From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (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 B01EE32E757 for ; Tue, 10 Feb 2026 07:07:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770707274; cv=none; b=JOVaJ7pX5PVDADewW+rp1QwXvJ2nSar2gG5fQjIZZ+KgKC/EKGPKq8zU8iBKrwH8skDaB5dUCW0d6itu2iXAwlr8h6/30i95kxPCzk6kpj8zINaGfUL8yFxt0YtqGyfdH+wT5KzJl+BVfIHpp2dMxsjsqirtjRqfzhesMRvQQdY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770707274; c=relaxed/simple; bh=VCHm+1U7yx0luMTFJ4dTIegtYJP0FVqEZIZriluU/LE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iHGS5X8cjpU4DSd9Emzj0S9B1Xud/Z+pliBW5kNJ/7WAEe81FgIhVgr9DU6BZKLEHHxTv0bBqTDzy6fbtqY1KDuJwpc2zOHhRnAKQKb1vXFZQVfiVejMO4nX7JVZrTqPL09hvgn4ZphnVPzrsbBeEFTJQ49TZX8YE0A1O7xx1yM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PRFYLgts; arc=none smtp.client-ip=192.198.163.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PRFYLgts" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770707273; x=1802243273; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=VCHm+1U7yx0luMTFJ4dTIegtYJP0FVqEZIZriluU/LE=; b=PRFYLgts62FYj9erbYwhozs1pjfGFBbgZeQYFqB1IVIbwnIOSNwzR1r2 nyHfUlmf+B1q/Y6nOm28jqA9K07WynZC8DiVaEnV1yuOB3oFH8La7u93E BAkVP8sKtUzXFW88s582XRDRGPVGWWyqPrBVa1Nz1uNK2tqchts6yckqn +fMxOuU7L2Fv/TYxGyaVQdZmJM8NnOa06hcXk4uV2tTgCvPEmYEURuuuk 4J0MyxHCSa3CJUb6izTbKh/sVjhjRrOdKRAoBYv8utVh9VzQmV36Oo22z YOUYbSZ72bg4eCTLFXA8QMMmWqfE5Ds6g0DbQoIM9Q+8Y1uuQZLUlapHO w==; X-CSE-ConnectionGUID: eo1VlGxzSMm0d3g6Ib+mzg== X-CSE-MsgGUID: x8yQUrB4Q42vyDFCnYWB6w== X-IronPort-AV: E=McAfee;i="6800,10657,11696"; a="71039005" X-IronPort-AV: E=Sophos;i="6.21,283,1763452800"; d="scan'208";a="71039005" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2026 23:07:52 -0800 X-CSE-ConnectionGUID: GRhIKsADTVSQ1t+LQYmsqA== X-CSE-MsgGUID: 9spyRXT5SyWOs1i1oC+1Uw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,283,1763452800"; d="scan'208";a="211038275" Received: from qianm-mobl2.ccr.corp.intel.com (HELO [10.238.1.184]) ([10.238.1.184]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2026 23:07:49 -0800 Message-ID: Date: Tue, 10 Feb 2026 15:07:47 +0800 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 V2 08/11] target/i386: Clean up LBR format handling To: Zide Chen , qemu-devel@nongnu.org, kvm@vger.kernel.org, Paolo Bonzini , Zhao Liu , Peter Xu , Fabiano Rosas Cc: Xiaoyao Li , Dongli Zhang References: <20260128231003.268981-1-zide.chen@intel.com> <20260128231003.268981-9-zide.chen@intel.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: <20260128231003.268981-9-zide.chen@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/29/2026 7:09 AM, Zide Chen wrote: > Since the lbr-fmt property is masked with PERF_CAP_LBR_FMT in > DEFINE_PROP_UINT64_CHECKMASK(), there is no need to explicitly validate > user-requested lbr-fmt values. > > The PMU feature is only supported when running under KVM, so initialize > cpu->lbr_fmt in kvm_cpu_instance_init(). Use -1 as the default lbr-fmt, > rather than initializing it with ~PERF_CAP_LBR_FMT, which