From patchwork Tue Mar 19 08:30:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Kachhap X-Patchwork-Id: 160533 Delivered-To: patch@linaro.org Received: by 2002:ac9:18c7:0:0:0:0:0 with SMTP id i7csp3756899oce; Tue, 19 Mar 2019 01:31:22 -0700 (PDT) X-Google-Smtp-Source: APXvYqwRri6js9+pDyVEt0/RFxLcVYnTXync707wOlUuWcg46B0+qHGsssEqmkvRcJBIlUpzFkim X-Received: by 2002:a63:3244:: with SMTP id y65mr696545pgy.417.1552984282392; Tue, 19 Mar 2019 01:31:22 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1552984282; cv=none; d=google.com; s=arc-20160816; b=0yyWWOubCmJpzFtHmKC8t94xXQyWAkglVWptwKLjsA/VoIuPVysMPXxFk8YrN84KU6 o5V4Deh9DSfv90RKdilHlIJlatmzreiSHjl5BQwX0SvcRQMki+McWMIphdgyv9VX3xk9 RdJxYo4/YNM9lYxVkUBUGvBsf7GRqVbfYVTrnzUgtf3j0E8KwFChi2iIjevz4QXsBF5N Jv492U1kZryShLiKPcEu3oj9FK0XzhLZ529I9iU0NYMc/26S1ZLmqlFxUNBojbgDqfrr A02HEiIUz0GYo2vCHjrV1Jiejmh7htiev69w2UH2N6f98XB8ut2NYaKhubtfvkK8WEE5 zu0w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from; bh=yttHqopey9catRXJKAhbVKttOklLUvmT5xoITOYkqt0=; b=JSmfE7wJ9zod7Qkyw3C60Rs5M025wWQtodZnTmA1kpUCKeDaeZRZkXsr4cvKiwW/pC DGI5UGNJ+z0bqP/4A0GHCyqHW6+ko6J2OM+UMbib8vlPvsVClAz/EOtoa0fOa+Cb7rMh WnU+A+07rTUlbREQnetRH8+YCqM2oBMOOmMCRi3NeWAGZ2YXNBIyMXghszw2VH9hw/pc h7gwUSuYVqWQ2c/f6C/WlCPQd1XDVxKBFvJHhNta+dwzlM2pKicLWPDWokvkNl8BaCg4 dGosIcS+2tLaxcwrxrZAnO7DlKxBDFUpVukM0la3MyCwvFQ+2XH93HQYbm4wsEec+lln KBhw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 38si12050670pln.90.2019.03.19.01.31.21; Tue, 19 Mar 2019 01:31:22 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727521AbfCSIbU (ORCPT + 31 others); Tue, 19 Mar 2019 04:31:20 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:46968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725934AbfCSIbU (ORCPT ); Tue, 19 Mar 2019 04:31:20 -0400 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 93FFE174E; Tue, 19 Mar 2019 01:31:19 -0700 (PDT) Received: from a075553-lin.blr.arm.com (a075553-lin.blr.arm.com [10.162.0.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5BCED3F59C; Tue, 19 Mar 2019 01:31:15 -0700 (PDT) From: Amit Daniel Kachhap To: linux-arm-kernel@lists.infradead.org Cc: Christoffer Dall , Marc Zyngier , Catalin Marinas , Will Deacon , Andrew Jones , Dave Martin , Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, Kristina Martsenko , linux-kernel@vger.kernel.org, Amit Daniel Kachhap , Mark Rutland , James Morse , Julien Thierry Subject: [PATCH v7 2/10] KVM: arm64: Support runtime sysreg visibility filtering Date: Tue, 19 Mar 2019 14:00:35 +0530 Message-Id: <1552984243-7689-3-git-send-email-amit.kachhap@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1552984243-7689-1-git-send-email-amit.kachhap@arm.com> References: <1552984243-7689-1-git-send-email-amit.kachhap@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Martin Some optional features of the Arm architecture add new system registers that are not present in the base architecture. Where these features are optional for the guest, the visibility of these registers may need to depend on some runtime configuration, such as a flag passed to KVM_ARM_VCPU_INIT. For example, ZCR_EL1 and ID_AA64ZFR0_EL1 need to be hidden if SVE is not enabled for the guest, even though these registers may be present in the hardware and visible to the host at EL2. Adding special-case checks all over the place for individual registers is going to get messy as the number of conditionally- visible registers grows. In order to help solve this problem, this patch adds a new sysreg method restrictions() that