Re: [PATCH 4/5] efi x86: clear EFI_RUNTIME_SERVICES bit in case failures other than SetVirtualAddressMap

[Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>]

On Tue, 12 Aug, at 02:10:21PM, Dave Young wrote:
> If enter virtual mode failed due to some reason other than the efi call
> the EFI_RUNTIME_SERVICES bit in efi.flags should be cleared thus users
> of efi runtime services can check the bit and handle the case instead of
> assume efi runtime is ok.
> 
> Per Matt, if efi call SetVirtualAddressMap fails we will be not sure it's safe
> to make any assumptions about the state of the system. so kernel panics instead
> of clears EFI_RUNTIME_SERVICES bit.
> 
> Signed-off-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  arch/x86/platform/efi/efi.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)

[...]

> @@ -882,8 +886,10 @@ static void __init __efi_enter_virtual_mode(void)
>  
>  void __init efi_enter_virtual_mode(void)
>  {
> -	if (efi_enabled(EFI_PARAVIRT))
> +	if (efi_enabled(EFI_PARAVIRT)) {
> +		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
>  		return;
> +	}

The EFI_PARAVIRT folks purposely do not set this bit, so there should be
no reason to clear it here.

-- 
Matt Fleming, Intel Open Source Technology Center