From patchwork Mon Jul 19 16:03:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fuad Tabba X-Patchwork-Id: 12386239 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=-21.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 804CEC07E95 for ; Mon, 19 Jul 2021 16:28:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B0E66145D for ; Mon, 19 Jul 2021 16:28:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235620AbhGSPrb (ORCPT ); Mon, 19 Jul 2021 11:47:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350259AbhGSPpq (ORCPT ); Mon, 19 Jul 2021 11:45:46 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B6A8C0613E8 for ; Mon, 19 Jul 2021 08:38:04 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id t7-20020a0562140c67b02902f36ca6afdcso14774511qvj.7 for ; Mon, 19 Jul 2021 09:03:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=X3IdqzKtSdKmEHqu0gSKjOdvCta/WPAlxOlzNq5U9KI=; b=uIH6aFAEogBPjp3JnJ8pNTafadhbYdKOoTiFg87snBwSlO47nkKZDDP+0OgB23SsPL pYWETb0wm0ULN8PK5q0FWytbFLfdGggAjYKU5gxU5joDMl09vDKWz3a12uCby8wabOJD Sohhdf4JtNvB5/Zc0yoOKHLeKVOxr5nbmtux2Aj4cN1eWopNkVAacAnCsEiWUXQ9UGP/ yKoGei+fcSWgZrKVqzWWZKGh1m0xsx46brxd4R6EAaVVn+Mdxrf9llPIzADcvJ8r8ahH v+eATGrXiMuzHkQHUOAOfOIdacdGXDQLYHt5pGRvRSMaBQHGSFjE6vNg6pxkHqWmB5Q4 N4Fw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=X3IdqzKtSdKmEHqu0gSKjOdvCta/WPAlxOlzNq5U9KI=; b=Px3jTLbmjWYmgss7H4PrvAI8+b3TaPhbHytQjx8AXda5ALar/aVullc5i8s4JPPOgp jVDA7S77JRQ2IgSmh2GQUjb2WpLmjCMWzTP5fBwDw0WrCkxjxwDASbgNZqUgy0BD/Zw4 XYcQ3mUmUpbvAwIs7DyuBL/49oQfYt2pQylUY1r/bS09lax+wY2qeDHe18yu3wooDDNn u2FR2BGVUDbfj36dGccdWOYdO5GKiXWQ3ElV27E0NUeHtyUdkjdPcwEWONhyeqVxjL9A tyMFuxZWYPb21pvIUPmhVGcLeyFis7FOPnSW1giff5jQsUgK093VfFufTPd3r221nG3Y sIpA== X-Gm-Message-State: AOAM533ae2M6GNYUsqxFSxAg7y0+Q/zTmGTkS6l4ZNMhJNr2vaAJaxIX yKxdCDJyFJjzwJTQnZvNae/o6q3UxQ== X-Google-Smtp-Source: ABdhPJxAOglNWseu0wn6j1VK16OzeLqCOGgMEktN+EBmxudy9HH20JMPvsgut3x+BTUFeB3mBdJqAyMDUQ== X-Received: from tabba.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:482]) (user=tabba job=sendgmr) by 2002:a05:6214:29e9:: with SMTP id jv9mr25278307qvb.18.1626710628711; Mon, 19 Jul 2021 09:03:48 -0700 (PDT) Date: Mon, 19 Jul 2021 17:03:31 +0100 Message-Id: <20210719160346.609914-1-tabba@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.402.g57bb445576-goog Subject: [PATCH v3 00/15] KVM: arm64: Fixed features for protected VMs From: Fuad Tabba To: kvmarm@lists.cs.columbia.edu Cc: maz@kernel.org, will@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com, christoffer.dall@arm.com, pbonzini@redhat.com, drjones@redhat.com, qperret@google.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, tabba@google.com Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi, Changes since v2 [1]: - Both trapping and setting of feature id registers are toggled by an allowed features bitmap of the feature id registers (Will) - Documentation explaining the rationale behind allowed/blocked features (Drew) - Restrict protected VM features by checking and restricting VM capabilities - Misc small fixes and tidying up (mostly Will) - Remove dependency on Will's protected VM user ABI series [2] - Rebase on 5.14-rc2 - Carried Will's acks Changes since v1 [3]: - Restrict protected VM features based on an allowed features rather than rejected ones (Drew) - Add more background describing protected KVM to the cover letter (Alex) This patch series adds support for restricting CPU features for protected VMs in KVM (pKVM) [4]. Various VM feature configurations are allowed in KVM/arm64, each requiring specific handling logic to deal with traps, context-switching and potentially emulation. Achieving feature parity in pKVM therefore requires either elevating this logic to EL2 (and substantially increasing the TCB) or continuing to trust the host handlers at EL1. Since neither of these options are especially appealing, pKVM