KVM: PPC: Book3s PR: Allow access to unprivileged MMCR2 register
authorThomas Huth <thuth@redhat.com>
Wed, 21 Sep 2016 13:06:45 +0000 (15:06 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 16 Oct 2016 15:36:14 +0000 (17:36 +0200)
commit418fdccd410e34e358368b5439a20dd08d75c3c2
tree4a197bbcd4009eda5179cfcc703f8d4971552b0e
parent5a4a45686a87f29aadf462c605df5f9361b56310
KVM: PPC: Book3s PR: Allow access to unprivileged MMCR2 register

commit fa73c3b25bd8d0d393dc6109a1dba3c2aef0451e upstream.

The MMCR2 register is available twice, one time with number 785
(privileged access), and one time with number 769 (unprivileged,
but it can be disabled completely). In former times, the Linux
kernel was using the unprivileged register 769 only, but since
commit 8dd75ccb571f3c92c ("powerpc: Use privileged SPR number
for MMCR2"), it uses the privileged register 785 instead.
The KVM-PR code then of course also switched to use the SPR 785,
but this is causing older guest kernels to crash, since these
kernels still access 769 instead. So to support older kernels
with KVM-PR again, we have to support register 769 in KVM-PR, too.

Fixes: 8dd75ccb571f3c92c48014b3dabd3d51a115ab41
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/powerpc/include/asm/reg.h
arch/powerpc/kvm/book3s_emulate.c