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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 63A4BC43461 for ; Thu, 8 Apr 2021 15:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2920D610A3 for ; Thu, 8 Apr 2021 15:40:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232038AbhDHPkm (ORCPT ); Thu, 8 Apr 2021 11:40:42 -0400 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:8482 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231480AbhDHPkl (ORCPT ); Thu, 8 Apr 2021 11:40:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1617896430; x=1649432430; h=date:from:to:cc:message-id:references:mime-version: in-reply-to:subject; bh=am8zyBMva1y/GwrwCj0qzUG43318Gu7tYQSpaspx+a0=; b=AYzLe3XKg3PsT1ITTAQV5C2qAoc4A4QhTWlFUc/0yIBB5QYXobhENvj+ MFenZeQq1s5ZiR3cUhtUyFP2rp3TejqePf9mEmJY30xgaNFMDLgB/MCgm Gt8Dt8mILqGsQeHBsWN/kPqGIwviu+S0vxn4fZt9S5QTHmnSbVb0KvJwm M=; X-IronPort-AV: E=Sophos;i="5.82,206,1613433600"; d="scan'208";a="100454807" Subject: Re: [PATCH 0/4] Add support for XMM fast hypercalls Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-2a-538b0bfb.us-west-2.amazon.com) ([10.43.8.2]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP; 08 Apr 2021 15:40:21 +0000 Received: from EX13D28EUC003.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-2a-538b0bfb.us-west-2.amazon.com (Postfix) with ESMTPS id BAAD8A1E3B; Thu, 8 Apr 2021 15:40:19 +0000 (UTC) Received: from u366d62d47e3651.ant.amazon.com (10.43.160.236) by EX13D28EUC003.ant.amazon.com (10.43.164.43) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 8 Apr 2021 15:40:11 +0000 Date: Thu, 8 Apr 2021 17:40:07 +0200 From: Siddharth Chandrasekaran To: Paolo Bonzini CC: Wei Liu , , , , , , , , , , , , , , , , , , Message-ID: <20210408154006.GA32315@u366d62d47e3651.ant.amazon.com> References: <20210407212926.3016-1-sidcha@amazon.de> <20210408152817.k4d4hjdqu7hsjllo@liuwe-devbox-debian-v2> <033e7d77-d640-2c12-4918-da6b5b7f4e21@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <033e7d77-d640-2c12-4918-da6b5b7f4e21@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.43.160.236] X-ClientProxiedBy: EX13D24UWB003.ant.amazon.com (10.43.161.222) To EX13D28EUC003.ant.amazon.com (10.43.164.43) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 08, 2021 at 05:30:26PM +0200, Paolo Bonzini wrote: > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > On 08/04/21 17:28, Wei Liu wrote: > > > Although the Hyper-v TLFS mentions that a guest cannot use this feature > > > unless the hypervisor advertises support for it, some hypercalls which > > > we plan on upstreaming in future uses them anyway. > > > > No, please don't do this. Check the feature bit(s) before you issue > > hypercalls which rely on the extended interface. > > Perhaps Siddharth should clarify this, but I read it as Hyper-V being > buggy and using XMM arguments unconditionally. The guest is at fault here as it expects Hyper-V to consume arguments from XMM registers for certain hypercalls (that we are working) even if we didn't expose the feature via CPUID bits. ~ Sid. Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879