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. Cheers, Ivan > > Best regards > > Heinrich >
