From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 76E041EF38E for ; Wed, 2 Jul 2025 05:10:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751433048; cv=none; b=t5DqpEsfj8GAIxQ+A+GIOY9nTsvJFUq0tRrudf+Kq5YDD1IpmoA6VTNJ/+QmYibzYQq0CyTPJTxHNFYQgsi78jCuZF5qmflnFS5M6YVw4WJCKpCg7wqc4LauW8MGNv5Pciu/6uyUT+GSTjpFun1mCd2+BqyfsYXHkdKFNSDUsfk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751433048; c=relaxed/simple; bh=vnDsnqkZVkFQ6WP3qoK7mtMNaceCb9TRU+GdjkvdOaQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JbnrTn3qPD2QzS5L6sNF9yvkf+0PdOb3soA239742nMIDRC7yhB5gw6HM2TAXnZ/imYGOI+toUMCGUJlfK4dbNpEARqkGBRN4MCSz9Gvg4zjRBLqpIud8LN9CKlJR9SgN479ka8s4tIU8Obtr2VsMqZYcsM3I6sHgZ8pjd8Dzg4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=W/rQNoI5; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none 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="W/rQNoI5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1751433046; x=1782969046; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=vnDsnqkZVkFQ6WP3qoK7mtMNaceCb9TRU+GdjkvdOaQ=; b=W/rQNoI5sH1kN29UnV9J6pbOBUZauLgcktrBsQccXqY126IyaEr1keia qlzmqm9oRSZi19LdBAIns+Bj5YMG62x4ygB4t8KkhCn90vh6yHXY9/fZ9 YQyGJgpdtaAyvGE1/OUtpnUjZGg4WKgMQt1n+3XDftePPwpt02naemi5h hOcCv3Bo4LHHvN3yLwuapa7oM5UCS7ug3XNVzizoYnNNGWaIhAWfHh2sR VjXXzrZ7EwgBCri0Y0jVKc3p6Dw1DrTYEMlQ6s3QhVtP0I/V1+vZFIBxB TRxaExqjUy1+3x82cgeR032ALH4CIIfN0nkTqvEloTeqwBLJPMgN4X2jR A==; X-CSE-ConnectionGUID: bZ1Y/c0tQmavv2h9l576GA== X-CSE-MsgGUID: n1TY4vjhSN+UO/yOVmhQNw== X-IronPort-AV: E=McAfee;i="6800,10657,11481"; a="52833049" X-IronPort-AV: E=Sophos;i="6.16,281,1744095600"; d="scan'208";a="52833049" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jul 2025 22:10:44 -0700 X-CSE-ConnectionGUID: yCyyxUsaTWi2NZOmBgoTAw== X-CSE-MsgGUID: T9URMdmrTSCvmP35sRIXjQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,281,1744095600"; d="scan'208";a="153432671" Received: from dapengmi-mobl1.ccr.corp.intel.com (HELO [10.124.240.80]) ([10.124.240.80]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jul 2025 22:10:40 -0700 Message-ID: Date: Wed, 2 Jul 2025 13:10:37 +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 v6 6/9] target/i386/kvm: query kvm.enable_pmu parameter To: Dongli Zhang , qemu-devel@nongnu.org, kvm@vger.kernel.org Cc: pbonzini@redhat.com, zhao1.liu@intel.com, mtosatti@redhat.com, sandipan.das@amd.com, babu.moger@amd.com, likexu@tencent.com, like.xu.linux@gmail.com, groug@kaod.org, khorenko@virtuozzo.com, alexander.ivanov@virtuozzo.com, den@virtuozzo.com, davydov-max@yandex-team.ru, xiaoyao.li@intel.com, joe.jin@oracle.com, ewanhai-oc@zhaoxin.com, ewanhai@zhaoxin.com References: <20250624074421.40429-1-dongli.zhang@oracle.com> <20250624074421.40429-7-dongli.zhang@oracle.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: <20250624074421.40429-7-dongli.zhang@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/24/2025 3:43 PM, Dongli Zhang wrote: > When PMU is enabled in QEMU, there is a chance that PMU virtualization is > completely disabled by the KVM module parameter kvm.enable_pmu=N. > > The kvm.enable_pmu parameter is introduced since Linux v5.17. > Its permission is 0444. It does not change until a reload of the KVM > module. > > Read the kvm.enable_pmu value from the module sysfs to give a chance to > provide more information about vPMU enablement. > > Signed-off-by: Dongli Zhang > Reviewed-by: Zhao Liu > --- > Changed since v2: > - Rework the code flow following Zhao's