Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D813C61DA4 for ; Fri, 27 Jan 2023 11:33:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233703AbjA0LdS (ORCPT ); Fri, 27 Jan 2023 06:33:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233697AbjA0Lck (ORCPT ); Fri, 27 Jan 2023 06:32:40 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D17506BBCA; Fri, 27 Jan 2023 03:31:14 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 578EC169E; Fri, 27 Jan 2023 03:31:13 -0800 (PST) Received: from e122027.cambridge.arm.com (e122027.cambridge.arm.com [10.1.35.16]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 55A0F3F64C; Fri, 27 Jan 2023 03:30:29 -0800 (PST) From: Steven Price To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Steven Price , Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev Subject: [RFC PATCH 19/28] KVM: arm64: Validate register access for a Realm VM Date: Fri, 27 Jan 2023 11:29:23 +0000 Message-Id: <20230127112932.38045-20-steven.price@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230127112932.38045-1-steven.price@arm.com> References: <20230127112248.136810-1-suzuki.poulose@arm.com> <20230127112932.38045-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The RMM only allows setting the lower GPRS (x0-x7) and PC for a realm guest. Check this in kvm_arm_set_reg() so that the VMM can receive a suitable error return if other registers are accessed. Signed-off-by: Steven Price --- arch/arm64/kvm/guest.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 5626ddb540ce..93468bbfb50e 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -768,12 +768,38 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) return kvm_arm_sys_reg_get_reg(vcpu, reg); } +/* + * The RMI ABI only enables setting the lower GPRs (x0-x7) and PC. + * All other registers are reset to architectural or otherwise defined reset + * values by the RMM + */ +static bool validate_realm_set_reg(struct kvm_vcpu *vcpu, + const struct kvm_one_reg *reg) +{ + u64 off = core_reg_offset_from_id(reg->id); + + if ((reg->id & KVM_REG_ARM_COPROC_MASK) != KVM_REG_ARM_CORE) + return false; + + switch (off) { + case KVM_REG_ARM_CORE_REG(regs.regs[0]) ... + KVM_REG_ARM_CORE_REG(regs.regs[7]): + case KVM_REG_ARM_CORE_REG(regs.pc): + return true; + } + + return false; +} + int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) { /* We currently use nothing arch-specific in upper 32 bits */ if ((reg->id & ~KVM_REG_SIZE_MASK) >> 32 != KVM_REG_ARM64 >> 32) return -EINVAL; + if (kvm_is_realm(vcpu->kvm) && !validate_realm_set_reg(vcpu, reg)) + return -EINVAL; + switch (reg->id & KVM_REG_ARM_COPROC_MASK) { case KVM_REG_ARM_CORE: return set_core_reg(vcpu, reg); case KVM_REG_ARM_FW: -- 2.34.1