From patchwork Fri Nov 4 15:14:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 13032166 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 45512C43217 for ; Fri, 4 Nov 2022 15:16:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232450AbiKDPQL (ORCPT ); Fri, 4 Nov 2022 11:16:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232470AbiKDPQD (ORCPT ); Fri, 4 Nov 2022 11:16:03 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 486F438B0 for ; Fri, 4 Nov 2022 08:15:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667574900; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tE42PNnFF/m0fEHtmSiadsyNXCXcPI2ur/gt+05bV+k=; b=dkf7btOF8dsGwpO5VRRBPeLQynq/DXHlr4WDeNQhkjLmyB+Jq1VZTg7IC/toIeSuZyukoK Hio88/LuCasVKufLSJ6mrfGgP1Hu22zpNuFc4XSL08O1O2VzeZFs+VOOMJUOhvaBDtG1jX 25/EN+ifUMU2vpx9Jk3NTRHn2rVqVyE= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-596-bP32ffFeP-WFP6Kkw4XF0g-1; Fri, 04 Nov 2022 11:14:57 -0400 X-MC-Unique: bP32ffFeP-WFP6Kkw4XF0g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DDC132999B25; Fri, 4 Nov 2022 15:14:56 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6ABD2C2C8D9; Fri, 4 Nov 2022 15:14:56 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Eduardo Habkost , Marcel Apfelbaum , =?utf-8?q?Philippe_Mathieu-D?= =?utf-8?q?aud=C3=A9?= , Yanan Wang , kvm@vger.kernel.org, Emanuele Giuseppe Esposito , David Hildenbrand Subject: [RFC PATCH 2/3] KVM: keep track of running vcpu ioctls Date: Fri, 4 Nov 2022 11:14:53 -0400 Message-Id: <20221104151454.136551-3-eesposit@redhat.com> In-Reply-To: <20221104151454.136551-1-eesposit@redhat.com> References: <20221104151454.136551-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Just as in kvm-all.c, introduce per-vcpu QemuLockCnt to keep track when vcpus are executing an ioctl. Keep a per-vcpu lock to minimize cache line bouncing. The kvm listener will then use the lock to prevent new ioctls from running when modifying memslots. Signed-off-by: David Hildenbrand Signed-off-by: Emanuele Giuseppe Esposito --- accel/kvm/kvm-all.c | 14 ++++++++++++++ hw/core/cpu-common.c | 2 ++ include/hw/core/cpu.h | 3 +++ 3 files changed, 19 insertions(+) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index 099d7bda56..48cdf1fecd 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -2811,6 +2811,18 @@ static void kvm_eat_signals(CPUState *cpu) } while (sigismember(&chkset, SIG_IPI)); } +static void kvm_cpu_set_in_ioctl(CPUState *cpu, bool in_ioctl) +{ + if (unlikely(qemu_mutex_iothread_locked())) { + return; + } + if (in_ioctl) { + qemu_lockcnt_inc(&cpu->in_ioctl_lock); + } else { + qemu_lockcnt_dec(&cpu->in_ioctl_lock); + } +} + static void kvm_set_in_ioctl(bool in_ioctl) { if (likely(qemu_mutex_iothread_locked())) { @@ -3049,7 +3061,9 @@ int kvm_vcpu_ioctl(CPUState *cpu, int type, ...) va_end(ap); trace_kvm_vcpu_ioctl(cpu->cpu_index, type, arg); + kvm_cpu_set_in_ioctl(cpu, true); ret = ioctl(cpu->kvm_fd, type, arg); + kvm_cpu_set_in_ioctl(cpu, false); if (ret == -1) { ret = -errno; } diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c index f9fdd46b9d..8d6a4b1b65 100644 --- a/hw/core/cpu-common.c +++ b/hw/core/cpu-common.c @@ -237,6 +237,7 @@ static void cpu_common_initfn(Object *obj) cpu->nr_threads = 1; qemu_mutex_init(&cpu->work_mutex); + qemu_lockcnt_init(&cpu->in_ioctl_lock); QSIMPLEQ_INIT(&cpu->work_list); QTAILQ_INIT(&cpu->breakpoints); QTAILQ_INIT(&cpu->watchpoints); @@ -248,6 +249,7 @@ static void cpu_common_finalize(Object *obj) { CPUState *cpu = CPU(obj); + qemu_lockcnt_destroy(&cpu->in_ioctl_lock); qemu_mutex_destroy(&cpu->work_mutex); } diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index f9b58773f7..07852b2a3c 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -397,6 +397,9 @@ struct CPUState { uint32_t kvm_fetch_index; uint64_t dirty_pages; + /* kvm only for now: CPU is in kvm_vcpu_ioctl() (esp. KVM_RUN) */ + QemuLockCnt in_ioctl_lock; + /* Used for events with 'vcpu' and *without* the 'disabled' properties */ DECLARE_BITMAP(trace_dstate_delayed, CPU_TRACE_DSTATE_MAX_EVENTS); DECLARE_BITMAP(trace_dstate, CPU_TRACE_DSTATE_MAX_EVENTS);