On 25.04.2012, at 15:30, Christian Borntraeger wrote:
> From: Konstantin Weitz <WEITZKON@xxxxxxxxxx>
>
> This patch implements the directed yield hypercall found on other
> System z hypervisors. It delegates execution time to the virtual cpu
> specified in the instruction's parameter.
>
> Useful to avoid long spinlock waits in the guest.
>
> Christian Borntraeger: moved common code in virt/kvm/
>
> Signed-off-by: Konstantin Weitz <WEITZKON@xxxxxxxxxx>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/s390/include/asm/kvm_host.h | 1 +
> arch/s390/kvm/diag.c | 25 +++++++++++++++++++++++
> arch/s390/kvm/kvm-s390.c | 1 +
> include/linux/kvm_host.h | 1 +
> virt/kvm/kvm_main.c | 42 +++++++++++++++++++++++---------------
> 5 files changed, 54 insertions(+), 16 deletions(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 7343872..dd17537 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -148,6 +148,7 @@ struct kvm_vcpu_stat {
> u32 instruction_sigp_restart;
> u32 diagnose_10;
> u32 diagnose_44;
> + u32 diagnose_9c;
> };
>
> struct kvm_s390_io_info {
> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> index a353f0e..2d2ae32 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -53,6 +53,29 @@ static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
> return 0;
> }
>
> +static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_vcpu *tcpu;
> + int tid;
> + int i;
> +
> + tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
> + vcpu->stat.diagnose_9c++;
> + VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d", tid);
> +
> + if (tid == vcpu->vcpu_id)
> + return 0;
> +
> + kvm_for_each_vcpu(i, tcpu, kvm)
> + if (tcpu->vcpu_id == tid) {
Wouldn't
kvm_get_vcpu(kvm, tid)
be what you want here?
Alex
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