Re: KVM: x86: fix pvclock guest stopped flag reporting

[Avi Kivity <avi@redhat.com>]

On 08/02/2012 06:33 PM, Marcelo Tosatti wrote:
> 
> kvm_guest_time_update unconditionally clears hv_clock.flags field, 
> so the notification never reaches the guest.
> 
> Fix it by allowing PVCLOCK_GUEST_STOPPED to passthrough.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3a53bcc..e8ce10f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1217,7 +1217,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
>  	vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
>  	vcpu->last_kernel_ns = kernel_ns;
>  	vcpu->last_guest_tsc = tsc_timestamp;
> -	vcpu->hv_clock.flags = 0;
> +	/* only support PVCLOCK_GUEST_STOPPED flag ATM */
> +	if (vcpu->hv_clock.flags != PVCLOCK_GUEST_STOPPED)
> +		vcpu->hv_clock.flags = 0;
>  

Seems a little risky.  Should we store the flag in a separate bool and
mix it in instead of RMWing it?


-- 
error compiling committee.c: too many arguments to function