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

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

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@xxxxxxxxxx> 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.
Cheers,
--
Ross Lagerwall

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