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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 AD19CC43217 for ; Tue, 26 Jan 2021 19:22:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CCFE22B3B for ; Tue, 26 Jan 2021 19:22:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730882AbhAZFs2 (ORCPT ); Tue, 26 Jan 2021 00:48:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727942AbhAYMT3 (ORCPT ); Mon, 25 Jan 2021 07:19:29 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B417DC061788; Mon, 25 Jan 2021 04:18:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=W1U508PbLkgwTccNSwME/R6sQRgPyIR7/FJo2A8YTu8=; b=ajM4lt9pcZxmzaCaNYOQ5tgX52 nUbHhja1AXzBoo5MXH9nHEEE+EG15rpAKQIUw5iYjfCYXN9+fYcI9x41Ak645sUE0npOUrwInm3VM /Z047ws1ViAH8/08pF9hTVOOEVztOEGInatExkFLUqfw2iJqoUzriwkQmooewCffLV7rRcLE+b/qn 1EbKy8ItUKDTMEVqjNNDmU+lvBaQNrUDwpn4TxyKNnoJdthDIdW6O8o3UOkASatebnVxqd5/EdTeW OKxVkMzZn8GPn6LXQTXUhD8z3QANFXIUl+ddG5cgN0nKvIFVMTM0e8EV4Qv/DUc8ifcYrUgMzVnPX 2yJi1z8g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1l40oq-0006P0-RS; Mon, 25 Jan 2021 12:18:09 +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 36ABE3010C8; Mon, 25 Jan 2021 13:18:04 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1FD962B069EF9; Mon, 25 Jan 2021 13:18:04 +0100 (CET) Date: Mon, 25 Jan 2021 13:18:04 +0100 From: Peter Zijlstra To: "Xu, Like" Cc: Sean Christopherson , Andi Kleen , Kan Liang , Paolo Bonzini , eranian@google.com, kvm@vger.kernel.org, Ingo Molnar , Thomas Gleixner , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , wei.w.wang@intel.com, luwei.kang@intel.com, linux-kernel@vger.kernel.org, Like Xu Subject: Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS Message-ID: References: <20210104131542.495413-1-like.xu@linux.intel.com> <20210115182700.byczztx3vjhsq3p3@two.firstfloor.org> <076a5c7b-de2e-daf9-e6c0-5a42fb38aaa3@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <076a5c7b-de2e-daf9-e6c0-5a42fb38aaa3@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 25, 2021 at 08:07:06PM +0800, Xu, Like wrote: > So under the premise that counter cross-mapping is allowed, > how can hypercall help fix it ? Hypercall or otherwise exposing the mapping, will let the guest fix it up when it already touches the data. Which avoids the host from having to access the guest memory and is faster, no?