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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 C2075C43441 for ; Mon, 26 Nov 2018 17:14:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96CE220672 for ; Mon, 26 Nov 2018 17:14:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96CE220672 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 S1726918AbeK0EJh (ORCPT ); Mon, 26 Nov 2018 23:09:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49596 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726206AbeK0EJh (ORCPT ); Mon, 26 Nov 2018 23:09:37 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0DF428E3CB; Mon, 26 Nov 2018 17:14:53 +0000 (UTC) Received: from vitty.brq.redhat.com.redhat.com (unknown [10.43.2.155]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 08C3E19C7F; Mon, 26 Nov 2018 17:14:50 +0000 (UTC) From: Vitaly Kuznetsov To: Paolo Bonzini , kvm@vger.kernel.org Cc: Radim =?utf-8?B?S3LEjW3DocWZ?= , linux-kernel@vger.kernel.org, Roman Kagan , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , x86@kernel.org, "Michael Kelley \(EOSG\)" Subject: Re: [PATCH v2 3/4] x86/kvm/hyper-v: direct mode for synthetic timers In-Reply-To: References: <20181126154732.23025-1-vkuznets@redhat.com> <20181126154732.23025-4-vkuznets@redhat.com> Date: Mon, 26 Nov 2018 18:14:49 +0100 Message-ID: <8736rnlq0m.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 26 Nov 2018 17:14:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >> index 2b7a652c9fa4..b8da14cee8e5 100644 >> --- a/include/uapi/linux/kvm.h >> +++ b/include/uapi/linux/kvm.h >> @@ -975,6 +975,7 @@ struct kvm_ppc_resize_hpt { >> #define KVM_CAP_HYPERV_ENLIGHTENED_VMCS 163 >> #define KVM_CAP_EXCEPTION_PAYLOAD 164 >> #define KVM_CAP_ARM_VM_IPA_SIZE 165 >> +#define KVM_CAP_HYPERV_STIMER_DIRECT 166 > > I wonder if all these capabilities shouldn't be replaced by a single > KVM_GET_HYPERV_SUPPORTED_CPUID ioctl, or something like that. If you > can do it for 4.21, before this one cap is crystallized into userspace > API, that would be great. :) Oh, so the suggestion is to get all these features in CPUID format (leafs 0x40000001-0x4000000A at this moment - as Hyper-V encodes them) and let userspace parse them. Could work. Will take a look. Alternatively, we can go with 'something like that' and add a generalized KVM_GET_HYPERV_SUPPORTED_CAPS ioctl (returning somehthing like u64 feature, u64 parameter pair). Doing that, however, wouldn't relieve us from adding a new KVM_CAP_HYPERV_* constant for every new feature. -- Vitaly