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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA29EC6FA82 for ; Mon, 5 Sep 2022 01:05:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231909AbiIEBFL (ORCPT ); Sun, 4 Sep 2022 21:05:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229596AbiIEBFK (ORCPT ); Sun, 4 Sep 2022 21:05:10 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2B550559A for ; Sun, 4 Sep 2022 18:05:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662339906; x=1693875906; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=4v5IJ4RBrhPA4EDHAMJWsalgSQZLpHboHn66LJ7iCvg=; b=hUyVxLi+LcGtNlyS+9ZEk+u/+dakbjWZmLiskCaOEOgAspvQhriougy3 EbBK0yplualuF62GSay0zTh2uktHhpvLwSHikHGDAIATXM10gqhmoCsKE EYr0ldmCZVkV4JJ/VDQP92/SZXBc6yIY3tPhHde0a/YraqlHB0E/y1en3 8jwBwzP2Ty20kjbuxhzJ6g9tflUOOgO4p+O1DJFiA4Ge7KjEISSVPb7T2 PiwU05Z/jDBhUNirFmhN6yz50BafQahV8eHxQLjpLGc/xwZG8dYJvPZUm z5vcMo0WpEl+mu7GtZ8cFuHi79elgiurQWjZvrHo5IYGW4zkfg1WqxBv7 A==; X-IronPort-AV: E=McAfee;i="6500,9779,10460"; a="295022918" X-IronPort-AV: E=Sophos;i="5.93,290,1654585200"; d="scan'208";a="295022918" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Sep 2022 18:05:05 -0700 X-IronPort-AV: E=Sophos;i="5.93,290,1654585200"; d="scan'208";a="675072447" Received: from yanlongs-mobl.ccr.corp.intel.com (HELO [10.255.31.230]) ([10.255.31.230]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Sep 2022 18:05:02 -0700 Message-ID: <4a92fe4a-e35a-af02-7a7d-2562405a434d@intel.com> Date: Mon, 5 Sep 2022 09:05:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.2.1 Subject: Re: [PATCH v5 3/3] i386: Add notify VM exit support To: Paolo Bonzini , Marcelo Tosatti , Richard Henderson , Eduardo Habkost , Xiaoyao Li Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org References: <20220817020845.21855-1-chenyi.qiang@intel.com> <20220817020845.21855-4-chenyi.qiang@intel.com> Content-Language: en-US From: Chenyi Qiang In-Reply-To: <20220817020845.21855-4-chenyi.qiang@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Paolo, Any comment on patch 2-3? Thanks Chenyi On 8/17/2022 10:08 AM, Chenyi Qiang wrote: > There are cases that malicious virtual machine can cause CPU stuck (due > to event windows don't open up), e.g., infinite loop in microcode when > nested #AC (CVE-2015-5307). No event window means no event (NMI, SMI and > IRQ) can be delivered. It leads the CPU to be unavailable to host or > other VMs. Notify VM exit is introduced to mitigate such kind of > attacks, which will generate a VM exit if no event window occurs in VM > non-root mode for a specified amount of time (notify window). > > A new KVM capability KVM_CAP_X86_NOTIFY_VMEXIT is exposed to user space > so that the user can query the capability and set the expected notify > window when creating VMs. The format of the argument when enabling this > capability is as follows: > Bit 63:32 - notify window specified in qemu command > Bit 31:0 - some flags (e.g. KVM_X86_NOTIFY_VMEXIT_ENABLED is set to > enable the feature.) > > Because there are some concerns, e.g. a notify VM exit may happen with > VM_CONTEXT_INVALID set in exit qualification (no cases are anticipated > that would set this bit), which means VM context is corrupted. To avoid > the false positive and a well-behaved guest gets killed, make this > feature disabled by default. Users can enable the feature by a new > machine property: > qemu -machine notify_vmexit=on,notify_window=0 ... > > A new KVM exit reason KVM_EXIT_NOTIFY is defined for notify VM exit. If > it happens with VM_INVALID_CONTEXT, hypervisor exits to user space to > inform the fatal case. Then user space can inject a SHUTDOWN event to > the target vcpu. This is implemented by injecting a sythesized triple > fault event. > > Signed-off-by: Chenyi Qiang > --- > hw/i386/x86.c | 45 +++++++++++++++++++++++++++++++++++++++++++ > include/hw/i386/x86.h | 5 +++++ > target/i386/kvm/kvm.c | 28 +++++++++++++++++++++++++++ > 3 files changed, 78 insertions(+) > > diff --git a/hw/i386/x86.c b/hw/i386/x86.c > index 050eedc0c8..1eccbd3deb 100644 > --- a/hw/i386/x86.c > +++ b/hw/i386/x86.c > @@ -1379,6 +1379,37 @@ static void machine_set_sgx_epc(Object *obj, Visitor *v, const char *name, > qapi_free_SgxEPCList(list); > } > > +static bool x86_machine_get_notify_vmexit(Object *obj, Error **errp) > +{ > + X86MachineState *x86ms = X86_MACHINE(obj); > + > + return