From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCB5EC282CE for ; Thu, 11 Apr 2019 11:47:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E1F52133D for ; Thu, 11 Apr 2019 11:47:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbfDKLrN (ORCPT ); Thu, 11 Apr 2019 07:47:13 -0400 Received: from ozlabs.org ([203.11.71.1]:42943 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726830AbfDKLrN (ORCPT ); Thu, 11 Apr 2019 07:47:13 -0400 Received: by ozlabs.org (Postfix, from userid 1034) id 44fzlg195rz9sP4; Thu, 11 Apr 2019 21:47:10 +1000 (AEST) From: Michael Ellerman To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: linuxppc-dev@ozlabs.org, diana.craciun@nxp.com, msuchanek@suse.de, christophe.leroy@c-s.fr Subject: [PATCH stable v4.9 26/35] powerpc/fsl: Emulate SPRN_BUCSR register Date: Thu, 11 Apr 2019 21:46:21 +1000 Message-Id: <20190411114630.4042-27-mpe@ellerman.id.au> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190411114630.4042-1-mpe@ellerman.id.au> References: <20190411114630.4042-1-mpe@ellerman.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Diana Craciun 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 [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 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: -- 2.20.1