On Tue, 20 Oct 2020 at 08:20, ivanhu <ivan.hu@xxxxxxxxxxxxx> wrote: > > > On 10/19/20 7:25 PM, Heinrich Schuchardt wrote: > > On 19.10.20 13:01, Ard Biesheuvel wrote: > >> On Mon, 19 Oct 2020 at 13:00, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > >>> On 19.10.20 12:03, Ard Biesheuvel wrote: > >>>> On Mon, 19 Oct 2020 at 12:00, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > >>>>> On 19.10.20 11:31, Ard Biesheuvel wrote: > >>>>>> On Wed, 14 Oct 2020 at 20:41, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > >>>>>>> On 14.10.20 19:58, Ard Biesheuvel wrote: > >>>>>>>> On Wed, 14 Oct 2020 at 19:45, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > >>>>>>>>> On 14.10.20 19:31, Heinrich Schuchardt wrote: > >>>>>>>>>> Dear all, > >>>>>>>>>> > >>>>>>>>>> the fwts fails on U-Boot due to testing for a non-existent > >>>>>>>>>> RuntimeServicesSupported variable. > >>>>>>>>>> > >>>>>>>>>> If you look at the UEFI specification 2.8 (Errata B) [1] you will > >>>>>>>>>> discover in the change log: > >>>>>>>>>> > >>>>>>>>>> 2.8 A2049 > >>>>>>>>>> RuntimeServicesSupported EFI variable should be a config table > >>>>>>>>>> February 2020 > >>>>>>>>>> > >>>>>>>>>> Please, read the configuration table to determine if a runtime service > >>>>>>>>>> is available on UEFI 2.8 systems. > >>>>>>>>>> > >>>>>>>>>> On lower UEFI firmware version neither the variable nor the table exists. > >>>>>>>>>> > >>>>>>>>>> Best regards > >>>>>>>>>> > >>>>>>>>>> Heinrich > >>>>>>>>>> > >>>>>>>>>> [1] UEFI Specification Version 2.8 (Errata B) (released June 2020), > >>>>>>>>>> https://uefi.org/sites/default/files/resources/UEFI%20Spec%202.8B%20May%202020.pdf > >>>>>>>>>> > >>>>>>>>> Hello Ard, > >>>>>>>>> > >>>>>>>>> what is your idea how the EFI_RT_PROPERTIES_TABLE shall be exposed to > >>>>>>>>> the efi_test driver? > >>>>>>>>> > >>>>>>>>> Will the EFI runtime wrapper simply return EFI_UNSUPPORTED if the > >>>>>>>>> function is not marked as supported in the table? Or will the > >>>>>>>>> configuration table itself be make available? > >>>>>>>>> > >>>>>>>> The UEFI spec permits that runtime services return EFI_UNSUPPORTED at > >>>>>>>> runtime, but requires that they are marked as such in the > >>>>>>>> EFI_RT_PROPERTIES_TABLE. > >>>>>>>> > >>>>>>>> So assuming that the purpose of efi_test is compliance with the spec, > >>>>>>>> it should only allow EFI_UNSUPPORTED as a return value for each of the > >>>>>>>> tested runtime services if it is omitted from > >>>>>>>> efi.runtime_supported_mask. > >>>>>>>> > >>>>>>>> Since the efi_test ioctl returns both an error code and the actual EFI > >>>>>>>> status code, we should only fail the call on a EFI_UNSUPPORTED status > >>>>>>>> code if the RTPROP mask does not allow that. > >>>>>>>> > >>>>>>>> E.g., > >>>>>>>> > >>>>>>>> --- a/drivers/firmware/efi/test/efi_test.c > >>>>>>>> +++ b/drivers/firmware/efi/test/efi_test.c > >>>>>>>> @@ -265,7 +265,12 @@ static long efi_runtime_set_variable(unsigned long arg) > >>>>>>>> goto out; > >>>>>>>> } > >>>>>>>> > >>>>>>>> - rv = status == EFI_SUCCESS ? 0 : -EINVAL; > >>>>>>>> + if (status == EFI_SUCCESS || > >>>>>>>> + (status == EFI_UNSUPPORTED && > >>>>>>>> + !efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))) > >>>>>>>> + rv = 0; > >>>>>>>> + else > >>>>>>>> + rv = -EINVAL; > >>>>>>>> > >>>>>>>> out: > >>>>>>>> kfree(data); > >>>>>>>> > >>>>>>>> > >>>>>>>> Do you think that could work? > >>>>>>>> > >>>>>>> The current fwts implementation assumes that EFI_UNSUPPORTED leads to > >>>>>>> ioctl() returning -1. This value should not be changed. It would be > >>>>>>> preferable to use another error code than -EINVAL, e.g. -EDOM if there > >>>>>>> is a mismatch with the EFI_RT_PROPERTIES_TABLE configuration table. Then > >>>>>>> a