linux-kernel - Re: [PATCH v2] release kvmclock page on reset

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Message-ID: <4D486CE6.4050601@web.de>
Date:	Tue, 01 Feb 2011 21:28:22 +0100
From:	Jan Kiszka <jan.kiszka@....de>
To:	Glauber Costa <glommer@...hat.com>
CC:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	aliguori@...ibm.com
Subject: Re: [PATCH v2] release kvmclock page on reset

On 2011-02-01 20:16, Glauber Costa wrote:
> When a vcpu is reset, kvmclock page keeps being writen to this days.
> This is wrong and inconsistent: a cpu reset should take it to its
> initial state.
> 
> Signed-off-by: Glauber Costa <glommer@...hat.com>
> CC: Jan Kiszka <jan.kiszka@...mens.com>
> ---
>  arch/x86/kvm/x86.c |   20 ++++++++++++--------
>  1 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index bcc0efc..c39ab4a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1453,6 +1453,14 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
>  	return 0;
>  }
>  
> +static void kvmclock_reset(struct kvm_vcpu *vcpu)
> +{
> +	if (vcpu->arch.time_page) {
> +		kvm_release_page_dirty(vcpu->arch.time_page);
> +		vcpu->arch.time_page = NULL;
> +	}
> +}
> +
>  int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>  {
>  	switch (msr) {
> @@ -1510,10 +1518,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>  		break;
>  	case MSR_KVM_SYSTEM_TIME_NEW:
>  	case MSR_KVM_SYSTEM_TIME: {
> -		if (vcpu->arch.time_page) {
> -			kvm_release_page_dirty(vcpu->arch.time_page);
> -			vcpu->arch.time_page = NULL;
> -		}
> +		kvmclock_reset(vcpu);
>  
>  		vcpu->arch.time = data;
>  		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
> @@ -5814,10 +5819,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
>  
>  void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
>  {
> -	if (vcpu->arch.time_page) {
> -		kvm_release_page_dirty(vcpu->arch.time_page);
> -		vcpu->arch.time_page = NULL;
> -	}
> +	kvmclock_reset(vcpu);
>  
>  	free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
>  	fx_free(vcpu);
> @@ -5878,6 +5880,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
>  	kvm_make_request(KVM_REQ_EVENT, vcpu);
>  	vcpu->arch.apf.msr_val = 0;
>  
> +	kvmclock_reset(vcpu);
> +
>  	kvm_clear_async_pf_completion_queue(vcpu);
>  	kvm_async_pf_hash_reset(vcpu);
>  	vcpu->arch.apf.halted = false;

Looks good.

Thanks,
Jan


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