kexec reboot

On Thu, 04 Feb, at 05:42:00AM, Dave Young wrote:
> 
> On 01/27/16 at 07:20pm, Dave Young wrote:
> > For kexec reboot the bgrt image address could contains random data because
> > we have freed boot service areas in 1st kernel boot phase. One possible
> > result is kmalloc fail in efi_bgrt_init due to large random image size.
> > 
> > So change efi_late_init to avoid efi_bgrt_init in case kexec boot.
> > 
> > Signed-off-by: Dave Young <dyoung@...hat.com>
> > ---
> >  arch/x86/platform/efi/efi.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > --- linux-x86.orig/arch/x86/platform/efi/efi.c
> > +++ linux-x86/arch/x86/platform/efi/efi.c
> > @@ -531,7 +531,8 @@ void __init efi_init(void)
> >  
> >  void __init efi_late_init(void)
> >  {
> > -	efi_bgrt_init();
> > +	if (!efi_setup)
> > +		efi_bgrt_init();
> >  }
> >  
> >  void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
> 
> Matt, opinions about this patch?

Yeah, I'm not happy seeing efi_setup escaping into even more places,
nor am I happy to see more code paths introduced where kexec boot is
special-cased.

I'll reply with more details tomorrow.