From patchwork Tue Nov 22 22:40:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jiri Slaby X-Patchwork-Id: 9442297 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5E9FB605EE for ; Tue, 22 Nov 2016 22:41:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 44ECE205A4 for ; Tue, 22 Nov 2016 22:41:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 396CB205AD; Tue, 22 Nov 2016 22:41:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 79FCE206AF for ; Tue, 22 Nov 2016 22:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934921AbcKVWku (ORCPT ); Tue, 22 Nov 2016 17:40:50 -0500 Received: from mx2.suse.de ([195.135.220.15]:53319 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934917AbcKVWkq (ORCPT ); Tue, 22 Nov 2016 17:40:46 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B26AFADC4; Tue, 22 Nov 2016 22:40:40 +0000 (UTC) From: Jiri Slaby To: stable@vger.kernel.org Cc: James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Ralf Baechle , linux-mips@linux-mips.org, kvm@vger.kernel.org, Jiri Slaby Subject: [patch added to 3.12-stable] KVM: MIPS: Make ERET handle ERL before EXL Date: Tue, 22 Nov 2016 23:40:09 +0100 Message-Id: <20161122224029.29962-21-jslaby@suse.cz> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161122224029.29962-1-jslaby@suse.cz> References: <20161122224029.29962-1-jslaby@suse.cz> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: James Hogan This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit ede5f3e7b54a4347be4d8525269eae50902bd7cd upstream. The ERET instruction to return from exception is used for returning from exception level (Status.EXL) and error level (Status.ERL). If both bits are set however we should be returning from ERL first, as ERL can interrupt EXL, for example when an NMI is taken. KVM however checks EXL first. Fix the order of the checks to match the pseudocode in the instruction set manual. Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.") Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Jiri Slaby --- arch/mips/kvm/kvm_mips_emul.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c index 4cfb5bddaa9b..716285497e0e 100644 --- a/arch/mips/kvm/kvm_mips_emul.c +++ b/arch/mips/kvm/kvm_mips_emul.c @@ -254,15 +254,15 @@ enum emulation_result kvm_mips_emul_eret(struct kvm_vcpu *vcpu) struct mips_coproc *cop0 = vcpu->arch.cop0; enum emulation_result er = EMULATE_DONE; - if (kvm_read_c0_guest_status(cop0) & ST0_EXL) { + if (kvm_read_c0_guest_status(cop0) & ST0_ERL) { + kvm_clear_c0_guest_status(cop0, ST0_ERL); + vcpu->arch.pc = kvm_read_c0_guest_errorepc(cop0); + } else if (kvm_read_c0_guest_status(cop0) & ST0_EXL) { kvm_debug("[%#lx] ERET to %#lx\n", vcpu->arch.pc, kvm_read_c0_guest_epc(cop0)); kvm_clear_c0_guest_status(cop0, ST0_EXL); vcpu->arch.pc = kvm_read_c0_guest_epc(cop0); - } else if (kvm_read_c0_guest_status(cop0) & ST0_ERL) { - kvm_clear_c0_guest_status(cop0, ST0_ERL); - vcpu->arch.pc = kvm_read_c0_guest_errorepc(cop0); } else { printk("[%#lx] ERET when MIPS_SR_EXL|MIPS_SR_ERL == 0\n", vcpu->arch.pc);