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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 E4C85C04E53 for ; Wed, 15 May 2019 11:05:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B60B521743 for ; Wed, 15 May 2019 11:05:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557918302; bh=DWibo/aJh4AAodUHDgO+L5KNjhDwqYb3UZ8Bd9YCGRA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xdFwT3AUrkkbKREDTNfGsn7DM1WWE54KBrN5JOYpF3+GvP9ljui7sg493fgGNn1Eo nSHtkyCelLs6RWFuSj+RpTGY7z8/C2ZNscbw6V+wJSp6dL5hYH6mwIkOUinydpQd2x vbHKZ20CMPxh5WLILxqBi1yGcdWj3J4bNsPMNWB8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726260AbfEOLFC (ORCPT ); Wed, 15 May 2019 07:05:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:34798 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728537AbfEOLE7 (ORCPT ); Wed, 15 May 2019 07:04:59 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 665EC2173C; Wed, 15 May 2019 11:04:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557918297; bh=DWibo/aJh4AAodUHDgO+L5KNjhDwqYb3UZ8Bd9YCGRA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z5CHwpLiwAoPUPBD0l9/iZs9bJ40qoD3Ev8pwJOdOdjd7rubk4wbCGGi1g4QhdrXI i9CfPNHiFE/B/mG8dZvYFEirPXIezs5YQ3I38P1VAld9FupAPAvfP3DQEE5++3CbpC bTEE6knLrg9ePFnzjITdmT+6vjeoaNZGHh5AbT28= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "linuxppc-dev@ozlabs.org, mpe@ellerman.id.au, Diana Craciun" , Michael Ellerman , Diana Craciun Subject: [PATCH 4.4 081/266] powerpc/fsl: Emulate SPRN_BUCSR register Date: Wed, 15 May 2019 12:53:08 +0200 Message-Id: <20190515090725.183169160@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090722.696531131@linuxfoundation.org> References: <20190515090722.696531131@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kvm/e500_emulate.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/powerpc/kvm/e500_emulate.c +++ b/arch/powerpc/kvm/e500_emulate.c @@ -277,6 +277,13 @@ int kvmppc_core_emulate_mtspr_e500(struc 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: