linux-kernel - Re: [PATCH 1/1] efi/efi_test: read RuntimeServicesSupported

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Message-ID: <9feb54b4-447a-12f9-d781-e510623c2aef@gmx.de>
Date:   Wed, 2 Dec 2020 12:38:51 +0100
From:   Heinrich Schuchardt <xypron.glpk@....de>
To:     ivanhu <ivan.hu@...onical.com>, Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Colin King <colin.king@...onical.com>,
        fwts-devel@...ts.ubuntu.com
Subject: Re: [PATCH 1/1] efi/efi_test: read RuntimeServicesSupported

On 11/30/20 11:38 AM, ivanhu wrote:
>
>
> On 11/30/20 5:17 PM, Heinrich Schuchardt wrote:
>> On 11/30/20 9:16 AM, ivanhu wrote:
>>> Hi Heinrich,
>>>
>>> Thanks for the patch.
>>> It looks good to me, but I noticed that the runtime_supported_mask was
>>> introduced after 5.7-rc1.
>>> Maybe we should add the kernel version checking for the old kernels.
>>
>> This is a kernel patch. Why should we check the kernel version in the
>> kernel code?
>>
>> As patches may be back-ported we should not make any assumptions in fwts
>> based on the kernel version. If the ioctl() call fails with errno =
>> ENOTTY, we know that the kernel does not implement the ioctl call and we
>> have to assume that all runtime services are available.
>
> Sounds good to me,
> Acked-by: Ivan Hu <ivan.hu@...onical.com>
>
> And I will replace the reading RuntimeServicesSupported efi variable by
> using efi_test in fwts RuntimeServicesSupported tests.
>
> FWTS will still test those Unsupported Runtime services to check if it
> returns EFI_UNSUPPORTED correctly.
> Is that could solve your problem?
> If I remember correctly, the problem from you is not to test those
> marked Unsupported Runtime services. But from the Spec. 8.1 Runtime
> Services Rules and Restrictions,

The problem I reported was that it is impossible to test UEFI runtime
services on U-Boot because FWTS tries to read the non-existent
RuntimeServicesSupported UEFI variable and mistakenly assumes that if
the variable does not exist none of the runtime services is implemented.

The correct thing to do in FWTS is:

* read RuntimeServicesSupported via the ioctl
* if the ioctl fails assume that all runtime services
   are implemented
* if the ioctl fails with errno != ENOTTY write an error message
* for each runtime service marked as not supported
   check that it returns EFI_UNSUPPORTED
* for each service marked as supported
   check that it works correctly

Best regards

Heinrich

> "
> Note that this is merely a hint to the OS, which it is free to ignore,
> and so the platform is still required to provide callable
> implementations of unsupported runtime services that simply return
> EFI_UNSUPPORTED.
> "
>
> Cheers,
> Ivan
>>
>> Best regards
>>
>> Heinrich
>>
>>>
>>> Cheers,
>>> Ivan
>>>
>>> On 11/28/20 3:20 AM, Heinrich Schuchardt wrote:
>>>> Since the UEFI 2.8A specification the UEFI enabled firmware provides a
>>>> configuration table EFI_RT_PROPERTIES_TABLE which indicates which
>>>> runtime
>>>> services are enabled. The EFI stub reads this table and saves the
>>>> value of
>>>> the field RuntimeServicesSupported internally.
>>>>
>>>> The Firmware Test Suite requires the value to determine if UEFI runtime
>>>> services are correctly implemented.
>>>>
>>>> With this patch an IOCTL call is provided to read the value of the field
>>>> RuntimeServicesSupported, e.g.
>>>>
>>>>       #define EFI_RUNTIME_GET_SUPPORTED_MASK \
>>>>               _IOR('p', 0x0C, unsigned int)
>>>>       unsigned int mask;
>>>>       fd = open("/dev/efi_test", O_RDWR);
>>>>       ret = ioctl(fd, EFI_RUNTIME_GET_SUPPORTED_MASK, &mask);
>>>>
>>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
>>>> ---
>>>>    drivers/firmware/efi/test/efi_test.c | 16 ++++++++++++++++
>>>>    drivers/firmware/efi/test/efi_test.h |  3 +++
>>>>    2 files changed, 19 insertions(+)
>>>>
>>>> diff --git a/drivers/firmware/efi/test/efi_test.c
>>>> b/drivers/firmware/efi/test/efi_test.c
>>>> index ddf9eae396fe..47d67bb0a516 100644
>>>> --- a/drivers/firmware/efi/test/efi_test.c
>>>> +++ b/drivers/firmware/efi/test/efi_test.c
>>>> @@ -663,6 +663,19 @@ static long
>>>> efi_runtime_query_capsulecaps(unsigned long arg)
>>>>        return rv;
>>>>    }
>>>>
>>>> +static long efi_runtime_get_supported_mask(unsigned long arg)
>>>> +{
>>>> +    unsigned int __user *supported_mask;
>>>> +    int rv = 0;
>>>> +
>>>> +    supported_mask = (unsigned int *)arg;
>>>> +
>>>> +    if (put_user(efi.runtime_supported_mask, supported_mask))
>>>> +        rv = -EFAULT;
>>>> +
>>>> +    return rv;
>>>> +}
>>>> +
>>>>    static long efi_test_ioctl(struct file *file, unsigned int cmd,
>>>>                                unsigned long arg)
>>>>    {
>>>> @@ -699,6 +712,9 @@ static long efi_test_ioctl(struct file *file,
>>>> unsigned int cmd,
>>>>
>>>>        case EFI_RUNTIME_RESET_SYSTEM:
>>>>            return efi_runtime_reset_system(arg);
>>>> +
>>>> +    case EFI_RUNTIME_GET_SUPPORTED_MASK:
>>>> +        return efi_runtime_get_supported_mask(arg);
>>>>        }
>>>>
>>>>        return -ENOTTY;
>>>> diff --git a/drivers/firmware/efi/test/efi_test.h
>>>> b/drivers/firmware/efi/test/efi_test.h
>>>> index f2446aa1c2e3..117349e57993 100644
>>>> --- a/drivers/firmware/efi/test/efi_test.h
>>>> +++ b/drivers/firmware/efi/test/efi_test.h
>>>> @@ -118,4 +118,7 @@ struct efi_resetsystem {
>>>>    #define EFI_RUNTIME_RESET_SYSTEM \
>>>>        _IOW('p', 0x0B, struct efi_resetsystem)
>>>>
>>>> +#define EFI_RUNTIME_GET_SUPPORTED_MASK \
>>>> +    _IOR('p', 0x0C, unsigned int)
>>>> +
>>>>    #endif /* _DRIVERS_FIRMWARE_EFI_TEST_H_ */
>>>> --
>>>> 2.29.2
>>>>
>>