From patchwork Fri Sep 21 05:38:25 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 185583 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 068B92C0088 for ; Fri, 21 Sep 2012 15:40:15 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755242Ab2IUFkN (ORCPT ); Fri, 21 Sep 2012 01:40:13 -0400 Received: from ozlabs.org ([203.10.76.45]:33357 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754595Ab2IUFjk (ORCPT ); Fri, 21 Sep 2012 01:39:40 -0400 Received: by ozlabs.org (Postfix, from userid 1003) id 746022C0091; Fri, 21 Sep 2012 15:39:38 +1000 (EST) Date: Fri, 21 Sep 2012 15:38:25 +1000 From: Paul Mackerras To: Alexander Graf Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org Subject: [PATCH 08/10] KVM: PPC: Book3S HV: Run virtual core whenever any vcpus in it can run Message-ID: <20120921053825.GI15685@drongo> References: <20120921051606.GA15685@drongo> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20120921051606.GA15685@drongo> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Currently the Book3S HV code implements a policy on multi-threaded processors (i.e. POWER7) that requires all of the active vcpus in a virtual core to be ready to run before we run the virtual core. However, that causes problems on reset, because reset stops all vcpus except vcpu 0, and can also reduce throughput since all four threads in a virtual core have to wait whenever any one of them hits a hypervisor page fault. This relaxes the policy, allowing the virtual core to run as soon as any vcpu in it is runnable. With this, the KVMPPC_VCPU_STOPPED state and the KVMPPC_VCPU_BUSY_IN_HOST state have been combined into a single KVMPPC_VCPU_NOTREADY state, since we no longer need to distinguish between them. Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/kvm_host.h | 5 +-- arch/powerpc/kvm/book3s_hv.c | 74 ++++++++++++++++++----------------- 2 files changed, 40 insertions(+), 39 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 218534d..1e8cbd1 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -563,9 +563,8 @@ struct kvm_vcpu_arch { }; /* Values for vcpu->arch.state */ -#define KVMPPC_VCPU_STOPPED 0 -#define KVMPPC_VCPU_BUSY_IN_HOST 1 -#define KVMPPC_VCPU_RUNNABLE 2 +#define KVMPPC_VCPU_NOTREADY 0 +#define KVMPPC_VCPU_RUNNABLE 1 /* Values for vcpu->arch.io_gpr */ #define KVM_MMIO_REG_MASK 0x001f diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 8e84625..dc34a69 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -669,10 +669,7 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id) kvmppc_mmu_book3s_hv_init(vcpu); - /* - * We consider the vcpu stopped until we see the first run ioctl for it. - */ - vcpu->arch.state = KVMPPC_VCPU_STOPPED; + vcpu->arch.state = KVMPPC_VCPU_NOTREADY; init_waitqueue_head(&vcpu->arch.cpu_run); @@ -759,9 +756,8 @@ static void kvmppc_remove_runnable(struct kvmppc_vcore *vc, { if (vcpu->arch.state != KVMPPC_VCPU_RUNNABLE) return; - vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST; + vcpu->arch.state = KVMPPC_VCPU_NOTREADY; --vc->n_runnable; - ++vc->n_busy; list_del(&vcpu->arch.run_list); } @@ -1062,7 +1058,6 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) { int n_ceded; - int prev_state; struct kvmppc_vcore *vc; struct kvm_vcpu *v, *vn; @@ -1079,7 +1074,6 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) vcpu->arch.ceded = 0; vcpu->arch.run_task = current; vcpu->arch.kvm_run = kvm_run; - prev_state = vcpu->arch.state; vcpu->arch.state = KVMPPC_VCPU_RUNNABLE; list_add_tail(&vcpu->arch.run_list, &vc->runnable_threads); ++vc->n_runnable; @@ -1089,35 +1083,26 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) * If the vcore is already running, we may be able to start * this thread straight away and have it join in. */ - if (prev_state == KVMPPC_VCPU_STOPPED) { + if (!signal_pending(current)) { if (vc->vcore_state == VCORE_RUNNING && VCORE_EXIT_COUNT(vc) == 0) { vcpu->arch.ptid = vc->n_runnable - 1; kvmppc_create_dtl_entry(vcpu, vc); kvmppc_start_thread(vcpu); + } else if (vc->vcore_state == VCORE_SLEEPING) { + wake_up(&vc->wq); } - } else if (prev_state == KVMPPC_VCPU_BUSY_IN_HOST) - --vc->n_busy; + } while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE && !signal_pending(current)) { - if (vc->n_busy || vc->vcore_state != VCORE_INACTIVE) { + if (vc->vcore_state != VCORE_INACTIVE) { spin_unlock(&vc->lock); kvmppc_wait_for_exec(vcpu, TASK_INTERRUPTIBLE); spin_lock(&vc->lock); continue; } - vc->runner = vcpu; - n_ceded = 0; - list_for_each_entry(v, &vc->runnable_threads, arch.run_list) - if (!v->arch.pending_exceptions) - n_ceded += v->arch.ceded; - if (n_ceded == vc->n_runnable) - kvmppc_vcore_blocked(vc); - else - kvmppc_run_core(vc); - list_for_each_entry_safe(v, vn, &vc->runnable_threads, arch.run_list) { kvmppc_core_prepare_to_enter(v); @@ -1129,23 +1114,40 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) wake_up(&v->arch.cpu_run); } } + if (!vc->n_runnable || vcpu->arch.state != KVMPPC_VCPU_RUNNABLE) + break; + vc->runner = vcpu; + n_ceded = 0; + list_for_each_entry(v, &vc->runnable_threads, arch.run_list) + if (!v->arch.pending_exceptions) + n_ceded += v->arch.ceded; + if (n_ceded == vc->n_runnable) + kvmppc_vcore_blocked(vc); + else + kvmppc_run_core(vc); vc->runner = NULL; } - if (signal_pending(current)) { - while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE && - (vc->vcore_state == VCORE_RUNNING || - vc->vcore_state == VCORE_EXITING)) { - spin_unlock(&vc->lock); - kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE); - spin_lock(&vc->lock); - } - if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) { - kvmppc_remove_runnable(vc, vcpu); - vcpu->stat.signal_exits++; - kvm_run->exit_reason = KVM_EXIT_INTR; - vcpu->arch.ret = -EINTR; - } + while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE && + (vc->vcore_state == VCORE_RUNNING || + vc->vcore_state == VCORE_EXITING)) { + spin_unlock(&vc->lock); + kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE); + spin_lock(&vc->lock); + } + + if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) { + kvmppc_remove_runnable(vc, vcpu); + vcpu->stat.signal_exits++; + kvm_run->exit_reason = KVM_EXIT_INTR; + vcpu->arch.ret = -EINTR; + } + + if (vc->n_runnable && vc->vcore_state == VCORE_INACTIVE) { + /* Wake up some vcpu to run the core */ + v = list_first_entry(&vc->runnable_threads, + struct kvm_vcpu, arch.run_list); + wake_up(&v->arch.cpu_run); } spin_unlock(&vc->lock);