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=-7.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 311ACC4332E for ; Thu, 28 Jan 2021 16:50:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E471064E0D for ; Thu, 28 Jan 2021 16:50:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232490AbhA1Quf (ORCPT ); Thu, 28 Jan 2021 11:50:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232606AbhA1Qtv (ORCPT ); Thu, 28 Jan 2021 11:49:51 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44D85C061573 for ; Thu, 28 Jan 2021 08:49:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ei01PC0KXVkmlkz2J1SpHtwpb2od0AMC9DXG5wIgSYc=; b=QGh6COjOAmv6c6xZVwBMAD4YyO hp+w1tpe6Rz4xSi3ka+pg/S8OtpYy/edd4ZgOtaN3xMa7EXq5zl9b6Elk3817ia9JFh4wN6ukGbzl 5bA2YAYSy2b6RVFXSY21SA2IAczL6mzVNoL35noLUGYvAQ6OaVk5yFxwKuD8NHBiUnd1RxZR/dwtP w2w+8U7GwN5rm0/2ei5lAomcFlZNQWZlaqFlxTcuX43iyQQ2bBvSCm1xImuvVERvrrfMPtH0JXUD7 pquJa5xdck2ByUSb27FNO3DJQHYKekdxIhEtNvvna24wmWbd3ai6++9eOHvARw3jgvwcqSRi5lhcv 5odggkBQ==; Received: from 54-240-197-224.amazon.com ([54.240.197.224] helo=u3832b3a9db3152.ant.amazon.com) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5ATg-0006xh-JF; Thu, 28 Jan 2021 16:49:05 +0000 Message-ID: Subject: Re: [PATCH v5 15/16] KVM: Add documentation for Xen hypercall and shared_info updates From: David Woodhouse To: Paolo Bonzini , kvm@vger.kernel.org Cc: Ankur Arora , Joao Martins , Boris Ostrovsky , Sean Christopherson , graf@amazon.com, iaslan@amazon.de, pdurrant@amazon.com, aagch@amazon.com, fandree@amazon.com, hch@infradead.org Date: Thu, 28 Jan 2021 16:49:02 +0000 In-Reply-To: References: <20210111195725.4601-1-dwmw2@infradead.org> <20210111195725.4601-16-dwmw2@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-lx2w3B1o2JDNkccPNe04" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org --=-lx2w3B1o2JDNkccPNe04 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2021-01-28 at 13:18 +0100, Paolo Bonzini wrote: > My only qualm is really that the userspace API is really ugly. >=20 > Can you just have both a VM and a VCPU ioctl (so no vcpu_id to pass!),= =20 Sure, that seems like a sensible thing to do. > add a generous padding to the struct, I think I added *some* padding to the struct kvm_xen_hvm_attr which wasn't there in Joao's original. I can add more, certainly. > and just get everything out with a=20 > single ioctl without having to pass in a type? Honestly, I don't even care about reading it out except for long_mode which the kernel *does* infer for itself when the MSR is used to fill in the hypercall page. I quite like keeping them separate; they *do* get set separately, in response to different hypercalls from the guest. And the capabilities translate naturally to a given field existing or not existing; having another mapping of that to fields in a binary structure would be additional complexity. --=-lx2w3B1o2JDNkccPNe04 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q 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