From patchwork Tue Jan 25 22:03:58 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12724251 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 81503C433EF for ; Tue, 25 Jan 2022 22:04:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233501AbiAYWEM (ORCPT ); Tue, 25 Jan 2022 17:04:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233536AbiAYWEA (ORCPT ); Tue, 25 Jan 2022 17:04:00 -0500 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB375C061744 for ; Tue, 25 Jan 2022 14:04:00 -0800 (PST) Received: by mail-pl1-x64a.google.com with SMTP id o9-20020a170903210900b0014b36bee5b9so3398073ple.0 for ; Tue, 25 Jan 2022 14:04:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:message-id:mime-version:subject:from:to:cc; bh=iGLX1nMTdQXwKCljS0xZ9EDrg9qdOcQaXDmOY0TVKEc=; b=RvgXeQqUhymXWW+mcLDi7Xa3qJjEV44K/VQZz/B0wiFZjNJXJIK8GuMtuu4wl1PIS1 w10EyioiJgKsyA9yFcTaBMsVH5ASrdwp8iANijZ95lmSpiuj8ktaD5DjTs5UM6bEQOEI aFQgXFBCdQB9XDBv+i5CK3aHVmnu67tmFAHgBWg6usJ3OWVNOtH+O+Uw9Z/7j9dsofGo EhBu07m7Dm8J/BGeQSGxGoShxinsp3spXh41qScQ05o/GE34LKVZ/tUKCyR4tvr+TlNk CffZW7+iikI8A7cwcCdg0EKA+cRWjIoC0oBGnZQl4EKG/rLFw7OrsvtC51F4ozS8h72V jnvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:message-id:mime-version:subject :from:to:cc; bh=iGLX1nMTdQXwKCljS0xZ9EDrg9qdOcQaXDmOY0TVKEc=; b=UjXwL6y9GLdXrz5iACNlI5qwt1nywM6nEOHYbcSi0DAeb5kFhweVaG9w46ZwYSYFQ5 azr2zqTK1SCDgAh4g9jVieubxbMQ39eMgPv5E2TobUVODovCxTGmGXIVQvY1jvgB4B8Q FF5hzTd1iUEdGoBadWJlK8HWqI/WZjd4Ciax3gd6Ttl56CEZdYiGGxDBxcIvXQIeup88 9/nsmFdgDKuD9TuAG+8/RpWEiM9/1ipC8xKv1VBipvdPJH29GxdESZ0yRtq+q28MjJTo jwCESjMJcaTpGg7cmZxD5TCC7ZmRHxH3svGnN0a48cZMT0fzKz0fSXCt8AAuAnVtlMob i1cw== X-Gm-Message-State: AOAM533LcClJuBZwn9hqjDvmGCWSRNk7ljTrxjzJqjgDYVc/2g8MT5mK aGPlm7YBGtvIKkgwMqjrlhoJTYSPmhI= X-Google-Smtp-Source: ABdhPJwe8knRJEMoWdP667Wv4h9swXHBTSVyTQxeD8SnbjpThw9hmIMUfX/XUphfz/NAsyLFqpXjGWhY3t4= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:90b:234d:: with SMTP id ms13mr5596133pjb.44.1643148240297; Tue, 25 Jan 2022 14:04:00 -0800 (PST) Reply-To: Sean Christopherson Date: Tue, 25 Jan 2022 22:03:58 +0000 Message-Id: <20220125220358.2091737-1-seanjc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.35.0.rc0.227.g00780c9af4-goog Subject: [PATCH] KVM: x86: Forcibly leave nested virt when SMM state is toggled From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+8112db3ab20e70d50c31@syzkaller.appspotmail.com Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Forcibly leave nested virtualization operation if userspace toggles SMM state via KVM_SET_VCPU_EVENTS or KVM_SYNC_X86_EVENTS. If userspace forces the vCPU out of SMM while it's post-VMXON and then injects an SMI, vmx_enter_smm() will overwrite vmx->nested.smm.vmxon and end up with both vmxon=false and smm.vmxon=false, but all other nVMX state allocated. Don't attempt to gracefully handle the transition as (a) most transitions are nonsencial, e.g. forcing SMM while L2 is running, (b) there isn't sufficient information to handle all transitions, e.g. SVM wants access to the SMRAM save state, and (c) KVM_SET_VCPU_EVENTS must precede KVM_SET_NESTED_STATE during state restore as the latter disallows putting the vCPU into L2 if SMM is active, and disallows tagging the vCPU as being post-VMXON in SMM if SMM is not active. Abuse of KVM_SET_VCPU_EVENTS manifests as a WARN and memory leak in nVMX due to failure to free vmcs01's shadow VMCS, but the bug goes far beyond just a memory leak, e.g. toggling SMM on while L2 is active puts the vCPU in an architecturally impossible state. WARNING: CPU: 0 PID: 3606 at free_loaded_vmcs arch/x86/kvm/vmx/vmx.c:2665 [inline] WARNING: CPU: 0 PID: 3606 at free_loaded_vmcs+0x158/0x1a0 arch/x86/kvm/vmx/vmx.c:2656 Modules linked in: CPU: 1 PID: 3606 Comm: syz-executor725 Not tainted 5.17.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:free_loaded_vmcs arch/x86/kvm/vmx/vmx.c:2665 [inline] RIP: 0010:free_loaded_vmcs+0x158/0x1a0 arch/x86/kvm/vmx/vmx.c:2656 Code: <0f> 0b eb b3 e8 8f 4d 9f 00 e9 f7 fe ff ff 48 89 df e8 92 4d 9f 00 Call Trace: kvm_arch_vcpu_destroy+0x72/0x2f0 arch/x86/kvm/x86.c:11123 kvm_vcpu_destroy arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 [inline] kvm_destroy_vcpus+0x11f/0x290 arch/x86/kvm/../../../virt/kvm/kvm_main.c:460 kvm_free_vcpus arch/x86/kvm/x86.c:11564 [inline] kvm_arch_destroy_vm+0x2e8/0x470 arch/x86/kvm/x86.c:11676 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1217 [inline] kvm_put_kvm+0x4fa/0xb00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1250 