From patchwork Thu Mar 9 09:55:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 9612845 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 21759602B4 for ; Thu, 9 Mar 2017 09:57:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A621285B5 for ; Thu, 9 Mar 2017 09:57:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0DCA0285E1; Thu, 9 Mar 2017 09:57:45 +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 A54D4285B5 for ; Thu, 9 Mar 2017 09:57:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754210AbdCIJ5i (ORCPT ); Thu, 9 Mar 2017 04:57:38 -0500 Received: from foss.arm.com ([217.140.101.70]:40314 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753800AbdCIJ5e (ORCPT ); Thu, 9 Mar 2017 04:57:34 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 576C51500; Thu, 9 Mar 2017 01:56:21 -0800 (PST) Received: from on-the-bus.cambridge.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DF4EB3F3E1; Thu, 9 Mar 2017 01:56:16 -0800 (PST) From: Marc Zyngier To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Andre Przywara , Christoffer Dall , Eric Auger , Jintack Lim , Linu Cherian , Mark Rutland , Peter Maydell Subject: [PATCH 04/10] arm: KVM: Survive unknown traps from guests Date: Thu, 9 Mar 2017 09:55:33 +0000 Message-Id: <20170309095539.14512-5-marc.zyngier@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170309095539.14512-1-marc.zyngier@arm.com> References: <20170309095539.14512-1-marc.zyngier@arm.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Mark Rutland Currently we BUG() if we see a HSR.EC value we don't recognise. As configurable disables/enables are added to the architecture (controlled by RES1/RES0 bits respectively), with associated synchronous exceptions, it may be possible for a guest to trigger exceptions with classes that we don't recognise. While we can't service these exceptions in a manner useful to the guest, we can avoid bringing down the host. Per ARM DDI 0406C.c, all currently unallocated HSR EC encodings are reserved, and per ARM DDI 0487A.k_iss10775, page G6-4395, EC values within the range 0x00 - 0x2c are reserved for future use with synchronous exceptions, and EC values within the range 0x2d - 0x3f may be used for either synchronous or asynchronous exceptions. The patch makes KVM handle any unknown EC by injecting an UNDEFINED exception into the guest, with a corresponding (ratelimited) warning in the host dmesg. We could later improve on this with with a new (opt-in) exit to the host userspace. Cc: Dave Martin Cc: Suzuki K Poulose Reviewed-by: Christoffer Dall Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier --- arch/arm/include/asm/kvm_arm.h | 1 + arch/arm/kvm/handle_exit.c | 19 ++++++++++++------- 2 files changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h index e22089fb44dc..a3f0b3d50089 100644 --- a/arch/arm/include/asm/kvm_arm.h +++ b/arch/arm/include/asm/kvm_arm.h @@ -209,6 +209,7 @@ #define HSR_EC_IABT_HYP (0x21) #define HSR_EC_DABT (0x24) #define HSR_EC_DABT_HYP (0x25) +#define HSR_EC_MAX (0x3f) #define HSR_WFI_IS_WFE (_AC(1, UL) << 0) diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c index 4e40d1955e35..96af65a30d78 100644 --- a/arch/arm/kvm/handle_exit.c +++ b/arch/arm/kvm/handle_exit.c @@ -79,7 +79,19 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } +static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run) +{ + u32 hsr = kvm_vcpu_get_hsr(vcpu); + + kvm_pr_unimpl("Unknown exception class: hsr: %#08x\n", + hsr); + + kvm_inject_undefined(vcpu); + return 1; +} + static exit_handle_fn arm_exit_handlers[] = { + [0 ... HSR_EC_MAX] = kvm_handle_unknown_ec, [HSR_EC_WFI] = kvm_handle_wfx, [HSR_EC_CP15_32] = kvm_handle_cp15_32, [HSR_EC_CP15_64] = kvm_handle_cp15_64, @@ -98,13 +110,6 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) { u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu); - if (hsr_ec >= ARRAY_SIZE(arm_exit_handlers) || - !arm_exit_handlers[hsr_ec]) { - kvm_err("Unknown exception class: hsr: %#08x\n", - (unsigned int)kvm_vcpu_get_hsr(vcpu)); - BUG(); - } - return arm_exit_handlers[hsr_ec]; }