From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: [PATCH 2/2] KVM: x86: fix maintaining of kvm_clock stability on
 guest CPU hotplug
Date: Thu, 6 Apr 2017 19:25:13 +0200
Message-ID: <20170406172512.GA23559@potion>
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Cc: pbonzini@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org,
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To: Denis Plotnikov <dplotnikov@virtuozzo.com>
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2017-04-06 19:11+0200, Radim Krčmář:
> 2017-04-06 11:08+0300, Denis Plotnikov:
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> @@ -1455,15 +1455,23 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
>>  	elapsed = ns - kvm->arch.last_tsc_nsec;
>>  
>>  	if (vcpu->arch.virtual_tsc_khz) {
>> -		u64 tsc_exp = kvm->arch.last_tsc_write +
>> -					nsec_to_cycles(vcpu, elapsed);
>> -		u64 tsc_hz = vcpu->arch.virtual_tsc_khz * 1000LL;
>> -		/*
>> -		 * Special case: TSC write with a small delta (1 second) of virtual
>> -		 * cycle time against real time is interpreted as an attempt to
>> -		 * synchronize the CPU.
>> -		 */
>> -		synchronizing = data < tsc_exp + tsc_hz && data > tsc_exp - tsc_hz;
>> +		if ((data == 0) && msr->host_initiated) {

And while I'm nitpicking ... the code would also be nicer without the
parentheses around data.