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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 AB23BC0044B for ; Mon, 1 Oct 2018 15:49:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F97C20C0A for ; Mon, 1 Oct 2018 15:49:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F97C20C0A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726239AbeJAW11 (ORCPT ); Mon, 1 Oct 2018 18:27:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38880 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726156AbeJAW11 (ORCPT ); Mon, 1 Oct 2018 18:27:27 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D9BE5307C712; Mon, 1 Oct 2018 15:49:01 +0000 (UTC) Received: from [10.36.117.216] (ovpn-117-216.ams2.redhat.com [10.36.117.216]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9530E10027CE; Mon, 1 Oct 2018 15:48:58 +0000 (UTC) Subject: Re: [PATCH v6 4/7] KVM: x86: hyperv: keep track of mismatched VP indexes To: Vitaly Kuznetsov , Roman Kagan Cc: kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "Michael Kelley (EOSG)" , Mohammed Gamal , Cathy Avery , Wanpeng Li , linux-kernel@vger.kernel.org References: <20180926170259.29796-1-vkuznets@redhat.com> <20180926170259.29796-5-vkuznets@redhat.com> <20180927075911.GB4186@rkaganb.sw.ru> <87sh1vfge0.fsf@vitty.brq.redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0f UGFvbG8gQm9uemluaSA8Ym9uemluaUBnbnUub3JnPsLBTQQTAQIAIwUCVEJ7AwIbAwcLCQgH AwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEH4VEAzNNmmxNcwOniaZVLsuy1lW/ntYCA0Caz0i sHpmecK8aWlvL9wpQCk4GlOX9L1emyYXZPmzIYB0IRqmSzAlZxi+A2qm9XOxs5gJ2xqMEXX5 FMtUH3kpkWWJeLqe7z0EoQdUI4EG988uv/tdZyqjUn2XJE+K01x7r3MkUSFz/HZKZiCvYuze VlS0NTYdUt5jBXualvAwNKfxEkrxeHjxgdFHjYWhjflahY7TNRmuqPM/Lx7wAuyoDjlYNE40 Z+Kun4/KjMbjgpcF4Nf3PJQR8qXI6p3so2qsSn91tY7DFSJO6v2HwFJkC2jU95wxfNmTEUZc znXahYbVOwCDJRuPrE5GKFd/XJU9u5hNtr/uYipHij01WXal2cce1S5mn1/HuM1yo1u8xdHy IupCd57EWI948e8BlhpujUCU2tzOb2iYS0kpmJ9/oLVZrOcSZCcCl2P0AaCAsj59z2kwQS9D du0WxUs8waso0Qq6tDEHo8yLCOJDzSz4oojTtWe4zsulVnWV+wu70AioemAT8S6JOtlu60C5 dHgQUD1Tp+ReXpDKXmjbASJx4otvW0qah3o6JaqO79tbDqIvncu3tewwp6c85uZd48JnIOh3 utBAu684nJakbbvZUGikJfxd887ATQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAem Vv9Yfn2PbDIbxXqLff7oyVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CR wkMHtOmzQiQ2tSLjKh/cHeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuf fAb589AJW50kkQK9VD/9QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v02 8TVAaYbIhxvDY0hUQE4r8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQ zCYHXAzwnGi8WU9iuE1P0wARAQABwsEzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EO oJy0uZggJm7gZKeJ7iUpeX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBT uiJ0bfo55SWsUNN+c9hhIX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHn plOzCXHvmdlW0i6SrMsBDl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4 HYv/7ZnASVkR5EERFF3+6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz 876SvcOb5SL5SKg9/rCBufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvr iy9enJ8kxJwhC0ECbSKFY+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y 1lJAPPSIqZKvHzGShdh8DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT /ujKaGd4vxG2Ei+MMNDmS1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO 53DliFMkVTecLptsXaesuUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: Date: Mon, 1 Oct 2018 17:48:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <87sh1vfge0.fsf@vitty.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Mon, 01 Oct 2018 15:49:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/09/2018 11:17, Vitaly Kuznetsov wrote: > Roman Kagan writes: > >> On Wed, Sep 26, 2018 at 07:02:56PM +0200, Vitaly Kuznetsov wrote: >>> In most common cases VP index of a vcpu matches its vcpu index. Userspace >>> is, however, free to set any mapping it wishes and we need to account for >>> that when we need to find a vCPU with a particular VP index. To keep search >>> algorithms optimal in both cases introduce 'num_mismatched_vp_indexes' >>> counter showing how many vCPUs with mismatching VP index we have. In case >>> the counter is zero we can assume vp_index == vcpu_idx. >>> >>> Signed-off-by: Vitaly Kuznetsov >>> --- >>> arch/x86/include/asm/kvm_host.h | 3 +++ >>> arch/x86/kvm/hyperv.c | 26 +++++++++++++++++++++++--- >>> 2 files changed, 26 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>> index 09b2e3e2cf1b..711f79f1b5e6 100644 >>> --- a/arch/x86/include/asm/kvm_host.h >>> +++ b/arch/x86/include/asm/kvm_host.h >>> @@ -781,6 +781,9 @@ struct kvm_hv { >>> u64 hv_reenlightenment_control; >>> u64 hv_tsc_emulation_control; >>> u64 hv_tsc_emulation_status; >>> + >>> + /* How many vCPUs have VP index != vCPU index */ >>> + atomic_t num_mismatched_vp_indexes; >>> }; >>> >>> enum kvm_irqchip_mode { >>> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c >>> index c8764faf783b..6a19c8e3c432 100644 >>> --- a/arch/x86/kvm/hyperv.c >>> +++ b/arch/x86/kvm/hyperv.c >>> @@ -1045,11 +1045,31 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host) >>> struct kvm_vcpu_hv *hv_vcpu = &vcpu->arch.hyperv; >>> >>> switch (msr) { >>> - case HV_X64_MSR_VP_INDEX: >>> - if (!host || (u32)data >= KVM_MAX_VCPUS) >>> + case HV_X64_MSR_VP_INDEX: { >>> + struct kvm_hv *hv = &vcpu->kvm->arch.hyperv; >>> + int vcpu_idx = kvm_vcpu_get_idx(vcpu); >>> + u32 new_vp_index = (u32)data; >>> + >>> + if (!host || new_vp_index >= KVM_MAX_VCPUS) >>> return 1; >>> - hv_vcpu->vp_index = (u32)data; >>> + >>> + if (new_vp_index == hv_vcpu->vp_index) >>> + return 0; >>> + >>> + /* >>> + * VP index is changing, increment num_mismatched_vp_indexes in >>> + * case it was equal to vcpu_idx before; on the other hand, if >>> + * the new VP index matches vcpu_idx num_mismatched_vp_indexes >>> + * needs to be decremented. >> >> It may be worth mentioning that the initial balance is provided by >> kvm_hv_vcpu_postcreate setting vp_index = vcpu_idx. >> > > Of course, yes, will update the comment in case I'll be re-submitting. /* * VP index is initialized to hv_vcpu->vp_index by * kvm_hv_vcpu_postcreate so they initially match. Now the * VP index is changing, adjust num_mismatched_vp_indexes if * it now matches or no longer matches vcpu_idx. */ ? Paolo