From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (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 571DF250BF2; Tue, 18 Aug 2026 20:00:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787083240; cv=none; b=jMo1yudSxN04NcJkR3CsV2Zdr2FbWBOUuMkEy7wBZYGdUwpJoieRLbvg2BdoKy3RvAqPPVUvFFDiIKYunaG7itAaTGI7Vpz8w4ETiB73UD4GgUS9f+ZIBMuLmNM+A+UFoNuFEps6UyYXhMKlArMLDQstbtE7QcgayDF9kBL8QyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787083240; c=relaxed/simple; bh=7zAeiKb4ZItCbyXLv1015NYGnA0+lBqnTy+Fa7pNleA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GdHI8DNUdkpQekxkLnuvj1BHYOhEUjrKLZlIwTCObJBbWrg3EFrWUTWMryCeMq+VBbrNSoLh8g/+G4nPSXVuAW6IQvJDOqtP4YJrpIa3KCYERcs2nrh9zInh/fOcLd1UE/nVDn5EJtx/1+c1jiYrO40+IstXu3gSC4eTd6HcGAE= 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=bpKApbI6; arc=none smtp.client-ip=198.175.65.14 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="bpKApbI6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1787083237; x=1818619237; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=7zAeiKb4ZItCbyXLv1015NYGnA0+lBqnTy+Fa7pNleA=; b=bpKApbI6Ni9Ai1nvt3t1d9jm1mVKndIRDRXUTwP/dhhe7kAIB1HXe0WP uTGOiPU4/aTf2zh/zpo82Ku0TfpWDwUrGP4AZ6KsiN2/s4YWMI3RYy//X fZ1/eME4IxFrIwrhV1GS+cg25ereCb+ngg2zxLm7tRCGOf0LYZ0ufx/El ZDFNHP8PC+sPG6ItF6zIYfEOKY26cBz5mWvVM/2jweSDQ7CUw7jeTkZ5O qNnDaJNZCbNpWYQ6HrtFAK9iAHTck2ElLAKGuoe6b1xDvHsejinj3np/F my+4zEwJAOrwEdGmQ4R9dBVv/tbVJZHlAsIGA9CnsN+cVNYmYWCnOxH+5 Q==; X-CSE-ConnectionGUID: OCZwwX+DSfePrvjhUlfalw== X-CSE-MsgGUID: N3yX2wDaS6e9FxINnOs7Dg== X-IronPort-AV: E=McAfee;i="6800,10657,11879"; a="91459976" X-IronPort-AV: E=Sophos;i="6.25,230,1779174000"; d="scan'208";a="91459976" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 12:59:59 -0700 X-CSE-ConnectionGUID: brBZbxT6Rn6ivUtx+eDkMw== X-CSE-MsgGUID: ONIhI39URw6d4aNvo0WvNA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,230,1779174000"; d="scan'208";a="270520154" Received: from soc-cp83kr3.clients.intel.com (HELO [10.122.185.5]) ([10.122.185.5]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 12:59:57 -0700 Message-ID: Date: Tue, 18 Aug 2026 14:59:56 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 7/8] KVM: x86/pmu: Emulate RDPMC on performance metrics To: Andi Kleen Cc: Sean Christopherson , Paolo Bonzini , kvm@vger.kernel.org, Jim Mattson , linux-kernel@vger.kernel.org, Mingwei Zhang , Das Sandipan , Shukla Manali , Dapeng Mi , Xudong Hao References: <20260817183143.226156-1-zide.chen@intel.com> <20260817183143.226156-8-zide.chen@intel.com> Content-Language: en-US From: "Chen, Zide" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/18/2026 2:24 PM, Andi Kleen wrote: > On Tue, Aug 18, 2026 at 01:30:32PM -0500, Chen, Zide wrote: >> >> >> On 8/18/2026 12:41 PM, Andi Kleen wrote: >>> On Mon, Aug 17, 2026 at 11:31:41AM -0700, Zide Chen wrote: >>>> If the host has the PERF_METRICS capability but it's not present on >>>> the guest, RDPMC interception must be enabled and KVM should inject >>>> an #GP when the guest attempts a PERF_METRICS RDPMC. >>>> >>>> If the guest has PERF_METRICS but RDPMC interception is enabled for >>>> other reasons, KVM needs to emulate RDPMC with type 0x2000. >>>> >>>> For simplicity, Metrics Clear Mode is not supported. >>> >>> But is the bit cleared in PERF_CAPABILITIES? And would >>> the enable bit fault? >> >> Currently KVM doesn't advertise >> IA32_PERF_CAPABILITIES.RDPMC_METRICS_CLEAR[19]. > > Thanks. > > How about the fault for the enable bit? Yes, KVM always injects a #GP if the guest writes IA32_FIXED_CTR_CTRL.METRICS_CLEAR_EN[bit 14]. > >>> It would be better to just support it, metrics clear is actually useful. >> >> Sure, I'll add it. > > I guess it could be a follow-on patch, no need to hold up this one. OK.