suggestion. > - Return error when: > (*kvm_enable_pmu == 'N' && X86_CPU(cpu)->enable_pmu) > Changed since v3: > - Re-split the cases into enable_pmu and !enable_pmu, following Zhao's > suggestion. > - Rework the commit messages. > - Bring back global static variable 'kvm_pmu_disabled' from v2. > Changed since v4: > - Add Reviewed-by from Zhao. > Changed since v5: > - Rebase on top of most recent QEMU. > > target/i386/kvm/kvm.c | 61 +++++++++++++++++++++++++++++++------------ > 1 file changed, 44 insertions(+), 17 deletions(-) > > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index 824148688d..d191dd1da3 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -186,6 +186,10 @@ static int has_triple_fault_event; > static bool has_msr_mcg_ext_ctl; > > static int pmu_cap; > +/* > + * Read from /sys/module/kvm/parameters/enable_pmu. > + */ > +static bool kvm_pmu_disabled; > > static struct kvm_cpuid2 *cpuid_cache; > static struct kvm_cpuid2 *hv_cpuid_cache; > @@ -2050,23 +2054,30 @@ int kvm_arch_pre_create_vcpu(CPUState *cpu, Error **errp) > if (first) { > first = false; > > - /* > - * Since Linux v5.18, KVM provides a VM-level capability to easily > - * disable PMUs; however, QEMU has been providing PMU property per > - * CPU since v1.6. In order to accommodate both, have to configure > - * the VM-level capability here. > - * > - * KVM_PMU_CAP_DISABLE doesn't change the PMU > - * behavior on Intel platform because current "pmu" property works > - * as expected. > - */ > - if ((pmu_cap & KVM_PMU_CAP_DISABLE) && !X86_CPU(cpu)->enable_pmu) { > - ret = kvm_vm_enable_cap(kvm_state, KVM_CAP_PMU_CAPABILITY, 0, > - KVM_PMU_CAP_DISABLE); > - if (ret < 0) { > - error_setg_errno(errp, -ret, > - "Failed to set KVM_PMU_CAP_DISABLE"); > - return ret; > + if (X86_CPU(cpu)->enable_pmu) { > + if (kvm_pmu_disabled) { > + warn_report("Failed to enable PMU since " > + "KVM's enable_pmu parameter is disabled"); > + } > + } else { > + /* > + * Since Linux v5.18, KVM provides a VM-level capability to easily > + * disable PMUs; however, QEMU has been providing PMU property per > + * CPU since v1.6. In order to accommodate both, have to configure > + * the VM-level capability here. > + * > + * KVM_PMU_CAP_DISABLE doesn't change the PMU > + * behavior on Intel platform because current "pmu" property works > + * as expected. > + */ > + if (pmu_cap & KVM_PMU_CAP_DISABLE) { > + ret = kvm_vm_enable_cap(kvm_state, KVM_CAP_PMU_CAPABILITY, 0, > + KVM_PMU_CAP_DISABLE); > + if (ret < 0) { > + error_setg_errno(errp, -ret, > + "Failed to set KVM_PMU_CAP_DISABLE"); > + return ret; > + } > } > } > } > @@ -3273,6 +3284,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > int ret; > struct utsname utsname; > Error *local_err = NULL; > + g_autofree char *kvm_enable_pmu; > > /* > * Initialize confidential guest (SEV/TDX) context, if required > @@ -3409,6 +3421,21 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > > pmu_cap = kvm_check_extension(s, KVM_CAP_PMU_CAPABILITY); > > + /* > + * The enable_pmu parameter is introduced since Linux v5.17, > + * give a chance to provide more information about vPMU > + * enablement. > + * > + * The kvm.enable_pmu's permission is 0444. It does not change > + * until a reload of the KVM module. > + */ > + if (g_file_get_contents("/sys/module/kvm/parameters/enable_pmu", > + &kvm_enable_pmu, NULL, NULL)) { > + if (*kvm_enable_pmu == 'N') { > + kvm_pmu_disabled = true; > + } > + } > + > return 0; > } > Reviewed-by: Dapeng Mi