On Thu, 28 Jul 2022 00:32:17 +1000, Michael Ellerman wrote:

On a bare-metal Power8 system that doesn't have an "ibm,power-rng", a
malicious QEMU and guest that ignore the absence of the
KVM_CAP_PPC_HWRNG flag, and calls H_RANDOM anyway, will dereference a
NULL pointer.

In practice all Power8 machines have an "ibm,power-rng", but let's not
rely on that, add a NULL check and early return in
powernv_get_random_real_mode().

[...]

Applied to powerpc/next.

[1/3] powerpc/powernv: Avoid crashing if rng is NULL
      https://git.kernel.org/powerpc/c/90b5d4fe0b3ba7f589c6723c6bfb559d9e83956a
[2/3] powerpc/powernv/kvm: Use darn for H_RANDOM on Power9
      https://git.kernel.org/powerpc/c/7ef3d06f1bc4a5e62273726f3dc2bd258ae1c71f
[3/3] powerpc/powernv: rename remaining rng powernv_ functions to pnv_
      https://git.kernel.org/powerpc/c/978030f054ff97d9079b35f0178e2013918fb316

cheers