From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.120]) (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 4FE9C29D07; Fri, 12 Jan 2024 03:50:34 +0000 (UTC) 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="S7AAR4UK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1705031434; x=1736567434; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=32XZ4fGvgZQ7I9ngj0l5boYFVTWWUsztHQpTOBJ0QK8=; b=S7AAR4UKsmFUwSVQbLuvyfc4xBRa2bNLFPXLw1Fbl6MLf1BxEHZMzFSN XxJt1wNF9l/wbIUAOjlO+Zb1jSB5odKPEzLlh78AgdSAY1Q+2QwmkizQ3 icycmvyIlqx+lUpyP5htyp0peYmwE3GyRTHqMcUZDWJXNwu17Q2pRbrXM VLh1iK/g6tcnx2zk89gviLD9/NFv6pv7C4FmMFl4g1rphg96jbBZNQSuq HPs98rz/IL0e2zn53TgffJQ82hzUOTbMdhd9/3mgMzT7OFygiVPWqoflB iw2mXpubrYBbTPfOvwIl96SM5nsx7z5yrkrUS7+DUnRrhBAourfrzrPjt g==; X-IronPort-AV: E=McAfee;i="6600,9927,10950"; a="397952993" X-IronPort-AV: E=Sophos;i="6.04,188,1695711600"; d="scan'208";a="397952993" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2024 19:50:32 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.04,188,1695711600"; d="scan'208";a="24579052" Received: from dapengmi-mobl1.ccr.corp.intel.com (HELO [10.93.5.98]) ([10.93.5.98]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2024 19:50:31 -0800 Message-ID: <35f1573e-2800-4cf1-a9f1-b3fa05d7a097@linux.intel.com> Date: Fri, 12 Jan 2024 11:50:28 +0800 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 v10 11/29] KVM: x86/pmu: Explicitly check for RDPMC of unsupported Intel PMC types Content-Language: en-US To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Kan Liang , Jim Mattson , Jinrong Liang , Aaron Lewis , Like Xu References: <20240109230250.424295-1-seanjc@google.com> <20240109230250.424295-12-seanjc@google.com> From: "Mi, Dapeng" In-Reply-To: <20240109230250.424295-12-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/10/2024 7:02 AM, Sean Christopherson wrote: > Explicitly check for attempts to read unsupported PMC types instead of > letting the bounds check fail. Functionally, letting the check fail is > ok, but it's unnecessarily subtle and does a poor job of documenting the > architectural behavior that KVM is emulating. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/vmx/pmu_intel.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > index c37dd3aa056b..b41bdb0a0995 100644 > --- a/arch/x86/kvm/vmx/pmu_intel.c > +++ b/arch/x86/kvm/vmx/pmu_intel.c > @@ -26,6 +26,7 @@ > * further confuse things, non-architectural PMUs use bit 31 as a flag for > * "fast" reads, whereas the "type" is an explicit value. > */ > +#define INTEL_RDPMC_GP 0 > #define INTEL_RDPMC_FIXED INTEL_PMC_FIXED_RDPMC_BASE > > #define INTEL_RDPMC_TYPE_MASK GENMASK(31, 16) > @@ -89,21 +90,29 @@ static struct kvm_pmc *intel_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu, > return NULL; > > /* > - * Fixed PMCs are supported on all architectural PMUs. Note, KVM only > - * emulates fixed PMCs for PMU v2+, but the flag itself is still valid, > - * i.e. let RDPMC fail due to accessing a non-existent counter. > + * General Purpose (GP) PMCs are supported on all PMUs, and fixed PMCs > + * are supported on all architectural PMUs, i.e. on all virtual PMUs > + * supported by KVM. Note, KVM only emulates fixed PMCs for PMU v2+, > + * but the type itself is still valid, i.e. let RDPMC fail due to > + * accessing a non-existent counter. Reject attempts to read all other > + * types, which are unknown/unsupported. > */ > - idx &= ~INTEL_RDPMC_FIXED; > - if (type == INTEL_RDPMC_FIXED) { > + switch (type) { > + case INTEL_RDPMC_FIXED: > counters = pmu->fixed_counters; > num_counters = pmu->nr_arch_fixed_counters; > bitmask = pmu->counter_bitmask[KVM_PMC_FIXED]; > - } else { > + break; > + case INTEL_RDPMC_GP: > counters = pmu->gp_counters; > num_counters = pmu->nr_arch_gp_counters; > bitmask = pmu->counter_bitmask[KVM_PMC_GP]; > + break; > + default: > + return NULL; > } > > + idx &= INTEL_RDPMC_INDEX_MASK; > if (idx >= num_counters) > return NULL; > Reviewed-by: Dapeng Mi