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 0DB41C433F5 for ; Thu, 17 Mar 2022 11:48:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233126AbiCQLtl (ORCPT ); Thu, 17 Mar 2022 07:49:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232301AbiCQLtg (ORCPT ); Thu, 17 Mar 2022 07:49:36 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 752BB149240 for ; Thu, 17 Mar 2022 04:48:19 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1647517697; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=EOmvLUBIbr9zqkOIsEaWgWSiQHfKAg5TEEhFF/0BnOM=; b=mwqne6bWyXBpslp3vcIvx9yZqYZwon743EcSjmvKgG+KO5d4J146bw3yuvNJEH//Ml1W4I XVmtg5V39U/FNBzSv+ieuoNh7UoQTq675bc5sWF71Iv8U5S+Laji1qckI+ovaT3C8Da7BQ zoSZP7/H6S9uqAMtTdQVbSdz5rt7I6zFSxH/G6Zb5q8J4O4ii1/bQfRH2ES9xVLq8pqmRN JSDvZz0aD5G7BKPRJlHxANq3xATOH35b92rVe3rUUa/wYUqa0cl09Y/c6yPLHYaS1HwU1g 4I8C3+TFv/qLwk8cHhOsZIdtiZNuipB+XBkomz4SxhxSV43slUYnmhR29Hnfww== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1647517697; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=EOmvLUBIbr9zqkOIsEaWgWSiQHfKAg5TEEhFF/0BnOM=; b=a6P18OZcRlV4BGm5FM8lGjNnib5u0yXZUpaQv0cHXoIfh+suMXgA9Sg1dmvnVbnA9yxfFA eHXz9GjvHdaIIfBA== To: Dave Hansen , "Kirill A. Shutemov" , mingo@redhat.com, bp@alien8.de, luto@kernel.org, peterz@infradead.org Cc: sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com, ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com, hpa@zytor.com, jgross@suse.com, jmattson@google.com, joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org, pbonzini@redhat.com, sdeep@vmware.com, seanjc@google.com, tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv6 11/30] x86/tdx: Handle in-kernel MMIO In-Reply-To: References: <20220316020856.24435-1-kirill.shutemov@linux.intel.com> <20220316020856.24435-12-kirill.shutemov@linux.intel.com> Date: Thu, 17 Mar 2022 12:48:17 +0100 Message-ID: <87o824241q.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 16 2022 at 14:53, Dave Hansen wrote: > On 3/15/22 19:08, Kirill A. Shutemov wrote: >> In other words, even if all of the work was done to paravirtualize all >> x86 MMIO users and virtio, this approach would still be needed. There >> is essentially no way to get rid of this code. > ... >> == Patching TDX drivers == > ...> This approach will be adopted in the future, removing the bulk of >> MMIO #VEs. The #VE-based MMIO will remain serving non-virtio use cases. > > I still don't like this very much, but I can't argue with my own logic. :) > > BTW, TDX folks... I expect you to, today, start coming up with a > comprehensive list of the MMIO-induced #VE's and the reasoning why they > should or should not be paravirtualized. You're going to get grumpy > maintainers if this is done haphazardly as one-offs when users hit > performance issues. Grumpy maintainers? That's a meme. I've never seen that happen. :)