From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: [PATCH 1/2] kvm-s390: Implement the directed yield (diag 9c) hypervisor call for KVM Date: Wed, 25 Apr 2012 15:30:38 +0200 Message-ID: <1335360639-6004-2-git-send-email-borntraeger@de.ibm.com> References: <4F96D34E.4010405@redhat.com> <1335360639-6004-1-git-send-email-borntraeger@de.ibm.com> Cc: Carsten Otte , Alexander Graf , Jens Freimann , Cornelia Huck , Heiko Carstens , Martin Schwidefsky , Heinz Graalfs , KVM , Konstantin Weitz , Christian Borntraeger To: Avi Kivity , Marcelo Tossati Return-path: Received: from e06smtp18.uk.ibm.com ([195.75.94.114]:44217 "EHLO e06smtp18.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751376Ab2DYNaq (ORCPT ); Wed, 25 Apr 2012 09:30:46 -0400 Received: from /spool/local by e06smtp18.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 25 Apr 2012 14:30:45 +0100 Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by d06nrmr1307.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q3PDUg9M2724068 for ; Wed, 25 Apr 2012 14:30:42 +0100 Received: from d06av02.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q3PDUfpA014557 for ; Wed, 25 Apr 2012 07:30:42 -0600 In-Reply-To: <1335360639-6004-1-git-send-email-borntraeger@de.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: From: Konstantin Weitz 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 Signed-off-by: Christian Borntraeger --- 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) { + kvm_vcpu_yield_to(tcpu); + break; + } + + return 0; +} + static int __diag_ipl_functions(struct kvm_vcpu *vcpu) { unsigned int reg = vcpu->arch.sie_block->ipa & 0xf; @@ -89,6 +112,8 @@ 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 044ca7e..0054cb0 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 } }; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 186ffab..2322b21 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -461,6 +461,7 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot, void kvm_vcpu_block(struct kvm_vcpu *vcpu); void kvm_vcpu_kick(struct kvm_vcpu *vcpu); +bool kvm_vcpu_yield_to(struct kvm_vcpu *target); void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu); void kvm_resched(struct kvm_vcpu *vcpu); void kvm_load_guest_fpu(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9eb7936..99a38a4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1543,6 +1543,31 @@ void kvm_resched(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_resched); +bool kvm_vcpu_yield_to(struct kvm_vcpu *target) +{ + struct pid *pid; + struct task_struct *task = NULL; + + rcu_read_lock(); + pid = rcu_dereference(target->pid); + if (pid) + task = get_pid_task(target->pid, PIDTYPE_PID); + rcu_read_unlock(); + if (!task) + return false; + if (task->flags & PF_VCPU) { + put_task_struct(task); + return false; + } + if (yield_to(task, 1)) { + put_task_struct(task); + return true; + } + put_task_struct(task); + return false; +} +EXPORT_SYMBOL_GPL(kvm_vcpu_yield_to); + void kvm_vcpu_on_spin(struct kvm_vcpu *me) { struct kvm *kvm = me->kvm; @@ -1561,8 +1586,6 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) */ for (pass = 0; pass < 2 && !yielded; pass++) { kvm_for_each_vcpu(i, vcpu, kvm) { - struct task_struct *task = NULL; - struct pid *pid; if (!pass && i < last_boosted_vcpu) { i = last_boosted_vcpu; continue; @@ -1572,24 +1595,11 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) continue; if (waitqueue_active(&vcpu->wq)) continue; - rcu_read_lock(); - pid = rcu_dereference(vcpu->pid); - if (pid) - task = get_pid_task(vcpu->pid, PIDTYPE_PID); - rcu_read_unlock(); - if (!task) - continue; - if (task->flags & PF_VCPU) { - put_task_struct(task); - continue; - } - if (yield_to(task, 1)) { - put_task_struct(task); + if (kvm_vcpu_yield_to(vcpu)) { kvm->last_boosted_vcpu = i; yielded = 1; break; } - put_task_struct(task); } } } -- 1.7.9.6