From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D7A4C432E85; Fri, 24 Jul 2026 14:19:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784902763; cv=none; b=dX4kIgcFyrs3C/UjcMtqc8nhsn6nXaLOEogpPYpP6AC0h7pJXCKykhLgbioHNAWukzC37jozUKN840XRatHfIEjl65kKTB3aToeiAAUVnpZhXq5UkIuHp2hKJSmrbO1hQaOzTZdyYDU1eS1m0cpp3Ck9i8NSYc6+UDWoi3/SWpI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784902763; c=relaxed/simple; bh=10i5EvWAKrIKZG/5TYABM+/91AVrSm1aivuorzMif/c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=L9N/pRnVDJec1G4ugRLXruoiP9Ru/2XVP8tKNDnvv8JtXwnysn7ANY4XGtRgVwTE8fRAAe/fjxDLt3EE/Kk3gLdMIvaO/1OI2xqg+/frnLk5/bvUavdba1+UiuZEbbZefbnmUgyYo0GiBvUBpkFuV0YjxN7Vp0UWlLzygMcofdA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=iJgULsDP; arc=none smtp.client-ip=198.175.65.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="iJgULsDP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784902761; x=1816438761; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=10i5EvWAKrIKZG/5TYABM+/91AVrSm1aivuorzMif/c=; b=iJgULsDPW4bq13Cxqc6EcWJtAxQiMvuDeI5gGBzs2rfo5el791tCiMRK CcDAz1uW+K/kVafwDEWSLB3t7W46NKUODrVOK++m3EtgEwjYJAEzE5buw Qp2LyC16salg2a58HFH7FQNhiYks7GxDCnlAaMVLy8W6qR/qSu2O6RS49 GcbdwVl+P86cf/3BWovaW8jtY2iSckcPy8DT66wQ81Ccbu2nia1y8MsjU oTxDskqJ/DFWCfclvTHsBt7aWodWm7UqU78QmX+U/RmKwT3UibXxftL2v vnfXkiSxOxtybBesqX/q943FM/VFzPCa3VGTPzBFNQnQrf0no8Z9udx+l A==; X-CSE-ConnectionGUID: +c7xx0PNQYCimNCCpVxHjw== X-CSE-MsgGUID: YQKfjd1lStK7Rme/GRChOw== X-IronPort-AV: E=McAfee;i="6800,10657,11854"; a="96718653" X-IronPort-AV: E=Sophos;i="6.25,182,1779174000"; d="scan'208";a="96718653" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jul 2026 07:19:20 -0700 X-CSE-ConnectionGUID: EboXq4bNRHSFQ3hOcpjATQ== X-CSE-MsgGUID: eqlqtQLSRNijLAQLRB3Zyw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,182,1779174000"; d="scan'208";a="282027002" Received: from soc-cp83kr3.clients.intel.com (HELO [10.122.185.5]) ([10.122.185.5]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jul 2026 07:19:19 -0700 Message-ID: Date: Fri, 24 Jul 2026 09:19:19 -0500 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 14/15] KVM: x86/pmu: Advertise PerfMon version 5 on Intel hosts To: Jim Mattson Cc: Sean Christopherson , Paolo Bonzini , Peter Zijlstra , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Mingwei Zhang , Das Sandipan , Shukla Manali , Dapeng Mi , Falcon Thomas , Xudong Hao References: <20260707183405.15571-1-zide.chen@intel.com> <20260707183405.15571-15-zide.chen@intel.com> Content-Language: en-US From: "Chen, Zide" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 7/23/2026 10:20 PM, Jim Mattson wrote: > On Thu, Jul 23, 2026 at 4:25 PM Chen, Zide wrote: >> >> Currently KVM always injects #GP when the AnyThread bit is set. >> >> kvm_pmu_refresh(): pmu->reserved_bits = 0xffffffff00200000ull; >> >> I understand the concern, but I'm not aware of a better solution for >> PMUv3/4. Silently ignoring AnyThread would deviate from the >> architectural behavior and, more importantly, may give the guest the >> false impression that AnyThread is supported. Supporting AnyThread, on >> the other hand, has cross-VM information leakage concerns. > > Don't support versions 3 or 4; they aren't virtualizable. Hosts with > PMU versions 3 or 4 just get vPMU version 2. Yes, that sounds reasonable. PMUv3/v4 platforms (Nehalem, Westmere, Sandy Bridge, and Ivy Bridge) are quite old. In addition, the impact of exposing PMUv2 instead of PMUv3/v4 should be minimal.