x86ms->notify_vmexit; > +} > + > +static void x86_machine_set_notify_vmexit(Object *obj, bool value, Error **errp) > +{ > + X86MachineState *x86ms = X86_MACHINE(obj); > + > + x86ms->notify_vmexit = value; > +} > + > +static void x86_machine_get_notify_window(Object *obj, Visitor *v, > + const char *name, void *opaque, Error **errp) > +{ > + X86MachineState *x86ms = X86_MACHINE(obj); > + uint32_t notify_window = x86ms->notify_window; > + > + visit_type_uint32(v, name, ¬ify_window, errp); > +} > + > +static void x86_machine_set_notify_window(Object *obj, Visitor *v, > + const char *name, void *opaque, Error **errp) > +{ > + X86MachineState *x86ms = X86_MACHINE(obj); > + > + visit_type_uint32(v, name, &x86ms->notify_window, errp); > +} > + > static void x86_machine_initfn(Object *obj) > { > X86MachineState *x86ms = X86_MACHINE(obj); > @@ -1392,6 +1423,8 @@ static void x86_machine_initfn(Object *obj) > x86ms->oem_table_id = g_strndup(ACPI_BUILD_APPNAME8, 8); > x86ms->bus_lock_ratelimit = 0; > x86ms->above_4g_mem_start = 4 * GiB; > + x86ms->notify_vmexit = false; > + x86ms->notify_window = 0; > } > > static void x86_machine_class_init(ObjectClass *oc, void *data) > @@ -1461,6 +1494,18 @@ static void x86_machine_class_init(ObjectClass *oc, void *data) > NULL, NULL); > object_class_property_set_description(oc, "sgx-epc", > "SGX EPC device"); > + > + object_class_property_add(oc, X86_MACHINE_NOTIFY_WINDOW, "uint32_t", > + x86_machine_get_notify_window, > + x86_machine_set_notify_window, NULL, NULL); > + object_class_property_set_description(oc, X86_MACHINE_NOTIFY_WINDOW, > + "Set the notify window required by notify VM exit"); > + > + object_class_property_add_bool(oc, X86_MACHINE_NOTIFY_VMEXIT, > + x86_machine_get_notify_vmexit, > + x86_machine_set_notify_vmexit); > + object_class_property_set_description(oc, X86_MACHINE_NOTIFY_VMEXIT, > + "Enable notify VM exit"); > } > > static const TypeInfo x86_machine_info = { > diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h > index 62fa5774f8..5707329fa7 100644 > --- a/include/hw/i386/x86.h > +++ b/include/hw/i386/x86.h > @@ -85,6 +85,9 @@ struct X86MachineState { > * which means no limitation on the guest's bus locks. > */ > uint64_t bus_lock_ratelimit; > + > + bool notify_vmexit; > + uint32_t notify_window; > }; > > #define X86_MACHINE_SMM "smm" > @@ -94,6 +97,8 @@ struct X86MachineState { > #define X86_MACHINE_OEM_ID "x-oem-id" > #define X86_MACHINE_OEM_TABLE_ID "x-oem-table-id" > #define X86_MACHINE_BUS_LOCK_RATELIMIT "bus-lock-ratelimit" > +#define X86_MACHINE_NOTIFY_VMEXIT "notify-vmexit" > +#define X86_MACHINE_NOTIFY_WINDOW "notify-window" > > #define TYPE_X86_MACHINE MACHINE_TYPE_NAME("x86") > OBJECT_DECLARE_TYPE(X86MachineState, X86MachineClass, X86_MACHINE) > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index cb88ba4a00..85f11dd8d6 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -2580,6 +2580,20 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > ratelimit_set_speed(&bus_lock_ratelimit_ctrl, > x86ms->bus_lock_ratelimit, BUS_LOCK_SLICE_TIME); > } > + > + if (x86ms->notify_vmexit && > + kvm_check_extension(s, KVM_CAP_X86_NOTIFY_VMEXIT)) { > + uint64_t notify_window_flags = ((uint64_t)x86ms->notify_window << 32) | > + KVM_X86_NOTIFY_VMEXIT_ENABLED | > + KVM_X86_NOTIFY_VMEXIT_USER; > + ret = kvm_vm_enable_cap(s, KVM_CAP_X86_NOTIFY_VMEXIT, 0, > + notify_window_flags); > + if (ret < 0) { > + error_report("kvm: Failed to enable notify vmexit cap: %s", > + strerror(-ret)); > + return ret; > + } > + } > } > > return 0; > @@ -5117,6 +5131,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run) > X86CPU *cpu = X86_CPU(cs); > uint64_t code; > int ret; > + struct kvm_vcpu_events events = {}; > > switch (run->exit_reason) { > case KVM_EXIT_HLT: > @@ -5172,6 +5187,19 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run) > /* already handled in kvm_arch_post_run */ > ret = 0; > break; > + case KVM_EXIT_NOTIFY: > + ret = 0; > + if (run->notify.flags & KVM_NOTIFY_CONTEXT_INVALID) { > + warn_report("KVM: invalid context due to notify vmexit"); > + if (has_triple_fault_event) { > + events.flags |= KVM_VCPUEVENT_VALID_TRIPLE_FAULT; > + events.triple_fault.pending = true; > + ret = kvm_vcpu_ioctl(cs, KVM_SET_VCPU_EVENTS, &events); > + } else { > + ret = -1; > + } > + } > + break; > default: > fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason); > ret = -1;