From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752806AbeBFR5N (ORCPT ); Tue, 6 Feb 2018 12:57:13 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:40964 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752680AbeBFR4x (ORCPT ); Tue, 6 Feb 2018 12:56:53 -0500 From: Marc Zyngier To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Cc: Catalin Marinas , Will Deacon , Peter Maydell , Christoffer Dall , Lorenzo Pieralisi , Mark Rutland , Robin Murphy , Ard Biesheuvel , Andrew Jones , Hanjun Guo , Jayachandran C , Jon Masters , Russell King - ARM Linux Subject: [PATCH v4 02/17] arm: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls Date: Tue, 6 Feb 2018 17:56:06 +0000 Message-Id: <20180206175621.929-3-marc.zyngier@arm.com> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20180206175621.929-1-marc.zyngier@arm.com> References: <20180206175621.929-1-marc.zyngier@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KVM doesn't follow the SMCCC when it comes to unimplemented calls, and inject an UNDEF instead of returning an error. Since firmware calls are now used for security mitigation, they are becoming more common, and the undef is counter productive. Instead, let's follow the SMCCC which states that -1 must be returned to the caller when getting an unknown function number. Cc: Tested-by: Ard Biesheuvel Signed-off-by: Marc Zyngier --- arch/arm/kvm/handle_exit.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c index cf8bf6bf87c4..a4bf0f6f024a 100644 --- a/arch/arm/kvm/handle_exit.c +++ b/arch/arm/kvm/handle_exit.c @@ -38,7 +38,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) ret = kvm_psci_call(vcpu); if (ret < 0) { - kvm_inject_undefined(vcpu); + vcpu_set_reg(vcpu, 0, ~0UL); return 1; } @@ -47,7 +47,16 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) { - kvm_inject_undefined(vcpu); + /* + * "If an SMC instruction executed at Non-secure EL1 is + * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a + * Trap exception, not a Secure Monitor Call exception [...]" + * + * We need to advance the PC after the trap, as it would + * otherwise return to the same address... + */ + vcpu_set_reg(vcpu, 0, ~0UL); + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); return 1; } -- 2.14.2