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

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Message-ID: <b1d8c534-8b47-5653-cf52-71ad5323ef14@gmx.de>
Date:   Mon, 30 Nov 2020 10:17:08 +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 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.

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
>>