[PATCH stable v4.9 30/35] powerpc/fsl: Flush branch predictor when entering KVM

Michael Ellerman
2019-04-11T11:47:18Z

From: Diana Craciun <diana.craciun@nxp.com>

commit e7aa61f47b23afbec41031bc47ca8d6cb6516abc upstream.

Switching from the guest to host is another place
where the speculative accesses can be exploited.
Flush the branch predictor when entering KVM.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kvm/bookehv_interrupts.S | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S
index 81bd8a07aa51..612b7f6a887f 100644
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -75,6 +75,10 @@
PPC_LL r1, VCPU_HOST_STACK(r4)
PPC_LL r2, HOST_R2(r1)

+START_BTB_FLUSH_SECTION
+ BTB_FLUSH(r10)
+END_BTB_FLUSH_SECTION
+
mfspr r10, SPRN_PID
lwz r8, VCPU_HOST_PID(r4)
PPC_LL r11, VCPU_SHARED(r4)
--
2.20.1