From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68F65C47259 for ; Fri, 1 May 2020 10:12:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4305221974 for ; Fri, 1 May 2020 10:12:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588327938; bh=FWdojJjPTloAAYOA1G94z/BC4dOQr1JzzPfiDjmSZ/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=twRhPaCNFHAImIxPnnfUWlttrcnUIulHXLEQHtebGPXLSBEgkzKHnUVrCWQZyeUQ5 D1G8DdzqyKv6NPYQr3TnGuh6R0OMQCAjSvJQTqPC+cVEhO3xeBWX9gl90tm6Uvr7GT f3OgoQCc8HIxs7gGnNdd3fhmYJ3b9EoIMH7zXtVo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728544AbgEAKMR (ORCPT ); Fri, 1 May 2020 06:12:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:37096 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728500AbgEAKMQ (ORCPT ); Fri, 1 May 2020 06:12:16 -0400 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 89C772192A; Fri, 1 May 2020 10:12:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588327935; bh=FWdojJjPTloAAYOA1G94z/BC4dOQr1JzzPfiDjmSZ/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g30UCYx5CnN7AuBqp213+FU87CU30LjAik4HXzjMnOd6cerBQdEldONUb07oKgEXp qk5BOZB8FtjtrZ3HGVE7+2NoYFAO2gpnFcgYQ4w56PtI7K+Fgolrb/IH/pwYwgmWkG nuvVsAx3LgLyFtaRZE22edXOF02HRyemXMAD0Okw= 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 1jUSeU-008J3K-08; Fri, 01 May 2020 11:12:14 +0100 From: Marc Zyngier To: Paolo Bonzini Cc: Andrew Jones , Fangrui Song , Mark Rutland , Nick Desaulniers , Will Deacon , Zenghui Yu , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org Subject: [PATCH 4/4] KVM: arm64: Fix 32bit PC wrap-around Date: Fri, 1 May 2020 11:12:04 +0100 Message-Id: <20200501101204.364798-5-maz@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200501101204.364798-1-maz@kernel.org> References: <20200501101204.364798-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: pbonzini@redhat.com, drjones@redhat.com, maskray@google.com, mark.rutland@arm.com, ndesaulniers@google.com, will@kernel.org, yuzenghui@huawei.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 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 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org In the unlikely event that a 32bit vcpu traps into the hypervisor on an instruction that is located right at the end of the 32bit range, the emulation of that instruction is going to increment PC past the 32bit range. This isn't great, as userspace can then observe this value and get a bit confused. Conversly, userspace can do things like (in the context of a 64bit guest that is capable of 32bit EL0) setting PSTATE to AArch64-EL0, set PC to a 64bit value, change PSTATE to AArch32-USR, and observe that PC hasn't been truncated. More confusion. Fix both by: - truncating PC increments for 32bit guests - sanitizing all 32bit regs every time a core reg is changed by userspace, and that PSTATE indicates a 32bit mode. Cc: stable@vger.kernel.org Acked-by: Will Deacon Signed-off-by: Marc Zyngier --- arch/arm64/kvm/guest.c | 7 +++++++ virt/kvm/arm/hyp/aarch32.c | 8 ++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 23ebe51410f0..50a279d3ddd7 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -200,6 +200,13 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) } memcpy((u32 *)regs + off, valp, KVM_REG_SIZE(reg->id)); + + if (*vcpu_cpsr(vcpu) & PSR_MODE32_BIT) { + int i; + + for (i = 0; i < 16; i++) + *vcpu_reg32(vcpu, i) = (u32)*vcpu_reg32(vcpu, i); + } out: return err; } diff --git a/virt/kvm/arm/hyp/aarch32.c b/virt/kvm/arm/hyp/aarch32.c index d31f267961e7..25c0e47d57cb 100644 --- a/virt/kvm/arm/hyp/aarch32.c +++ b/virt/kvm/arm/hyp/aarch32.c @@ -125,12 +125,16 @@ static void __hyp_text kvm_adjust_itstate(struct kvm_vcpu *vcpu) */ void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr) { + u32 pc = *vcpu_pc(vcpu); bool is_thumb; is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_AA32_T_BIT); if (is_thumb && !is_wide_instr) - *vcpu_pc(vcpu) += 2; + pc += 2; else - *vcpu_pc(vcpu) += 4; + pc += 4; + + *vcpu_pc(vcpu) = pc; + kvm_adjust_itstate(vcpu); } -- 2.26.2