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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 A9C72CA9EAE for ; Tue, 29 Oct 2019 12:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D49821721 for ; Tue, 29 Oct 2019 12:40:18 +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="KnyYMMfR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732323AbfJ2MkR (ORCPT ); Tue, 29 Oct 2019 08:40:17 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:54094 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726858AbfJ2MkR (ORCPT ); Tue, 29 Oct 2019 08:40:17 -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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=sMcCsiPZroEcuV8OSVTJGo4oXf0H1fQaUisPb3xX7L8=; b=KnyYMMfRnAFyBc2hjQAOkZ1Ai pITPlePXil77rCv1X/hxMOgpBLXAXV0JrtL3VwKyl9l4T1zvUg7L+kqLs91pWMH0VyxFEsbXFlHZR IyHXs7ZNFAK2i2e+3Q8hBzD8AHG64LyO7H3VuTQvynBLUw4X6LWPw7jeHwPEVM8QvARYSN1YDMNi+ JsHg5NVOED7Oxxyh9lDXZLkJpDDn1tPrKpEJKNq3+qyS62yAgroqEzriILDOPof6ms48gX4AGdmN5 MGdW8Tk5qIcVrMXu4F+bcSKSjcaX3ZRJRg07oT7RtllhE7UpwUvFLN3TZNw6XZBPvNtNso4eu7KXD cok5eK38A==; 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 1iPQmv-0000x4-1h; Tue, 29 Oct 2019 12:39:53 +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 630913040CB; Tue, 29 Oct 2019 13:38:48 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 26FAC20D7FF19; Tue, 29 Oct 2019 13:39:49 +0100 (CET) Date: Tue, 29 Oct 2019 13:39:49 +0100 From: Peter Zijlstra To: "Kirill A. Shutemov" Cc: Dan Williams , Mike Rapoport , Linux Kernel Mailing List , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Dave Hansen , James Bottomley , Steven Rostedt , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Linux API , linux-mm , the arch/x86 maintainers , Mike Rapoport , thomas.lendacky@amd.com Subject: AMD TLB errata, (Was: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings) Message-ID: <20191029123949.GL4114@hirez.programming.kicks-ass.net> References: <1572171452-7958-1-git-send-email-rppt@kernel.org> <1572171452-7958-2-git-send-email-rppt@kernel.org> <20191028123124.ogkk5ogjlamvwc2s@box> <20191028130018.GA7192@rapoport-lnx> <20191028131623.zwuwguhm4v4s5imh@box> <20191029064318.s4n4gidlfjun3d47@box> <20191029085602.GI4114@hirez.programming.kicks-ass.net> <20191029110024.yjytp22lhd2vekrv@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191029110024.yjytp22lhd2vekrv@box> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 29, 2019 at 02:00:24PM +0300, Kirill A. Shutemov wrote: > On Tue, Oct 29, 2019 at 09:56:02AM +0100, Peter Zijlstra wrote: > > On Tue, Oct 29, 2019 at 09:43:18AM +0300, Kirill A. Shutemov wrote: > > > But some CPUs don't like to have two TLB entries for the same memory with > > > different sizes at the same time. See for instance AMD erratum 383. > > > > > > Getting it right would require making the range not present, flush TLB and > > > only then install huge page. That's what we do for userspace. > > > > > > It will not fly for the direct mapping. There is no reasonable way to > > > exclude other CPU from accessing the range while it's not present (call > > > stop_machine()? :P). Moreover, the range may contain the code that doing > > > the collapse or data required for it... > > > > > > BTW, looks like current __split_large_page() in pageattr.c is susceptible > > > to the errata. Maybe we can get away with the easy way... > > > > As you write above, there is just no way we can have a (temporary) hole > > in the direct map. > > > > We are careful about that other errata, and make sure both translations > > are identical wrt everything else. > > It's not clear if it is enough to avoid the issue. "under a highly specific > and detailed set of conditions" is not very specific set of conditions :P Yeah, I know ... :/ Tom is there any chance you could shed a little more light on that errata?