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authorDiana Craciun <diana.craciun@nxp.com>2019-04-11 21:46:21 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-17 08:36:42 +0200
commita1101a6297c97c126c485d2f5209547bbbb8b332 (patch)
treea5c69b7230519baf9812aad5676ccfb0514637b2
parent1eb1ddbdf5c019d90c690495dc545696c86ed3ce (diff)
powerpc/fsl: Emulate SPRN_BUCSR register
commit 98518c4d8728656db349f875fcbbc7c126d4c973 upstream. In order to flush the branch predictor the guest kernel performs writes to the BUCSR register which is hypervisor privilleged. However, the branch predictor is flushed at each KVM entry, so the branch predictor has been already flushed, so just return as soon as possible to guest. Signed-off-by: Diana Craciun <diana.craciun@nxp.com> [mpe: Tweak comment formatting] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--arch/powerpc/kvm/e500_emulate.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
index 990db69a1d0b..fa88f641ac03 100644
--- a/arch/powerpc/kvm/e500_emulate.c
+++ b/arch/powerpc/kvm/e500_emulate.c
@@ -277,6 +277,13 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
vcpu->arch.pwrmgtcr0 = spr_val;
break;
+ case SPRN_BUCSR:
+ /*
+ * If we are here, it means that we have already flushed the
+ * branch predictor, so just return to guest.
+ */
+ break;
+
/* extra exceptions */
#ifdef CONFIG_SPE_POSSIBLE
case SPRN_IVOR32: