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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 64B61C43144 for ; Fri, 29 Jun 2018 10:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2273721A15 for ; Fri, 29 Jun 2018 10:49:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2273721A15 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 S934069AbeF2KtD (ORCPT ); Fri, 29 Jun 2018 06:49:03 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33740 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932389AbeF2KtC (ORCPT ); Fri, 29 Jun 2018 06:49:02 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C6D69406C78F; Fri, 29 Jun 2018 10:49:01 +0000 (UTC) Received: from [10.36.116.92] (ovpn-116-92.ams2.redhat.com [10.36.116.92]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C50CB2026D68; Fri, 29 Jun 2018 10:49:00 +0000 (UTC) Subject: Re: [PATCH 2/2] KVM: X86: Implement PV send IPI support To: Vitaly Kuznetsov , Wanpeng Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <1530265876-18136-1-git-send-email-wanpengli@tencent.com> <1530265876-18136-3-git-send-email-wanpengli@tencent.com> <878t6xewei.fsf@vitty.brq.redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <878t6xewei.fsf@vitty.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 29 Jun 2018 10:49:01 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 29 Jun 2018 10:49:01 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'pbonzini@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/06/2018 12:09, Vitaly Kuznetsov wrote: >> +KVM_FEATURE_PV_SEND_IPI || 11 || guest checks this feature bit >> + || || before enabling paravirtualized >> + || || send IPIs. > In case we decide to apply this as-is we'll likely need a new feature > for PV IPI with > 64 vCPUs (or how else would the guest know if the host > is capable or not?) > Yes, it makes sense. Perhaps we can do one of the following, or both: 1) add an argument for a "base vCPU id", so that you can use the hypercall to send the IPI to CPUs 64..127, 128..191 etc. 2) have two bitmask arguments so that one hypercall handles 128 vCPUs. to remove or limit the need for the more generic hypercall. Paolo