is misleading > as it suggests a semantic relationship that does not exist. > > Rename requested_lbr_fmt to a more generic guest_fmt. When lbr-fmt is > not specified and cpu->migratable is false, the guest lbr_fmt value is > not user-requested. > > Signed-off-by: Zide Chen > --- > V2: > - New patch. > > target/i386/cpu.c | 18 ++++++------------ > target/i386/kvm/kvm-cpu.c | 2 ++ > 2 files changed, 8 insertions(+), 12 deletions(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index f2c83b4f259c..09180c718d58 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -9788,7 +9788,7 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp) > X86CPUClass *xcc = X86_CPU_GET_CLASS(dev); > CPUX86State *env = &cpu->env; > Error *local_err = NULL; > - unsigned requested_lbr_fmt; > + unsigned guest_fmt; > > if (!kvm_enabled()) > cpu->enable_pmu = false; > @@ -9828,11 +9828,7 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp) > * Override env->features[FEAT_PERF_CAPABILITIES].LBR_FMT > * with user-provided setting. > */ > - if (cpu->lbr_fmt != ~PERF_CAP_LBR_FMT) { > - if ((cpu->lbr_fmt & PERF_CAP_LBR_FMT) != cpu->lbr_fmt) { > - error_setg(errp, "invalid lbr-fmt"); > - return; > - } > + if (cpu->lbr_fmt != -1) { > env->features[FEAT_PERF_CAPABILITIES] &= ~PERF_CAP_LBR_FMT; > env->features[FEAT_PERF_CAPABILITIES] |= cpu->lbr_fmt; > } > @@ -9841,9 +9837,8 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp) > * vPMU LBR is supported when 1) KVM is enabled 2) Option pmu=on and > * 3)vPMU LBR format matches that of host setting. > */ > - requested_lbr_fmt = > - env->features[FEAT_PERF_CAPABILITIES] & PERF_CAP_LBR_FMT; > - if (requested_lbr_fmt && kvm_enabled()) { > + guest_fmt = env->features[FEAT_PERF_CAPABILITIES] & PERF_CAP_LBR_FMT; > + if (guest_fmt) { > uint64_t host_perf_cap = > x86_cpu_get_supported_feature_word(NULL, FEAT_PERF_CAPABILITIES); > unsigned host_lbr_fmt = host_perf_cap & PERF_CAP_LBR_FMT; > @@ -9852,10 +9847,10 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp) > error_setg(errp, "vPMU: LBR is unsupported without pmu=on"); > return; > } > - if (requested_lbr_fmt != host_lbr_fmt) { > + if (guest_fmt != host_lbr_fmt) { > error_setg(errp, "vPMU: the lbr-fmt value (0x%x) does not match " > "the host value (0x%x).", > - requested_lbr_fmt, host_lbr_fmt); > + guest_fmt, host_lbr_fmt); > return; > } > } > @@ -10279,7 +10274,6 @@ static void x86_cpu_initfn(Object *obj) > object_property_add_alias(obj, "sse4_2", obj, "sse4.2"); > > object_property_add_alias(obj, "hv-apicv", obj, "hv-avic"); > - cpu->lbr_fmt = ~PERF_CAP_LBR_FMT; > object_property_add_alias(obj, "lbr_fmt", obj, "lbr-fmt"); > > if (xcc->model) { > diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c > index 33a8c26bc27c..b4500ab69f82 100644 > --- a/target/i386/kvm/kvm-cpu.c > +++ b/target/i386/kvm/kvm-cpu.c > @@ -231,6 +231,8 @@ static void kvm_cpu_instance_init(CPUState *cs) > kvm_cpu_max_instance_init(cpu); > } > > + cpu->lbr_fmt = -1; > + > kvm_cpu_xsave_init(); > } > Reviewed-by: Dapeng Mi