From patchwork Thu Jun 4 13:33:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11587969 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E1E181392 for ; Thu, 4 Jun 2020 13:34:23 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B425620772 for ; Thu, 4 Jun 2020 13:34:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="rjI2SPUu"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="YR6CZ4In" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B425620772 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FT9JgH73+EeN6jtdY8qBUrqWCNXfiMl9jrH8wepwI08=; b=rjI2SPUuPnkEL+ r0FPlGrkGJiTo4XkP3eUavOh+7CXbO1Ur0eTMwr1veU/PnCcd4NtscsYyRVCFtAceZngMFXSqE3hu FbuAunFKzcGiU+XZBV+w9otsxGMSb6HEZdi2hYrAyaPI5/4qFlRPJJMWOTlJiiDeJ8PTOxca7WyNp uro65CSdFWpg/9rCRzCSUshbVkK1+lI0SfbVknkt/G/0YM1bVXj2IOMVbNNGPsdZak5A6tmMbCIZa y+740rwc+Utx8teTKnmOk7jPAMTXLUbxatiwwcAUirUGO7PLCzrBeqfrx9gr2OyQFleVbX3BjNrJb XhZNid4IcK/7E7X2EL7A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jgq0f-0000dD-1q; Thu, 04 Jun 2020 13:34:17 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jgq0U-0000PX-3L for linux-arm-kernel@lists.infradead.org; Thu, 04 Jun 2020 13:34:07 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B0BDC207F5; Thu, 4 Jun 2020 13:34:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591277645; bh=oTpdh0V2Z95uY3LBT8s4QiNnX2wWztmbveBiUjivoGs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YR6CZ4InhWsUIB0fnTVAgtFWHZM0Q9V817LIfrnpJkEIN3cbTWbaHSqpkaGScFNAF dKit3INlFzUfog/sqPThe1V17GKxiCOkAU+HJ0Mj9RSzznP/Zn8zAOQKvR/mHDmhIa 6qEZ+dO3rA3gYktLJj6oAvywWHIrYTn7S/Cnk4OM= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jgq0S-000G3O-6u; Thu, 04 Jun 2020 14:34:04 +0100 From: Marc Zyngier To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/3] KVM: arm64: Save the host's PtrAuth keys in non-preemptible context Date: Thu, 4 Jun 2020 14:33:52 +0100 Message-Id: <20200604133354.1279412-2-maz@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200604133354.1279412-1-maz@kernel.org> References: <20200604133354.1279412-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, kernel-team@android.com, stable@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200604_063406_178023_AF108708 X-CRM114-Status: GOOD ( 16.42 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kernel-team@android.com, Suzuki K Poulose , Catalin Marinas , stable@vger.kernel.org, James Morse , Will Deacon , Julien Thierry Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org When using the PtrAuth feature in a guest, we need to save the host's keys before allowing the guest to program them. For that, we dump them in a per-CPU data structure (the so called host context). But both call sites that do this are in preemptible context, which may end up in disaster should the vcpu thread get preempted before reentering the guest. Instead, save the keys eagerly on each vcpu_load(). This has an increased overhead, but is at least safe. Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier Reviewed-by: Mark Rutland --- arch/arm64/include/asm/kvm_emulate.h | 6 ------ arch/arm64/kvm/arm.c | 18 +++++++++++++++++- arch/arm64/kvm/handle_exit.c | 19 ++----------------- 3 files changed, 19 insertions(+), 24 deletions(-) diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index a30b4eec7cb4..977843e4d5fb 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -112,12 +112,6 @@ static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu) vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK); } -static inline void vcpu_ptrauth_setup_lazy(struct kvm_vcpu *vcpu) -{ - if (vcpu_has_ptrauth(vcpu)) - vcpu_ptrauth_disable(vcpu); -} - static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu) { return vcpu->arch.vsesr_el2; diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index d6988401c22a..152049c5055d 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -337,6 +337,12 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) preempt_enable(); } +#define __ptrauth_save_key(regs, key) \ +({ \ + regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \ + regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \ +}) + void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { int *last_ran; @@ -370,7 +376,17 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) else vcpu_set_wfx_traps(vcpu); - vcpu_ptrauth_setup_lazy(vcpu); + if (vcpu_has_ptrauth(vcpu)) { + struct kvm_cpu_context *ctxt = vcpu->arch.host_cpu_context; + + __ptrauth_save_key(ctxt->sys_regs, APIA); + __ptrauth_save_key(ctxt->sys_regs, APIB); + __ptrauth_save_key(ctxt->sys_regs, APDA); + __ptrauth_save_key(ctxt->sys_regs, APDB); + __ptrauth_save_key(ctxt->sys_regs, APGA); + + vcpu_ptrauth_disable(vcpu); + } } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index eb194696ef62..065251efa2e6 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -162,31 +162,16 @@ static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } -#define __ptrauth_save_key(regs, key) \ -({ \ - regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \ - regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \ -}) - /* * Handle the guest trying to use a ptrauth instruction, or trying to access a * ptrauth register. */ void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu) { - struct kvm_cpu_context *ctxt; - - if (vcpu_has_ptrauth(vcpu)) { + if (vcpu_has_ptrauth(vcpu)) vcpu_ptrauth_enable(vcpu); - ctxt = vcpu->arch.host_cpu_context; - __ptrauth_save_key(ctxt->sys_regs, APIA); - __ptrauth_save_key(ctxt->sys_regs, APIB); - __ptrauth_save_key(ctxt->sys_regs, APDA); - __ptrauth_save_key(ctxt->sys_regs, APDB); - __ptrauth_save_key(ctxt->sys_regs, APGA); - } else { + else kvm_inject_undefined(vcpu); - } } /*