[SRU][H][F][PATCH 0/2] KVM: Provide a secure guest indication (LP: 1933173)

[frank.heimes at canonical.com]

BugLink: https://bugs.launchpad.net/bugs/1933173

SRU Justification:

[Impact]

* It is difficult for customers to identify if a KVM guest on s390x runs in secure execution more or not.
  Hence several requests came up that asked about providing a better indication.

* If the mode is not known, one may venture oneself into deceptive security.

* Patches that allow a better indication via 'prot_virt_host' using the sysfs firmware interface were added to upstream kernel 5.13.

* Secure execution was initially introduced in Ubuntu with focal / 20.04, hence this request to SRU.

[Fix]

* 37564ed834aca26993b77b9b2a0119ec1ba6e00c 37564ed834ac "s390/uv: add prot virt guest/host indication files"

* df2e400e07ad53a582ee934ce8384479d5ddf48b df2e400e07ad "s390/uv: fix prot virt host indication compilation"

[Test Case]

* A z15 or LinuxONE III LPAR is needed that runs KVM in secure execution.

* Have a look for the 'prot_virt_host' key at the sysfs firmware interface
  '1' indicates that the ultravisor is active and that the guest is running protected (in secure execution mode).

[Regression Potential]

* The patch is s390x specific and modifies file arch/s390/kernel/uv.c only.

* An entirely new new function 'uv_is_prot_virt_guest' was added and initialized and used in uv_info_init,
  hence the regression risk in existing code is rather small.

* However, in case the initialization was done errornously the indication might be wrong,
  maybe showing that the system is not protected in the way it should be (wrong indication).

* More general code deficiencies in these two functions will be largely indicated by the test compiles.

* But the code was already tested based on kernel 5.13 - and for SRU-ing a cherry-pick of the patches was sufficient,
  hence the exact same code as in 5.13 is used.

* Further tests of the SRU kernels (5.11 and 5.4) can be done based on the test kernel available from the PPA (see below).

[Other]

* Patches are upstream accepted with since 5.13-rc1.

* Request was to add the patches to focal / 20.04.

* To avoid potential regressions on upgrades, the patches need to be added to hirsute / 20.10, too.

Janosch Frank (2):
  s390/uv: add prot virt guest/host indication files
  s390/uv: fix prot virt host indication compilation

 arch/s390/kernel/uv.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

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2.25.1