From 98518c4d8728656db349f875fcbbc7c126d4c973 Mon Sep 17 00:00:00 2001 From: Diana Craciun Date: Wed, 12 Dec 2018 16:03:03 +0200 Subject: [PATCH] powerpc/fsl: Emulate SPRN_BUCSR register 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 [mpe: Tweak comment formatting] Signed-off-by: Michael Ellerman --- arch/powerpc/kvm/e500_emulate.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c index 3f8189eb56ed..fde1de08b4d7 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: -- 2.30.2