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Date:   Wed, 24 May 2023 16:19:29 +0800
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Subject: Re: [PATCH v3 06/21] KVM:x86: Report XSS as to-be-saved if there are
 supported features
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To:     Chao Gao <chao.gao@intel.com>
CC:     <seanjc@google.com>, <pbonzini@redhat.com>, <kvm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <peterz@infradead.org>,
        <rppt@kernel.org>, <binbin.wu@linux.intel.com>,
        <rick.p.edgecombe@intel.com>, <john.allen@amd.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>
References: <20230511040857.6094-1-weijiang.yang@intel.com>
 <20230511040857.6094-7-weijiang.yang@intel.com> <ZG23e/zYAiRlfrk9@chao-email>
From:   "Yang, Weijiang" <weijiang.yang@intel.com>
In-Reply-To: <ZG23e/zYAiRlfrk9@chao-email>
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On 5/24/2023 3:06 PM, Chao Gao wrote:
> On Thu, May 11, 2023 at 12:08:42AM -0400, Yang Weijiang wrote:
>> From: Sean Christopherson <sean.j.christopherson@intel.com>
>>
>> Add MSR_IA32_XSS to the list of MSRs reported to userspace if
>> supported_xss is non-zero, i.e. KVM supports at least one XSS based
>> feature.
> The changelog doesn't match what the patch does.
>
> Do you need to check if supported_xss is non-zero in kvm_probe_msr_to_save(),
> e.g.,
>          case MSR_IA32_XSS:
>                  if (!kvm_caps.supported_xss)
>                          return;
>                  break;

I looked back the history of this patch, there's similar check 
originally, however it's lost

during following rebases. I'll add it back. Thanks for pointing it out!

>> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> ---
>> arch/x86/kvm/x86.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index e7f78fe79b32..33a780fe820b 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -1454,6 +1454,7 @@ static const u32 msrs_to_save_base[] = {
>> 	MSR_IA32_UMWAIT_CONTROL,
>>
>> 	MSR_IA32_XFD, MSR_IA32_XFD_ERR,
>> +	MSR_IA32_XSS,
>> };
>>
>> static const u32 msrs_to_save_pmu[] = {
>> -- 
>> 2.27.0
>>