can be used to hook in any needed runtime visibility checks. This method can currently return REG_NO_USER to inhibit enumeration and ioctl access to the register for userspace, and REG_NO_GUEST to inhibit runtime access by the guest using MSR/MRS. This allows a conditionally modified view of individual system registers such as the CPU ID registers, in addition to completely hiding register where appropriate. Signed-off-by: Dave Martin --- arch/arm64/kvm/sys_regs.c | 24 +++++++++++++++++++++--- arch/arm64/kvm/sys_regs.h | 13 +++++++++++++ 2 files changed, 34 insertions(+), 3 deletions(-) -- 2.7.4 diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index a5d14b5..75942f6 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1927,6 +1927,12 @@ static void perform_access(struct kvm_vcpu *vcpu, { trace_kvm_sys_access(*vcpu_pc(vcpu), params, r); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_GUEST) { + kvm_inject_undefined(vcpu); + return; + } + /* * Not having an accessor means that we have configured a trap * that we don't know how to handle. This certainly qualifies @@ -2438,6 +2444,10 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return get_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->get_user) return (r->get_user)(vcpu, r, reg, uaddr); @@ -2459,6 +2469,10 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return set_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->set_user) return (r->set_user)(vcpu, r, reg, uaddr); @@ -2515,7 +2529,8 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind) return true; } -static int walk_one_sys_reg(const struct sys_reg_desc *rd, +static int walk_one_sys_reg(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd, u64 __user **uind, unsigned int *total) { @@ -2526,6 +2541,9 @@ static int walk_one_sys_reg(const struct sys_reg_desc *rd, if (!(rd->reg || rd->get_user)) return 0; + if (restrictions(vcpu, rd) & REG_NO_USER) + return 0; + if (!copy_reg_to_user(rd, uind)) return -EFAULT; @@ -2554,9 +2572,9 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind) int cmp = cmp_sys_reg(i1, i2); /* target-specific overrides generic entry. */ if (cmp <= 0) - err = walk_one_sys_reg(i1, &uind, &total); + err = walk_one_sys_reg(vcpu, i1, &uind, &total); else - err = walk_one_sys_reg(i2, &uind, &total); + err = walk_one_sys_reg(vcpu, i2, &uind, &total); if (err) return err; diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h index 3b1bc7f..b9dd4a9 100644 --- a/arch/arm64/kvm/sys_regs.h +++ b/arch/arm64/kvm/sys_regs.h @@ -64,8 +64,15 @@ struct sys_reg_desc { const struct kvm_one_reg *reg, void __user *uaddr); int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, const struct kvm_one_reg *reg, void __user *uaddr); + + /* Return mask of REG_* runtime restriction flags */ + unsigned int (*restrictions)(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd); }; +#define REG_NO_USER (1 << 0) /* hidden from userspace ioctl interface */ +#define REG_NO_GUEST (1 << 1) /* hidden from guest */ + static inline void print_sys_reg_instr(const struct sys_reg_params *p) { /* Look, we even formatted it for you to paste into the table! */ @@ -102,6 +109,12 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r __vcpu_sys_reg(vcpu, r->reg) = r->val; } +static inline unsigned int restrictions(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *r) +{ + return unlikely(r->restrictions) ? r->restrictions(vcpu, r) : 0; +} + static inline int cmp_sys_reg(const struct sys_reg_desc *i1, const struct sys_reg_desc *i2) {