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

[Ross Lagerwall <ross.lagerwall@citrix.com>]

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.

Cheers,
-- 
Ross Lagerwall