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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB7BAEEAA7E for ; Fri, 15 Sep 2023 00:39:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231160AbjIOAjy (ORCPT ); Thu, 14 Sep 2023 20:39:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229715AbjIOAjx (ORCPT ); Thu, 14 Sep 2023 20:39:53 -0400 Received: from mail.zytor.com (unknown [IPv6:2607:7c80:54:3::138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3252526A4; Thu, 14 Sep 2023 17:39:49 -0700 (PDT) Received: from [172.27.2.41] ([98.35.210.218]) (authenticated bits=0) by mail.zytor.com (8.17.1/8.17.1) with ESMTPSA id 38F0cx0w3629046 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 14 Sep 2023 17:39:00 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 38F0cx0w3629046 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2023091101; t=1694738342; bh=Yoa4ZMiBLAyDfdX9HHdeF8UrASEf6ZDgmuoMlIr4Wlk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=V/5PwyV/E8csxXz6rtYneFFVtOBWMsVzU2Mg/Wgs3Dr0XDNzkBz/ZFAw/skVnCBBu pIX81Kk5tOxjoHoHEboQ2vuQ8rbszdcv2meKkW38C4Fpsv6lbqTJOWxteQVsyxuMV+ N0x88IFTW0/iHUVnQRWy7QnRIyb+uLWCXwjVOPJcS01dEDvnV1ysdbLMRkUl8Xs89b ZcefnQDEvbvnoxJ49fMSGYwXr8lIlAANDyg1/g4z9ndf07KJSlAj5idi2GE44ZXoYe z7lFKDrHOhCcUgZ3oZxgazX52p1YHjmuUZWWY3SOVdnLUpcnAF9ptss3dUaGqF5cAN VOwKYyWEwLGSQ== Message-ID: <5cf50d76-8e18-2863-4889-70e9c18298a1@zytor.com> Date: Thu, 14 Sep 2023 17:38:57 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v10 03/38] x86/msr: Add the WRMSRNS instruction support Content-Language: en-US To: andrew.cooper3@citrix.com, Thomas Gleixner , Xin Li , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org, jiangshanlai@gmail.com References: <20230914044805.301390-1-xin3.li@intel.com> <20230914044805.301390-4-xin3.li@intel.com> <6f5678ff-f8b1-9ada-c8c7-f32cfb77263a@citrix.com> <87y1h81ht4.ffs@tglx> <7ba4ae3e-f75d-66a8-7669-b6eb17c1aa1c@citrix.com> <87v8cc1ehe.ffs@tglx> <50e96f85-66f8-2a4f-45c9-a685c757bb28@citrix.com> From: "H. Peter Anvin" In-Reply-To: <50e96f85-66f8-2a4f-45c9-a685c757bb28@citrix.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/14/23 17:33, andrew.cooper3@citrix.com wrote: > > It's an assumption about what "definitely won't" be paravirt in the future. > > XenPV stack handling is almost-FRED-like and has been for the better > part of two decades. > > You frequently complain that there's too much black magic holding XenPV > together.  A paravirt-FRED will reduce the differences vs native > substantially. > Call it "paravirtualized exception handling." In that sense, the refactoring of the exception handling to benefit FRED is definitely useful for reducing paravirtualization. The FRED-specific code is largely trivial, and presumably what you would do is to replace the FRED wrapper with a Xen wrapper and call the common handler routines. -hpa