]> git.baikalelectronics.ru Git - kernel.git/commit
KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest
authorMichael Ellerman <mpe@ellerman.id.au>
Fri, 15 Oct 2021 12:02:08 +0000 (23:02 +1100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 27 Oct 2021 07:54:28 +0000 (09:54 +0200)
commit41ec8598ffafc90f35e232c74af5b33431a5223a
tree48e9049018a1fc09ef63beaaa83c536a4fc2a178
parent9a8a44de86cdf8528e734a747480d229a94724e5
KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest

commit cdeb5d7d890e14f3b70e8087e745c4a6a7d9f337 upstream.

We call idle_kvm_start_guest() from power7_offline() if the thread has
been requested to enter KVM. We pass it the SRR1 value that was returned
from power7_idle_insn() which tells us what sort of wakeup we're
processing.

Depending on the SRR1 value we pass in, the KVM code might enter the
guest, or it might return to us to do some host action if the wakeup
requires it.

If idle_kvm_start_guest() is able to handle the wakeup, and enter the
guest it is supposed to indicate that by returning a zero SRR1 value to
us.

That was the behaviour prior to commit 7c6829b24785 ("powerpc/64s:
Reimplement book3s idle code in C"), however in that commit the
handling of SRR1 was reworked, and the zeroing behaviour was lost.

Returning from idle_kvm_start_guest() without zeroing the SRR1 value can
confuse the host offline code, causing the guest to crash and other
weirdness.

Fixes: 7c6829b24785 ("powerpc/64s: Reimplement book3s idle code in C")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015133929.832061-2-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/powerpc/kvm/book3s_hv_rmhandlers.S