From patchwork Fri Apr 30 10:33:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chenyi Qiang X-Patchwork-Id: 12232919 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 72AD1C433B4 for ; Fri, 30 Apr 2021 10:32:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 C3A5461458 for ; Fri, 30 Apr 2021 10:32:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3A5461458 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48446 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lcQRj-0005X6-O7 for qemu-devel@archiver.kernel.org; Fri, 30 Apr 2021 06:32:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60766) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcQOs-0003mc-PT for qemu-devel@nongnu.org; Fri, 30 Apr 2021 06:29:37 -0400 Received: from mga17.intel.com ([192.55.52.151]:43719) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcQOi-0006T0-VZ for qemu-devel@nongnu.org; Fri, 30 Apr 2021 06:29:32 -0400 IronPort-SDR: B7yW7v2Ua186W4/2y9kKtX/e2fZn3L0Y+KAKndBMtE+Wkhai8EAZLdFHd1o7nAWWjqKgbDAQkc Tp+X9dKXwk1g== X-IronPort-AV: E=McAfee;i="6200,9189,9969"; a="177402333" X-IronPort-AV: E=Sophos;i="5.82,262,1613462400"; d="scan'208";a="177402333" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2021 03:29:16 -0700 IronPort-SDR: 2Xk+wjEuEzl7dZVB3LW7uNn7HTuWhMhprTkbQmhr060E7DTcOkXPwfWJDI0T1FVx/nIXPZWOJg M+VTDRFz0N4w== X-IronPort-AV: E=Sophos;i="5.82,262,1613462400"; d="scan'208";a="431374498" Received: from chenyi-pc.sh.intel.com ([10.239.159.24]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2021 03:29:14 -0700 From: Chenyi Qiang To: Paolo Bonzini , Richard Henderson , Eduardo Habkost , Marcelo Tosatti , Xiaoyao Li Subject: [PATCH v3] i386: Add ratelimit for bus locks acquired in guest Date: Fri, 30 Apr 2021 18:33:05 +0800 Message-Id: <20210430103305.28849-1-chenyi.qiang@intel.com> X-Mailer: git-send-email 2.17.1 Received-SPF: pass client-ip=192.55.52.151; envelope-from=chenyi.qiang@intel.com; helo=mga17.intel.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" A bus lock is acquired through either split locked access to writeback (WB) memory or any locked access to non-WB memory. It is typically >1000 cycles slower than an atomic operation within a cache and can also disrupts performance on other cores. Virtual Machines can exploit bus locks to degrade the performance of system. To address this kind of performance DOS attack coming from the VMs, bus lock VM exit is introduced in KVM and it can report the bus locks detected in guest. If enabled in KVM, it would exit to the userspace to let the user enforce throttling policies once bus locks acquired in VMs. The availability of bus lock VM exit can be detected through the KVM_CAP_X86_BUS_LOCK_EXIT. The returned bitmap contains the potential policies supported by KVM. The field KVM_BUS_LOCK_DETECTION_EXIT in bitmap is the only supported strategy at present. It indicates that KVM will exit to userspace to handle the bus locks. This patch adds a ratelimit on the bus locks acquired in guest as a mitigation policy. Introduce a new field "bus_lock_ratelimit" to record the limited speed of bus locks in the target VM. The user can specify it through the "bus-lock-ratelimit" as a machine property. In current implementation, the default value of the speed is 0 per second, which means no restrictions on the bus locks As for ratelimit on detected bus locks, simply set the ratelimit interval to 1s and restrict the quota of bus lock occurence to the value of "bus_lock_ratelimit". A potential alternative is to introduce the time slice as a property which can help the user achieve more precise control. The detail of Bus lock VM exit can be found in spec: https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html Signed-off-by: Chenyi Qiang --- Changes from v2: - do some rename work (bus-lock-ratelimit and BUS_LOCK_TIME_SLICE). (Eduardo) - change to register a class property at the x86_machine_class_init() and write the gettter/setter for the bus_lock_ratelimit property. (Eduardo) - add the lock to access the Ratelimit instance to avoid vcpu thread race condition. (Eduardo) - v2: https://lore.kernel.org/qemu-devel/20210420093736.17613-1-chenyi.qiang@intel.com/ Changes from RFC v1: - Remove the rip info output, as the rip can't reflect the bus lock position correctly. (Xiaoyao) - RFC v1: https://lore.kernel.org/qemu-devel/20210317084709.15605-1-chenyi.qiang@intel.com/ --- hw/i386/x86.c | 24 ++++++++++++++++++++++ include/hw/i386/x86.h | 9 +++++++++ target/i386/kvm/kvm.c | 46 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 79 insertions(+) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index ed796fe6ba..d30cf27e29 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -1246,6 +1246,23 @@ static void x86_machine_set_oem_table_id(Object *obj, const char *value, strncpy(x86ms->oem_table_id, value, 8); } +static void x86_machine_get_bus_lock_ratelimit(Object *obj, Visitor *v, + const char *name, void *opaque, Error **errp) +{ + X86MachineState *x86ms = X86_MACHINE(obj); + uint64_t bus_lock_ratelimit = x86ms->bus_lock_ratelimit; + + visit_type_uint64(v, name, &bus_lock_ratelimit, errp); +} + +static void x86_machine_set_bus_lock_ratelimit(Object *obj, Visitor *v, + const char *name, void *opaque, Error **errp) +{ + X86MachineState *x86ms = X86_MACHINE(obj); + + visit_type_uint64(v, name, &x86ms->bus_lock_ratelimit, errp); +} + static void x86_machine_initfn(Object *obj) { X86MachineState *x86ms = X86_MACHINE(obj); @@ -1256,6 +1273,7 @@ static void x86_machine_initfn(Object *obj) x86ms->pci_irq_mask = ACPI_BUILD_PCI_IRQS; x86ms->oem_id = g_strndup(ACPI_BUILD_APPNAME6, 6); x86ms->oem_table_id = g_strndup(ACPI_BUILD_APPNAME8, 8); + x86ms->bus_lock_ratelimit = 0; } static void x86_machine_class_init(ObjectClass *oc, void *data) @@ -1299,6 +1317,12 @@ static void x86_machine_class_init(ObjectClass *oc, void *data) "Override the default value of field OEM Table ID " "in ACPI table header." "The string may be up to 8 bytes in size"); + + object_class_property_add(oc, X86_MACHINE_BUS_LOCK_RATELIMIT, "uint64_t", + x86_machine_get_bus_lock_ratelimit, + x86_machine_set_bus_lock_ratelimit, NULL, NULL); + object_class_property_set_description(oc, X86_MACHINE_BUS_LOCK_RATELIMIT, + "Set the ratelimit for the bus locks acquired in VMs"); } static const TypeInfo x86_machine_info = { diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h index c09b648dff..49b130a649 100644 --- a/include/hw/i386/x86.h +++ b/include/hw/i386/x86.h @@ -74,12 +74,21 @@ struct X86MachineState { * will be translated to MSI messages in the address space. */ AddressSpace *ioapic_as; + + /* + * Ratelimit enforced on detected bus locks in guest. + * The default value of the bus_lock_ratelimit is 0 per second, + * which means no limitation on the guest's bus locks. + */ + uint64_t bus_lock_ratelimit; + RateLimit bus_lock_ratelimit_ctrl; }; #define X86_MACHINE_SMM "smm" #define X86_MACHINE_ACPI "acpi" #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 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 7fe9f52710..19b6c4a7e8 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -130,6 +130,9 @@ static bool has_msr_mcg_ext_ctl; static struct kvm_cpuid2 *cpuid_cache; static struct kvm_msr_list *kvm_feature_msrs; +#define BUS_LOCK_SLICE_TIME 1000000000ULL /* ns */ +static QemuMutex bus_lock_ratelimit_lock; + int kvm_has_pit_state2(void) { return has_pit_state2; @@ -2267,6 +2270,28 @@ int kvm_arch_init(MachineState *ms, KVMState *s) } } + if (object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) { + X86MachineState *x86ms = X86_MACHINE(ms); + + if (x86ms->bus_lock_ratelimit > 0) { + ret = kvm_check_extension(s, KVM_CAP_X86_BUS_LOCK_EXIT); + if (!(ret & KVM_BUS_LOCK_DETECTION_EXIT)) { + error_report("kvm: bus lock detection unsupported"); + return -ENOTSUP; + } + ret = kvm_vm_enable_cap(s, KVM_CAP_X86_BUS_LOCK_EXIT, 0, + KVM_BUS_LOCK_DETECTION_EXIT); + if (ret < 0) { + error_report("kvm: Failed to enable bus lock detection cap: %s", + strerror(-ret)); + return ret; + } + qemu_mutex_init(&bus_lock_ratelimit_lock); + ratelimit_set_speed(&x86ms->bus_lock_ratelimit_ctrl, x86ms->bus_lock_ratelimit, + BUS_LOCK_SLICE_TIME); + } + } + return 0; } @@ -4221,6 +4246,20 @@ void kvm_arch_pre_run(CPUState *cpu, struct kvm_run *run) } } +static void kvm_rate_limit_on_bus_lock(void) +{ + MachineState *ms = MACHINE(qdev_get_machine()); + X86MachineState *x86ms = X86_MACHINE(ms); + + qemu_mutex_lock(&bus_lock_ratelimit_lock); + uint64_t delay_ns = ratelimit_calculate_delay(&x86ms->bus_lock_ratelimit_ctrl, 1); + qemu_mutex_unlock(&bus_lock_ratelimit_lock); + + if (delay_ns) { + g_usleep(delay_ns / SCALE_US); + } +} + MemTxAttrs kvm_arch_post_run(CPUState *cpu, struct kvm_run *run) { X86CPU *x86_cpu = X86_CPU(cpu); @@ -4236,6 +4275,9 @@ MemTxAttrs kvm_arch_post_run(CPUState *cpu, struct kvm_run *run) } else { env->eflags &= ~IF_MASK; } + if (run->flags & KVM_RUN_X86_BUS_LOCK) { + kvm_rate_limit_on_bus_lock(); + } /* We need to protect the apic state against concurrent accesses from * different threads in case the userspace irqchip is used. */ @@ -4594,6 +4636,10 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run) ioapic_eoi_broadcast(run->eoi.vector); ret = 0; break; + case KVM_EXIT_X86_BUS_LOCK: + /* already handled in kvm_arch_post_run */ + ret = 0; + break; default: fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason); ret = -1;