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=-20.2 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, 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 BAA4EC433F5 for ; Fri, 24 Sep 2021 12:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAF6261414 for ; Fri, 24 Sep 2021 12:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344450AbhIXM5C (ORCPT ); Fri, 24 Sep 2021 08:57:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:50730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345076AbhIXMzC (ORCPT ); Fri, 24 Sep 2021 08:55:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 839B861268; Fri, 24 Sep 2021 12:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632487855; bh=3Dsulu7ppbW/0IoQ+ds6k1avbRsBrYijcpyFPSf7VbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jP90OCkze+hyEKQSEal91sovAVoxublSjPy8MVFTaIq1Bd6NfllFbs2iyNr/8RB0G Vob/KXh7w9Of0SpOSH/HruxEF/mq8YlxwD+ehB61HSqGzjqR0x+ON5V+rSufafcY0X A4+YiGqWceM6k7twU2Uwowo3UQZzwHIs7g8PpNzM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Nitesh Narayan Lal , Paolo Bonzini , Christian Borntraeger Subject: [PATCH 5.4 06/50] KVM: remember position in kvm->vcpus array Date: Fri, 24 Sep 2021 14:43:55 +0200 Message-Id: <20210924124332.450747933@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210924124332.229289734@linuxfoundation.org> References: <20210924124332.229289734@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Radim Krčmář commit 8750e72a79dda2f665ce17b62049f4d62130d991 upstream. Fetching an index for any vcpu in kvm->vcpus array by traversing the entire array everytime is costly. This patch remembers the position of each vcpu in kvm->vcpus array by storing it in vcpus_idx under kvm_vcpu structure. Signed-off-by: Radim Krčmář Signed-off-by: Nitesh Narayan Lal Signed-off-by: Paolo Bonzini [borntraeger@de.ibm.com]: backport to 4.19 (also fits for 5.4) Signed-off-by: Christian Borntraeger Acked-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- include/linux/kvm_host.h | 11 +++-------- virt/kvm/kvm_main.c | 5 +++-- 2 files changed, 6 insertions(+), 10 deletions(-) --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -266,7 +266,8 @@ struct kvm_vcpu { struct preempt_notifier preempt_notifier; #endif int cpu; - int vcpu_id; + int vcpu_id; /* id given by userspace at creation */ + int vcpu_idx; /* index in kvm->vcpus array */ int srcu_idx; int mode; u64 requests; @@ -571,13 +572,7 @@ static inline struct kvm_vcpu *kvm_get_v static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu) { - struct kvm_vcpu *tmp; - int idx; - - kvm_for_each_vcpu(idx, tmp, vcpu->kvm) - if (tmp == vcpu) - return idx; - BUG(); + return vcpu->vcpu_idx; } #define kvm_for_each_memslot(memslot, slots) \ --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2864,7 +2864,8 @@ static int kvm_vm_ioctl_create_vcpu(stru goto unlock_vcpu_destroy; } - BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]); + vcpu->vcpu_idx = atomic_read(&kvm->online_vcpus); + BUG_ON(kvm->vcpus[vcpu->vcpu_idx]); /* Now it's all set up, let userspace reach it */ kvm_get_kvm(kvm); @@ -2874,7 +2875,7 @@ static int kvm_vm_ioctl_create_vcpu(stru goto unlock_vcpu_destroy; } - kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu; + kvm->vcpus[vcpu->vcpu_idx] = vcpu; /* * Pairs with smp_rmb() in kvm_get_vcpu. Write kvm->vcpus