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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 361EEC10F25 for ; Mon, 9 Mar 2020 20:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F7152146E for ; Mon, 9 Mar 2020 20:22:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nI31IECV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726450AbgCIUWT (ORCPT ); Mon, 9 Mar 2020 16:22:19 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:44906 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725992AbgCIUWT (ORCPT ); Mon, 9 Mar 2020 16:22:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=1IPYKY5i0WcOP6+Mj4yJxK/haVfh2zKAl1BsGlfBYoo=; b=nI31IECVSTE8x6hUOJdpZRMUn8 PMBZ94A1ZJeMRVcmZcKK1/D7DCQn+99kHR7UoTYlAQQInp/PWot3vgF/mIBFNR8sBOZtyp/hzOqfh uRlbmZpJL9fTmFixakxdQ7VCkcuI9tQhFxhQnK2Pun61Cc6eNKcsgNppD2DMOO1QWgcMNiiSFtNZI opI3w1chWcm6Uh5Fz/iWXBFjxLbLQ+dmQqb+qbtWRgO+/n2bZcV0MioIGAbt3y0QHD5JAzBU+RtJT 5ilbIDNGF566RvgE1KB1VyzJku4UxZm1i8gTMArg6REiAGEXcgKHQ4r+atYTD1DCq8M2ckTByzowl w0DD3IVw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBOum-0003m4-OA; Mon, 09 Mar 2020 20:22:16 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 35E553011E0; Mon, 9 Mar 2020 21:22:15 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1EF51214344E6; Mon, 9 Mar 2020 21:22:15 +0100 (CET) Date: Mon, 9 Mar 2020 21:22:15 +0100 From: Peter Zijlstra To: Thomas Gleixner Cc: Andy Lutomirski , Paolo Bonzini , LKML , X86 ML , kvm list , stable Subject: Re: [PATCH v2] x86/kvm: Disable KVM_ASYNC_PF_SEND_ALWAYS Message-ID: <20200309202215.GM12561@hirez.programming.kicks-ass.net> References: <87ftek9ngq.fsf@nanos.tec.linutronix.de> <87a74s9ehb.fsf@nanos.tec.linutronix.de> <87wo7v8g4j.fsf@nanos.tec.linutronix.de> <877dzu8178.fsf@nanos.tec.linutronix.de> <37440ade-1657-648b-bf72-2b8ca4ac21ce@redhat.com> <871rq199oz.fsf@nanos.tec.linutronix.de> <87d09l73ip.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d09l73ip.fsf@nanos.tec.linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 09, 2020 at 08:05:18PM +0100, Thomas Gleixner wrote: > Andy Lutomirski writes: > > I'm okay with the save/restore dance, I guess. It's just yet more > > entry crud to deal with architecture nastiness, except that this > > nastiness is 100% software and isn't Intel/AMD's fault. > > And we can do it in C and don't have to fiddle with it in the ASM > maze. Right; I'd still love to kill KVM_ASYNC_PF_SEND_ALWAYS though, even if we do the save/restore in do_nmi(). That is some wild brain melt. Also, AFAIK none of the distros are actually shipping a PREEMPT=y kernel anyway, so killing it shouldn't matter much. If people want to recover that, I'd suggest they sit down and create a sane paravirt interface for this.