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Date:   Thu, 2 Nov 2023 11:23:34 +0530
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Reply-To: nikunj@amd.com
Subject: Re: [PATCH v5 13/14] x86/tsc: Mark Secure TSC as reliable clocksource
Content-Language: en-US
To:     Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org,
        thomas.lendacky@amd.com, x86@kernel.org, kvm@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
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        dave.hansen@linux.intel.com, dionnaglaze@google.com,
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References: <20231030063652.68675-1-nikunj@amd.com>
 <20231030063652.68675-14-nikunj@amd.com>
 <57d63309-51cd-4138-889d-43fbdf5ec790@intel.com>
From:   "Nikunj A. Dadhania" <nikunj@amd.com>
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On 10/30/2023 10:48 PM, Dave Hansen wrote:
> On 10/29/23 23:36, Nikunj A Dadhania wrote:
> ...
>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
>> index 15f97c0abc9d..b0a8546d3703 100644
>> --- a/arch/x86/kernel/tsc.c
>> +++ b/arch/x86/kernel/tsc.c
>> @@ -1241,7 +1241,7 @@ static void __init check_system_tsc_reliable(void)
>>  			tsc_clocksource_reliable = 1;
>>  	}
>>  #endif
>> -	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
>> +	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE) || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
>>  		tsc_clocksource_reliable = 1;
> 
> Why can't you just set X86_FEATURE_TSC_RELIABLE?

Last time when I tried, I had removed my kvmclock changes and I had set the X86_FEATURE_TSC_RELIABLE similar to Kirill's patch[1], this did not select the SecureTSC.

Let me try setting X86_FEATURE_TSC_RELIABLE and retaining my patch for skipping kvmclock.

Regards
Nikunj

1: https://lore.kernel.org/lkml/20230808162320.27297-1-kirill.shutemov@linux.intel.com/