From: Konstantin Weitz <[email protected]> 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. Signed-off-by: Konstantin Weitz <[email protected]> Signed-off-by: Christian Borntraeger <[email protected]> --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/diag.c | 44 ++++++++++++++++++++++++++++++++++++++ arch/s390/kvm/kvm-s390.c | 1 + 3 files changed, 46 insertions(+) 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..8991009 100644 --- a/arch/s390/kvm/diag.c +++ b/arch/s390/kvm/diag.c @@ -53,6 +53,48 @@ 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) { + struct task_struct *task = NULL; + struct pid *pid; + rcu_read_lock(); + pid = rcu_dereference(tcpu->pid); + if (pid) + task = get_pid_task(tcpu->pid, PIDTYPE_PID); + rcu_read_unlock(); + if (!task) + break; + if (task->flags & PF_VCPU) { + put_task_struct(task); + break; + } + vcpu_put(vcpu); + if (yield_to(task, 1)) { + vcpu_load(vcpu); + put_task_struct(task); + return 0; + } + vcpu_load(vcpu); + put_task_struct(task); + } + } + return 0; +} + static int __diag_ipl_functions(struct kvm_vcpu *vcpu) { unsigned int reg = vcpu->arch.sie_block->ipa & 0xf; @@ -89,6 +131,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu) return diag_release_pages(vcpu); case 0x44: return __diag_time_slice_end(vcpu); + case 0x9c: + return __diag_time_slice_end_directed(vcpu); case 0x308: return __diag_ipl_functions(vcpu); default: diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index d30c835..fd98914 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -74,6 +74,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { { "instruction_sigp_restart", VCPU_STAT(instruction_sigp_restart) }, { "diagnose_10", VCPU_STAT(diagnose_10) }, { "diagnose_44", VCPU_STAT(diagnose_44) }, + { "diagnose_9c", VCPU_STAT(diagnose_9c) }, { NULL } }; -- 1.7.9.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
