"Jason A. Donenfeld" [off-list ref] writes:

On POWER8 systems that don't have ibm,power-rng available, a guest that
ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will
dereference a NULL pointer. And on machines with darn instead of
ibm,power-rng, H_RANDOM won't work at all.

This patch kills two birds with one stone, by routing H_RANDOM calls to
ppc_md.get_random_seed, and doing the real mode check inside of it.

Cc: stable@vger.kernel.org # v4.1+
Cc: Michael Ellerman <mpe@ellerman.id.au>
Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Fabiano Rosas <redacted>