test_520_config_random_trust_cpu in ubuntu_qrt_kernel_security failed on B-4.15 /F-5.4 arm64

[Po-Hsu Lin]

Issue found on Focal 5.4.0-128.144 in cycle sru-20220919, with ARM64 only.
(Note that we have bug 1990090 fixed recently, which is asking this option to be set for all architectures with kernel > 4.9)

Test failed with:
 FAIL: test_520_config_random_trust_cpu (__main__.KernelSecurityConfigTest)
 Ensure RANDOM_TRUST_CPU is enabled (LP: #1823754)
 ----------------------------------------------------------------------
 Traceback (most recent call last):
   File "./test-kernel-security.py", line 2981, in test_520_config_random_trust_cpu
     self.assertKernelConfig('RANDOM_TRUST_CPU', expected)
   File "./test-kernel-security.py", line 231, in assertKernelConfig
     self.assertKernelConfigSet(name)
   File "./test-kernel-security.py", line 218, in assertKernelConfigSet
     '%s option was expected to be set in the kernel config' % name)
 AssertionError: RANDOM_TRUST_CPU option was expected to be set in the kernel config

 ----------------------------------------------------------------------
 Ran 1 test in 0.003s

This option was not set to y in annotations from Focal:
CONFIG_RANDOM_TRUST_CPU policy<{'amd64': 'y', 'i386': 'y', 'ppc64el': 'y', 's390x': 'y'}>

We will need to decide if we want to modify this or the test case itself.

[Po-Hsu Lin (cypressyew)]

I just checked the Jammy config, we have arm64 set to y there.

Here is the feedback from smb regarding Focal kernel:

smb:
> So RANDOM_TRUST_CPU depends on ARCH_RANDOM and that is not defined for arm* for Focal 5.4 at least.
> In jammy there is and was introduced in 5.13 with
> commit 1a50ec0b3b2e9a83f1b1245ea37a853aac2f741c
> Author: Richard Henderson <email address hidden>
> Date: Tue Jan 21 12:58:52 2020 +0000
>
> arm64: Implement archrandom.h for ARMv8.5-RNG
>
> So whatever annotation in older kernels would say, without having above patch there is no TRUST_CPU possible

Conclusion:
At least for kernel < 5.13 and arm not set would be expected.

[Po-Hsu Lin (cypressyew)]

Also affecting B-4.15

[Steve Beattie (sbeattie)]

Merged (with changes) into qrt via https://git.launchpad.net/qa-regression-testing/commit/?id=63c5ecc2c5a348f30c1daf1ad6b0f9fa1665422e