Re: [PATCH v2] kvm-s390: Provide guest TOD Clock Get/Set Controls

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/11/2014 15:55, Jason J. Herne wrote:
> From: "Jason J. Herne" <jjherne@linux.vnet.ibm.com>
> 
> Provide KVM_REG_S390_TOD and KVM_REG_S390_TOD_HIGH registers on s390 for
> managing guest Time Of Day clock value.
> 
> KVM_REG_S390_TOD_HIGH is presently always set to 0. In the future it will
> contain a high order expansion of the tod clock value after it overflows
> the 64-bits of KVM_REG_S390_TOD.
> 
> Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
> ---
>  arch/s390/include/uapi/asm/kvm.h |  2 ++
>  arch/s390/kvm/kvm-s390.c         | 63 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 65 insertions(+)
> 
> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
> index 48eda3a..5578832 100644
> --- a/arch/s390/include/uapi/asm/kvm.h
> +++ b/arch/s390/include/uapi/asm/kvm.h
> @@ -138,4 +138,6 @@ struct kvm_sync_regs {
>  #define KVM_REG_S390_PFSELECT	(KVM_REG_S390 | KVM_REG_SIZE_U64 | 0x7)
>  #define KVM_REG_S390_PP		(KVM_REG_S390 | KVM_REG_SIZE_U64 | 0x8)
>  #define KVM_REG_S390_GBEA	(KVM_REG_S390 | KVM_REG_SIZE_U64 | 0x9)
> +#define KVM_REG_S390_TOD	(KVM_REG_S390 | KVM_REG_SIZE_U64 | 0xA)
> +#define KVM_REG_S390_TOD_HIGH	(KVM_REG_S390 | KVM_REG_SIZE_U8 | 0xB)
>  #endif
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 55aade4..17e3d61 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -31,6 +31,7 @@
>  #include <asm/switch_to.h>
>  #include <asm/facility.h>
>  #include <asm/sclp.h>
> +#include<asm/timex.h>
>  #include "kvm-s390.h"
>  #include "gaccess.h"
>  
> @@ -788,10 +789,48 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
>  	return 0;
>  }
>  
> +static int kvm_s390_get_guest_tod(struct kvm_vcpu *vcpu, u64 *guest_tod)
> +{
> +	u64 host_tod;
> +	int r;
> +
> +	r = store_tod_clock(&host_tod);
> +	if (r)
> +		return r;
> +
> +	*guest_tod = host_tod + vcpu->arch.sie_block->epoch;
> +	return 0;
> +}
> +
> +/*
> +Set the guest's effective TOD clock to the given value. The guest's
> +TOD clock is determined by the following formula: gtod = host_tod + epoch.
> +NOTE: Even though the epoch value is associated with a vcpu, there is only
> +one TOD clock and epoch value per guest.  All vcpu's epoch values must be kept
> +synchronized.
> +*/
> +static int kvm_s390_set_guest_tod(struct kvm_vcpu *vcpu, u64 guest_tod)
> +{
> +	struct kvm_vcpu *cur_vcpu;
> +	unsigned int vcpu_idx;
> +	u64 host_tod;
> +	int r;
> +
> +	r = store_tod_clock(&host_tod);
> +	if (r)
> +		return r;
> +
> +	kvm_for_each_vcpu(vcpu_idx, cur_vcpu, vcpu->kvm) {
> +		cur_vcpu->arch.sie_block->epoch = guest_tod - host_tod;
> +	}
> +	return 0;
> +}
> +
>  static int kvm_arch_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
>  					   struct kvm_one_reg *reg)
>  {
>  	int r = -EINVAL;
> +	u64 gtod;
>  
>  	switch (reg->id) {
>  	case KVM_REG_S390_TODPR:
> @@ -830,6 +869,15 @@ static int kvm_arch_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
>  		r = put_user(vcpu->arch.sie_block->gbea,
>  			     (u64 __user *)reg->addr);
>  		break;
> +	case KVM_REG_S390_TOD:
> +		r = kvm_s390_get_guest_tod(vcpu, &gtod);
> +		if (r)
> +			break;
> +		r = put_user(gtod, (u64 __user *)reg->addr);
> +		break;
> +	case KVM_REG_S390_TOD_HIGH:
> +		r = put_user(0, (u8 __user *)reg->addr);
> +		break;
>  	default:
>  		break;
>  	}
> @@ -841,6 +889,8 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
>  					   struct kvm_one_reg *reg)
>  {
>  	int r = -EINVAL;
> +	u64 gtod;
> +	u8 gtod_high;
>  
>  	switch (reg->id) {
>  	case KVM_REG_S390_TODPR:
> @@ -879,6 +929,19 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
>  		r = get_user(vcpu->arch.sie_block->gbea,
>  			     (u64 __user *)reg->addr);
>  		break;
> +	case KVM_REG_S390_TOD:
> +		r = get_user(gtod, (u64 __user *)reg->addr);
> +		if (r)
> +			break;
> +		r = kvm_s390_set_guest_tod(vcpu, gtod);
> +		break;
> +	case KVM_REG_S390_TOD_HIGH:
> +		r = get_user(gtod_high, (u8 __user *)reg->addr);
> +		if (r)
> +			break;
> +		if (gtod_high != 0)
> +			r = -EINVAL;
> +		break;
>  	default:
>  		break;
>  	}
> 

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Thanks!

Paolo