kvm_vm_release+0x3f/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1273 __fput+0x286/0x9f0 fs/file_table.c:311 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0xb29/0x2a30 kernel/exit.c:806 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 get_signal+0x4b0/0x28c0 kernel/signal.c:2862 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae Cc: stable@vger.kernel.org Reported-by: syzbot+8112db3ab20e70d50c31@syzkaller.appspotmail.com Signed-off-by: Sean Christopherson --- Peeking at QEMU source, AFAICT QEMU restores nested state before events, but I don't see how that can possibly work. I assume QEMU does something where it restores the "run" state first and then does a full restore? arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm/nested.c | 9 +++++---- arch/x86/kvm/svm/svm.c | 2 +- arch/x86/kvm/svm/svm.h | 2 +- arch/x86/kvm/vmx/nested.c | 1 + arch/x86/kvm/x86.c | 4 +++- 6 files changed, 12 insertions(+), 7 deletions(-) base-commit: e2e83a73d7ce66f62c7830a85619542ef59c90e4 diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 682ad02a4e58..df22b04b11c3 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1495,6 +1495,7 @@ struct kvm_x86_ops { }; struct kvm_x86_nested_ops { + void (*leave_nested)(struct kvm_vcpu *vcpu); int (*check_events)(struct kvm_vcpu *vcpu); bool (*hv_timer_pending)(struct kvm_vcpu *vcpu); void (*triple_fault)(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index cf206855ebf0..1218b5a342fc 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -983,9 +983,9 @@ void svm_free_nested(struct vcpu_svm *svm) /* * Forcibly leave nested mode in order to be able to reset the VCPU later on. */ -void svm_leave_nested(struct vcpu_svm *svm) +void svm_leave_nested(struct kvm_vcpu *vcpu) { - struct kvm_vcpu *vcpu = &svm->vcpu; + struct vcpu_svm *svm = to_svm(vcpu); if (is_guest_mode(vcpu)) { svm->nested.nested_run_pending = 0; @@ -1411,7 +1411,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, return -EINVAL; if (!(kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE)) { - svm_leave_nested(svm); + svm_leave_nested(vcpu); svm_set_gif(svm, !!(kvm_state->flags & KVM_STATE_NESTED_GIF_SET)); return 0; } @@ -1478,7 +1478,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, */ if (is_guest_mode(vcpu)) - svm_leave_nested(svm); + svm_leave_nested(vcpu); else svm->nested.vmcb02.ptr->save = svm->vmcb01.ptr->save; @@ -1532,6 +1532,7 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu) } struct kvm_x86_nested_ops svm_nested_ops = { + .leave_nested = svm_leave_nested, .check_events = svm_check_nested_events, .triple_fault = nested_svm_triple_fault, .get_nested_state_pages = svm_get_nested_state_pages, diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 6d31d357a83b..78123ed3906f 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -290,7 +290,7 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) { if (!(efer & EFER_SVME)) { - svm_leave_nested(svm); + svm_leave_nested(vcpu); svm_set_gif(svm, true); /* #GP intercept is still needed for vmware backdoor */ if (!enable_vmware_backdoor) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 47ef8f4a9358..c55d9936bb8b 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -525,7 +525,7 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb_gpa, struct vmcb *vmcb12, bool from_vmrun); -void svm_leave_nested(struct vcpu_svm *svm); +void svm_leave_nested(struct kvm_vcpu *vcpu); void svm_free_nested(struct vcpu_svm *svm); int svm_allocate_nested(struct vcpu_svm *svm); int nested_svm_vmrun(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index f235f77cbc03..7eebfdf7204f 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6771,6 +6771,7 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *)) } struct kvm_x86_nested_ops vmx_nested_ops = { + .leave_nested = vmx_leave_nested, .check_events = vmx_check_nested_events, .hv_timer_pending = nested_vmx_preemption_timer_pending, .triple_fault = nested_vmx_triple_fault, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 55518b7d3b96..22040c682d4a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4860,8 +4860,10 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, vcpu->arch.apic->sipi_vector = events->sipi_vector; if (events->flags & KVM_VCPUEVENT_VALID_SMM) { - if (!!(vcpu->arch.hflags & HF_SMM_MASK) != events->smi.smm) + if (!!(vcpu->arch.hflags & HF_SMM_MASK) != events->smi.smm) { + kvm_x86_ops.nested_ops->leave_nested(vcpu); kvm_smm_changed(vcpu, events->smi.smm); + } vcpu->arch.smi_pending = events->smi.pending;