Description: KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest
References:
 https://www.openwall.com/lists/oss-security/2021/10/25/1
 https://lore.kernel.org/linuxppc-dev/87pmrtbbdt.fsf@mpe.ellerman.id.au/T/#u
Notes:
 carnil> Fixed in 5.14.15 as well for the 5.14.y branch.
Bugs:
upstream: released (5.15-rc6) [cdeb5d7d890e14f3b70e8087e745c4a6a7d9f337]
5.10-upstream-stable: released (5.10.76) [197ec50b2df12dbfb17929eda643b16117b6f0ca]
4.19-upstream-stable: N/A "Vulnerability introduced later"
4.9-upstream-stable: N/A "Vulnerability introduced later"
sid: released (5.14.16-1)
5.10-bullseye-security: released (5.10.84-1)
4.19-buster-security: N/A "Vulnerability introduced later"
4.9-stretch-security: N/A "Vulnerability introduced later"