instead limits the CPU features exposed to a guest to a fixed configuration based on the underlying hardware and which can mostly be provided straightforwardly by EL2. This series approaches that by restricting CPU features exposed to protected guests. Features advertised through feature registers are limited, which pKVM enforces by trapping register accesses and instructions associated with these features. This series is based on 5.14-rc2. You can find the applied series here [5]. Cheers, /fuad [1] https://lore.kernel.org/kvmarm/20210615133950.693489-1-tabba@google.com/ [2] https://lore.kernel.org/kvmarm/20210603183347.1695-1-will@kernel.org/ [3] https://lore.kernel.org/kvmarm/20210608141141.997398-1-tabba@google.com/ [4] Once complete, protected KVM adds the ability to create protected VMs. These protected VMs are protected from the host Linux kernel (and from other VMs), where the host does not have access to guest memory,even if compromised. Normal (nVHE) guests can still be created and run in parallel with protected VMs. Their functionality should not be affected. For protected VMs, the host should not even have access to a protected guest's state or anything that would enable it to manipulate it (e.g., vcpu register context and el2 system registers); only hyp would have that access. If the host could access that state, then it might be able to get around the protection provided. Therefore, anything that is sensitive and that would require such access needs to happen at hyp, hence the code in nvhe running only at hyp. For more details about pKVM, please refer to Will's talk at KVM Forum 2020: https://mirrors.edge.kernel.org/pub/linux/kernel/people/will/slides/kvmforum-2020-edited.pdf https://www.youtube.com/watch?v=edqJSzsDRxk [5] https://android-kvm.googlesource.com/linux/+/refs/heads/tabba/el2_fixed_feature_v3 Fuad Tabba (15): KVM: arm64: placeholder to check if VM is protected KVM: arm64: Remove trailing whitespace in comment KVM: arm64: MDCR_EL2 is a 64-bit register KVM: arm64: Fix names of config register fields KVM: arm64: Refactor sys_regs.h,c for nVHE reuse KVM: arm64: Restore mdcr_el2 from vcpu KVM: arm64: Track value of cptr_el2 in struct kvm_vcpu_arch KVM: arm64: Add feature register flag definitions KVM: arm64: Add config register bit definitions KVM: arm64: Guest exit handlers for nVHE hyp KVM: arm64: Add trap handlers for protected VMs KVM: arm64: Move sanitized copies of CPU features KVM: arm64: Trap access to pVM restricted features KVM: arm64: Handle protected guests at 32 bits KVM: arm64: Restrict protected VM capabilities arch/arm64/include/asm/cpufeature.h | 4 +- arch/arm64/include/asm/kvm_arm.h | 54 ++- arch/arm64/include/asm/kvm_asm.h | 2 +- arch/arm64/include/asm/kvm_fixed_config.h | 188 +++++++++ arch/arm64/include/asm/kvm_host.h | 15 +- arch/arm64/include/asm/kvm_hyp.h | 5 +- arch/arm64/include/asm/sysreg.h | 15 +- arch/arm64/kernel/cpufeature.c | 8 +- arch/arm64/kvm/Makefile | 2 +- arch/arm64/kvm/arm.c | 75 +++- arch/arm64/kvm/debug.c | 2 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 76 +++- arch/arm64/kvm/hyp/nvhe/Makefile | 2 +- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 2 +- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 6 - arch/arm64/kvm/hyp/nvhe/switch.c | 72 +++- arch/arm64/kvm/hyp/nvhe/sys_regs.c | 445 ++++++++++++++++++++++ arch/arm64/kvm/hyp/vhe/debug-sr.c | 2 +- arch/arm64/kvm/hyp/vhe/switch.c | 12 +- arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 2 +- arch/arm64/kvm/pkvm.c | 213 +++++++++++ arch/arm64/kvm/sys_regs.c | 34 +- arch/arm64/kvm/sys_regs.h | 31 ++ 23 files changed, 1172 insertions(+), 95 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_fixed_config.h create mode 100644 arch/arm64/kvm/hyp/nvhe/sys_regs.c create mode 100644 arch/arm64/kvm/pkvm.c base-commit: 2734d6c1b1a089fb593ef6a23d4b70903526fe0c