Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753431AbcKYJEn (ORCPT ); Fri, 25 Nov 2016 04:04:43 -0500 Received: from mx2.suse.de ([195.135.220.15]:45259 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751164AbcKYIa6 (ORCPT ); Fri, 25 Nov 2016 03:30:58 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, 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 3.12 028/127] KVM: MIPS: Make ERET handle ERL before EXL Date: Fri, 25 Nov 2016 09:29:01 +0100 Message-Id: <0fca56f2a2ac129d1a9f8453c8f21ed0347b41f8.1480062521.git.jslaby@suse.cz> X-Mailer: git-send-email 2.10.2 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2144 Lines: 56 From: James Hogan 3.12-stable review patch. If anyone has any objections, please let me 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); -- 2.10.2