From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934352AbdK2RXr (ORCPT ); Wed, 29 Nov 2017 12:23:47 -0500 Received: from fldsmtpe03.verizon.com ([140.108.26.142]:30144 "EHLO fldsmtpe03.verizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934332AbdK2RXo (ORCPT ); Wed, 29 Nov 2017 12:23:44 -0500 From: alexander.levin@verizon.com Cc: Mark Rutland , Dave Martin , Suzuki K Poulose , Marc Zyngier , alexander.levin@verizon.com X-Host: endeavour.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 3.18 09/16] arm: KVM: Survive unknown traps from guests Thread-Topic: [PATCH AUTOSEL for 3.18 09/16] arm: KVM: Survive unknown traps from guests Thread-Index: AQHTaTad1jifppjf00WUSV9OzVJU1A== Date: Wed, 29 Nov 2017 17:22:21 +0000 Message-ID: <20171129172213.29007-9-alexander.levin@verizon.com> References: <20171129172213.29007-1-alexander.levin@verizon.com> In-Reply-To: <20171129172213.29007-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vATHV85Z000863 From: Mark Rutland [ Upstream commit f050fe7a9164945dd1c28be05bf00e8cfb082ccf ] 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 Signed-off-by: Sasha Levin --- 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 816db0bf2dd8..151464c6bfdb 100644 --- a/arch/arm/include/asm/kvm_arm.h +++ b/arch/arm/include/asm/kvm_arm.h @@ -208,6 +208,7 @@ #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 (1U << 0) diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c index a96a8043277c..b6ac50b85d72 100644 --- a/arch/arm/kvm/handle_exit.c +++ b/arch/arm/kvm/handle_exit.c @@ -98,7 +98,19 @@ 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, @@ -120,13 +132,6 @@ 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]; } -- 2.11.0