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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4E188C433E9 for ; Tue, 30 Mar 2021 17:00:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AFC461A08 for ; Tue, 30 Mar 2021 17:00:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232486AbhC3RAX (ORCPT ); Tue, 30 Mar 2021 13:00:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51540 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231952AbhC3RAE (ORCPT ); Tue, 30 Mar 2021 13:00:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617123603; 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=Ia9RiC+ShFIXJPCH922QqvDmZ58hKqtXlB2NuN0+x8M=; b=jMaEr3z2tzu7Yex7Dc8WkvKTJyev9ro4baa72U43JMzjmnW3tT+g6R4VG/se2F7cPJ8/iL q274IoPLN6c2hAWwdPof/A2PAxBH/8bd6GbNU8+n/iZfp2lZPu0dKl89tnC9quOfQU1N+W Aik1s+w1Rch3iwX+tgQceqLX3vH+m7o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-451-ZI0GqeLDP0GB28ZlAJTShA-1; Tue, 30 Mar 2021 13:00:01 -0400 X-MC-Unique: ZI0GqeLDP0GB28ZlAJTShA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 28023190A7A2; Tue, 30 Mar 2021 17:00:00 +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 A9BB163B8C; Tue, 30 Mar 2021 16:59:59 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: mtosatti@redhat.com, vkuznets@redhat.com, dwmw@amazon.co.uk Subject: [PATCH 1/2] KVM: x86: reduce pvclock_gtod_sync_lock critical sections Date: Tue, 30 Mar 2021 12:59:57 -0400 Message-Id: <20210330165958.3094759-2-pbonzini@redhat.com> In-Reply-To: <20210330165958.3094759-1-pbonzini@redhat.com> References: <20210330165958.3094759-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is no need to include changes to vcpu->requests into the pvclock_gtod_sync_lock critical section. The changes to the shared data structures (in pvclock_update_vm_gtod_copy) already occur under the lock. Cc: David Woodhouse Cc: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fe806e894212..0a83eff40b43 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2562,10 +2562,12 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) kvm_hv_invalidate_tsc_page(kvm); - spin_lock(&ka->pvclock_gtod_sync_lock); kvm_make_mclock_inprogress_request(kvm); + /* no guest entries from this point */ + spin_lock(&ka->pvclock_gtod_sync_lock); pvclock_update_vm_gtod_copy(kvm); + spin_unlock(&ka->pvclock_gtod_sync_lock); kvm_for_each_vcpu(i, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); @@ -2573,8 +2575,6 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) /* guest entries allowed */ kvm_for_each_vcpu(i, vcpu, kvm) kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); - - spin_unlock(&ka->pvclock_gtod_sync_lock); #endif } @@ -7740,16 +7740,14 @@ static void kvm_hyperv_tsc_notifier(void) struct kvm_arch *ka = &kvm->arch; spin_lock(&ka->pvclock_gtod_sync_lock); - pvclock_update_vm_gtod_copy(kvm); + spin_unlock(&ka->pvclock_gtod_sync_lock); kvm_for_each_vcpu(cpu, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); kvm_for_each_vcpu(cpu, vcpu, kvm) kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); - - spin_unlock(&ka->pvclock_gtod_sync_lock); } mutex_unlock(&kvm_lock); } -- 2.26.2