From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754062AbdBETZb (ORCPT + 2 others); Sun, 5 Feb 2017 14:25:31 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:28049 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753992AbdBETZZ (ORCPT ); Sun, 5 Feb 2017 14:25:25 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net 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, Willy Tarreau Subject: [PATCH 3.10 026/319] KVM: MIPS: Make ERET handle ERL before EXL Date: Sun, 5 Feb 2017 20:21:04 +0100 Message-Id: <1486322467-7968-4-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322467-7968-1-git-send-email-w@1wt.eu> References: <1486322467-7968-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=latin1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: James Hogan 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: Willy Tarreau --- 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 4cfb5bd..7162854 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); -- 2.8.0.rc2.1.gbe9624a