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 54DD0C38142 for ; Tue, 31 Jan 2023 11:00:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231674AbjAaLAa (ORCPT ); Tue, 31 Jan 2023 06:00:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231689AbjAaLAO (ORCPT ); Tue, 31 Jan 2023 06:00:14 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9AB1D47EF9; Tue, 31 Jan 2023 03:00:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=zjviUSUPr5M8hEPUfDl2kMa5y6J74xGv1mMvHMYGeQU=; b=u3V83LfwHGcN3YHWzUJSjDkE4W Rjp+BcNBTwC2wF1ciJukeW5Ghiv6xb57TSa3joTm1KuD6wdMZePGwdRqL/Qj3PC72oNM6VWY4oPbZ PPPFvGDFPmFbLwHNAxIhXNAefNDVw5afGB5qFZF6En/nPS6noPNPpOom+yz4nuvog5SdI0OmiDM91 DjdqCRajfOTnBEKABuQXka+KnKpY4g73CyMC3od5EqU/wQhhJdh6ECbuIunzr3LXwgFUoh/brpEvB YHNYRigFClK7uQcJOWxO876TQv+sqFIRJhiD4I0Hu0/RZDPDwP8b1H0cgMFAcbpinmz2MTrVZNvoE R4EsFuKw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pMoMP-00BFNS-Hw; Tue, 31 Jan 2023 10:59:34 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9924130012F; Tue, 31 Jan 2023 11:59:31 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 80E98240A5DF8; Tue, 31 Jan 2023 11:59:31 +0100 (CET) Date: Tue, 31 Jan 2023 11:59:31 +0100 From: Peter Zijlstra To: "Liang, Kan" Cc: Andi Kleen , Sean Christopherson , Ingo Molnar , Arnaldo Carvalho de Melo , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , "H. Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Jianfeng Gao , Andrew Cooper Subject: Re: [PATCH] perf/x86: KVM: Disable vPMU support on hybrid CPUs (host PMUs) Message-ID: References: <20230120004051.2043777-1-seanjc@google.com> <1dec071d-c010-cd89-9e58-d643e71e775c@linux.intel.com> <50e840ea-ce9c-9290-2187-d3ff0d9a6709@linux.intel.com> <67facb87-f835-abcd-3d1b-527531b26e52@linux.intel.com> <8eda340a-8c5d-a801-54eb-501c44a68d89@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8eda340a-8c5d-a801-54eb-501c44a68d89@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 24, 2023 at 10:31:00AM -0500, Liang, Kan wrote: > Yes, and also the CPUID leaf 0x23H support to enumerate the PMU features > of each types. Note that this is not enough or even useful. There is nothing that stops a vCPU from migrating between types at every instruction. There simply is no relation between a vCPU and a type, so knowing what a type does or does not support is useless information.