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From: Like Xu <like.xu.linux@gmail.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 05/12] KVM: x86/pmu: Error when user sets the GLOBAL_STATUS reserved bits
Date: Fri, 7 Apr 2023 13:08:59 +0800	[thread overview]
Message-ID: <37a18b89-c0c3-4c88-7f07-072573ac0c92@gmail.com> (raw)
In-Reply-To: <ZC9Zqn/+J5vaXKfo@google.com>

On 7/4/2023 7:45 am, Sean Christopherson wrote:
> On Tue, Feb 14, 2023, Like Xu wrote:
>> From: Like Xu <likexu@tencent.com>
>>
>> If the user space sets reserved bits when restoring the MSR_CORE_
>> PERF_GLOBAL_STATUS register, these bits will be accidentally returned
>> when the guest runs a read access to this register, and cannot be cleared
>> up inside the guest, which makes the guest's PMI handler very confused.
> 
> The changelog needs to state what the patch actually does.
> 
>> Signed-off-by: Like Xu <likexu@tencent.com>
>> ---
>>   arch/x86/kvm/vmx/pmu_intel.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
>> index 904f832fc55d..aaea25d2cae8 100644
>> --- a/arch/x86/kvm/vmx/pmu_intel.c
>> +++ b/arch/x86/kvm/vmx/pmu_intel.c
>> @@ -397,7 +397,7 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>   			reprogram_fixed_counters(pmu, data);
>>   		break;
>>   	case MSR_CORE_PERF_GLOBAL_STATUS:
>> -		if (!msr_info->host_initiated)
>> +		if (!msr_info->host_initiated || (data & pmu->global_ovf_ctrl_mask))
> 
> This is wrong.  Bits 60:58 are reserved in IA32_PERF_GLOBAL_OVF_CTRL, but are
> ASCI, CTR_FREEZE, and LBR_FREEZE respectively in MSR_CORE_PERF_GLOBAL_STATUS.

CTR_FREEZE and LBR_FREEZE are only required for the guest CPUID.0AH: EAX[7:0]>3.
PMU support (ASCI bit) for guest SGX isn't supported either.

So for now, reusing pmu->global_ovf_ctrl_mask here is effective enough.

> 
>>   			return 1; /* RO MSR */
>>   
>>   		pmu->global_status = data;
>> -- 
>> 2.39.1
>>

  reply	other threads:[~2023-04-07  5:09 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-14  5:07 [PATCH v4 00/12] KVM: x86: Add AMD Guest PerfMonV2 PMU support Like Xu
2023-02-14  5:07 ` [PATCH v4 01/12] KVM: x86/pmu: Rename pmc_is_enabled() to pmc_is_globally_enabled() Like Xu
2023-02-14  5:07 ` [PATCH v4 02/12] KVM: VMX: Refactor intel_pmu_set_msr() to align with other set_msr() helpers Like Xu
2023-02-16 21:13   ` Sean Christopherson
2023-02-21  8:44     ` Like Xu
2023-03-23  7:43       ` Like Xu
2023-03-23 14:28         ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 03/12] KVM: x86/pmu: Rewrite reprogram_counters() to improve performance Like Xu
2023-02-14  5:07 ` [PATCH v4 04/12] KVM: x86/pmu: Expose reprogram_counters() in pmu.h Like Xu
2023-02-14  5:07 ` [PATCH v4 05/12] KVM: x86/pmu: Error when user sets the GLOBAL_STATUS reserved bits Like Xu
2023-04-06 23:45   ` Sean Christopherson
2023-04-07  5:08     ` Like Xu [this message]
2023-04-07 15:43       ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 06/12] KVM: x86/pmu: Make part of the Intel v2 PMU MSRs handling x86 generic Like Xu
2023-04-06 23:57   ` Sean Christopherson
2023-04-07  1:39   ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 07/12] KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu Like Xu
2023-04-06 23:59   ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 08/12] KVM: x86/pmu: Disable vPMU if the minimum num of counters isn't met Like Xu
2023-04-07  0:06   ` Sean Christopherson
2023-04-07  0:23     ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 09/12] KVM: x86/pmu: Forget PERFCTR_CORE if the min " Like Xu
2023-04-07  0:32   ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 10/12] KVM: x86/cpuid: Add X86_FEATURE_PERFMON_V2 as a scattered flag Like Xu
2023-04-07  0:41   ` Sean Christopherson
2023-02-14  5:07 ` [PATCH v4 11/12] KVM: x86/svm/pmu: Add AMD PerfMonV2 support Like Xu
2023-04-07  1:35   ` Sean Christopherson
2023-04-07  7:08     ` Like Xu
2023-04-07 14:44       ` Sean Christopherson
2023-04-10 11:34         ` Like Xu
2023-02-14  5:07 ` [PATCH v4 12/12] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022 Like Xu
2023-04-07  1:50   ` Sean Christopherson
2023-04-07  7:19     ` Like Xu
2023-04-07  2:02 ` [PATCH v4 00/12] KVM: x86: Add AMD Guest PerfMonV2 PMU support Sean Christopherson
2023-04-07  7:28   ` Like Xu

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