Re: [PATCH v4] efi: Avoid calling boot services after ExitBootServices()

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-06-09 at 14:05 +0100, Ross Lagerwall wrote:
> On 06/09/2015 01:53 PM, Ian Campbell wrote:
> > On Tue, 2015-06-09 at 12:51 +0100, Jan Beulich wrote:
> >>>>> On 09.06.15 at 12:36, <ross.lagerwall@citrix.com> wrote:
> >>> ping
> >>
> >> I'm still waiting for the ARM maintainers to ack ...
> >>
> >>>> --- a/xen/arch/arm/efi/efi-boot.h
> >>>> +++ b/xen/arch/arm/efi/efi-boot.h
> >>>> @@ -522,6 +522,11 @@ static void __init efi_arch_blexit(void)
> >>>>            efi_bs->FreePool(memmap);
> >>>>    }
> >>>>
> >>>> +static void __init efi_arch_halt(void)
> >>>> +{
> >>>> +    stop_cpu();
> >>>> +}
> >>>> +
> >>>>    static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
> >>>>    {
> >>>>        if ( (unsigned long)loaded_image->ImageBase & ((1 << 12) - 1) )
> >>
> >> ... this.
> >
> > I think it is ok, it does a bit more than the x86 variant, which is that
> > it would interlock correctly with __cpu_die, where the open coded on x86
> > wouldn't (assuming you have any interlock anyway.
> >
> > In terms of the rest of the patch, are those two places changed to use
> > SystemTable->BootServices instead of efi_bs, if the point of the patch
> > is to not use BootServices after exit is called?
> >
> 
> GetMemoryMap() and ExitBootServices() are the only functions explicitly 
> allowed after the first call to ExitBootServices() so they are called 
> via SystemTable->BootServices. efi_bs is set to NULL to ensure that no 
> other bootservices are called.

I see. That might be worth a mention in the commit log?