future verision of fwts can evaluate errno to discover the problem. > >>>>>>> > >>>>>>> Do I read you correctly: the EFI runtime wrapper does not fend of calls > >>>>>>> to runtime services marked as disallowed in EFI_RT_PROPERTIES_TABLE? > >>>>>>> Directly returning an error code might help to avoid crashes on > >>>>>>> non-compliant firmware. > >>>>>>> > >>>>>> It is not the kernel's job to work around non-compliant firmware. The > >>>>>> EFI spec is crystal clear that every runtime service needs to be > >>>>>> implemented, but is permitted to return EFI_UNSUPPORTED after > >>>>>> ExitBootServices(). This means EFI_RT_PROPERTIES_TABLE does not tell > >>>>>> you calling certain runtime services is disallowed, it tells you that > >>>>>> there is no point in even trying. That is why users such as efi-pstore > >>>>>> now take this information into account in their probe path (and > >>>>>> efivarfs will only mount read/write if SetVariable() is not marked as > >>>>>> unsupported). > >>>>>> > >>>>> How about the return code? > >>>>> > >>>> As I attempted to explain, I think EFI_UNSUPPORTED should not be > >>>> reported as an error if RT_PROP_TABLE permits it. The caller has > >>>> access to the raw efi_status_t that was returned, so it can > >>>> distinguish between the two cases. > >>>> > >>> The fwts tires to figure out if a firmware implementation is compliant. > >>> > >>> The return value according to you suggestion would be as follows > >>> depending on the UEFI status and the entry in EFI_RT_PROPERTIES_TABLE. > >>> > >>> | EFI_SUCCESS | EFI_UNSUPPORTED | EFI_INVALID_PARAMETER > >>> ----------|--------------|-----------------|---------------------- > >>> Available | | | > >>> according | 0 | -EINVAL | -EINVAL > >>> EFT_RT_PRO| | | > >>> ------------------------------------------------------------------- > >>> Not | | | > >>> available | | | > >>> according | 0 | 0 | -EINVAL > >>> EFT_RT_PRO| | | > >>> ------------------------------------------------------------------- > >>> > >>> fwts would not be able to detect that according to the > >>> EFI_RT_PROPERTIES_TABLE the service is marked as not available > >>> but returns a value other than EFI_UNSUPPORTED. > >>> > >> But that would be permitted by the spec anyway. A runtime service is > >> not required to always return EFI_UNSUPPORTED if it is marked as > >> unavaialble in EFI_RT_PROP. > >> > > In the chapter "EFI_RT _PROPERTIES_TABLE" you can find this description: > > > > "*RuntimeServicesSupported* mask of which calls are or are not > > supported, where a bit set to 1 indicates that the call is supported, > > and 0 indicates that it is not." > > > > This leaves no room for implementing a service that is marked as not > > supported. > > > > In the descriptions of the return codes of the individual runtime services: > > > > "*EFI_UNSUPPORTED* This call is not supported by this platform at the > > time the call is made. The platform should describe this runtime service > > as unsupported at runtime via an EFI_RT_PROPERTIES_TABLE configuration > > table." > > From the spec, it clearly describes > > If a platform cannot support calls defined in EFI_RUNTIME_SERVICES after > ExitBootServices() is called, that platform is permitted to provide > implementations of those runtime services that return EFI_UNSUPPORTED > when invoked at runtime. On such systems, an EFI_RT_PROPERTIES_TABLE > configuration table should be published describing which runtime > services are supported at runtime. > > I think it's better not to modify efi_test base on the > EFI_RT_PROPERTIES_TABLE or RuntimeServicesSupported, let efi_test be > simply ioctl and FWTS tests can do the modifications. > Doesn't that mean FTWS would need to be able to access the EFI_RT_PROPERTIES_TABLE?
