Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756303Ab2FDFI5 (ORCPT ); Mon, 4 Jun 2012 01:08:57 -0400 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:57731 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756078Ab2FDFIy (ORCPT ); Mon, 4 Jun 2012 01:08:54 -0400 Subject: [PATCH v2 5/7] KVM: Introduce PV kick in flush tlb To: peterz@infradead.org, mingo@elte.hu, mtosatti@redhat.com, avi@redhat.com From: "Nikunj A. Dadhania" Cc: raghukt@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, jeremy@goop.org, vatsa@linux.vnet.ibm.com, hpa@zytor.com Date: Mon, 04 Jun 2012 10:38:17 +0530 Message-ID: <20120604050755.4560.24727.stgit@abhimanyu.in.ibm.com> In-Reply-To: <20120604050223.4560.2874.stgit@abhimanyu.in.ibm.com> References: <20120604050223.4560.2874.stgit@abhimanyu.in.ibm.com> User-Agent: StGit/0.16-2-g0d85 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit x-cbid: 12060405-5816-0000-0000-000002FD78E7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2961 Lines: 96 In place of looping continuously introduce a halt if we do not succeed after some time. For vcpus that were running an IPI is sent. In case, it went to sleep between this, we will be doing flush_on_enter(harmless). But as a flush IPI was already sent, that will be processed in ipi handler, this might result into something undesireable, i.e. It might clear the flush_mask of a new request. So after sending an IPI and waiting for a while, do a halt and wait for a kick from the last vcpu. Signed-off-by: Srivatsa Vaddagiri Signed-off-by: Nikunj A. Dadhania --- arch/x86/mm/tlb.c | 25 +++++++++++++++++-------- 1 files changed, 17 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index f5dacdd..2c686bf 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -43,6 +43,8 @@ union smp_flush_state { struct { struct mm_struct *flush_mm; unsigned long flush_va; + int sender_cpu; + unsigned int need_kick; raw_spinlock_t tlbstate_lock; DECLARE_BITMAP(flush_cpumask, NR_CPUS); }; @@ -167,6 +169,11 @@ out: smp_mb__before_clear_bit(); cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask)); smp_mb__after_clear_bit(); + if (f->need_kick && cpumask_empty(to_cpumask(f->flush_cpumask))) { + f->need_kick = 0; + smp_wmb(); + kvm_kick_cpu(f->sender_cpu); + } inc_irq_stat(irq_tlb_count); } @@ -222,15 +229,17 @@ void kvm_flush_tlb_others(const struct cpumask *cpumask, if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS) raw_spin_lock(&f->tlbstate_lock); + cpu = smp_processor_id(); f->flush_mm = mm; f->flush_va = va; - if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) { + f->sender_cpu = cpu; + f->need_kick = 0; + if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(cpu))) { /* * We have to send the IPI only to online vCPUs * affected. And queue flush_on_enter for pre-empted * vCPUs */ -again: for_each_cpu(cpu, to_cpumask(f->flush_cpumask)) { v_state = &per_cpu(vcpu_state, cpu); @@ -242,9 +251,6 @@ again: } } - if (cpumask_empty(to_cpumask(f->flush_cpumask))) - goto out; - apic->send_IPI_mask(to_cpumask(f->flush_cpumask), INVALIDATE_TLB_VECTOR_START + sender); @@ -252,10 +258,13 @@ again: while (!cpumask_empty(to_cpumask(f->flush_cpumask)) && --loop) cpu_relax(); - if (!cpumask_empty(to_cpumask(f->flush_cpumask))) - goto again; + if (!loop) { + f->need_kick = 1; + smp_mb(); + while (!cpumask_empty(to_cpumask(f->flush_cpumask))) + halt(); + } } -out: f->flush_mm = NULL; f->flush_va = 0; if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/