Re: [PATCH RFC 1/6] KVM: s390: take care of clock-comparator sign control

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 02/07/2018 12:46 PM, David Hildenbrand wrote:
> Missed when enabling the Multiple-epoch facility. If the facility is
> installed and the control is set, a sign based comaprison has to be
> performed.
> 
> Right now we would inject wrong interrupts and ignore interrupt
> conditions. Also the sleep time is calculated in a wrong way.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>

applied. This will need some more testing but it probably deserves a CC stable.


> ---
>  arch/s390/kvm/interrupt.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 3ea9cfa31b16..a616e9b65f91 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -169,8 +169,15 @@ static int ckc_interrupts_enabled(struct kvm_vcpu *vcpu)
> 
>  static int ckc_irq_pending(struct kvm_vcpu *vcpu)
>  {
> -	if (vcpu->arch.sie_block->ckc >= kvm_s390_get_tod_clock_fast(vcpu->kvm))
> +	const u64 now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
> +	const u64 ckc = vcpu->arch.sie_block->ckc;
> +
> +	if (vcpu->arch.sie_block->gcr[0] & 0x0020000000000000ul) {
> +		if ((s64)ckc >= (s64)now)
> +			return 0;
> +	} else if (ckc >= now) {
>  		return 0;
> +	}
>  	return ckc_interrupts_enabled(vcpu);
>  }
> 
> @@ -1042,13 +1049,19 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> 
>  static u64 __calculate_sltime(struct kvm_vcpu *vcpu)
>  {
> -	u64 now, cputm, sltime = 0;
> +	const u64 now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
> +	const u64 ckc = vcpu->arch.sie_block->ckc;
> +	u64 cputm, sltime = 0;
> 
>  	if (ckc_interrupts_enabled(vcpu)) {
> -		now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
> -		sltime = tod_to_ns(vcpu->arch.sie_block->ckc - now);
> -		/* already expired or overflow? */
> -		if (!sltime || vcpu->arch.sie_block->ckc <= now)
> +		if (vcpu->arch.sie_block->gcr[0] & 0x0020000000000000ul) {
> +			if ((s64)now < (s64)ckc)
> +				sltime = tod_to_ns((s64)ckc - (s64)now);
> +		} else if (now < ckc) {
> +			sltime = tod_to_ns(ckc - now);
> +		}
> +		/* already expired */
> +		if (!sltime)
>  			return 0;
>  		if (cpu_timer_interrupts_enabled(vcpu)) {
>  			cputm = kvm_s390_get_cpu_timer(vcpu);
>