From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760770Ab2D0Q1l (ORCPT ); Fri, 27 Apr 2012 12:27:41 -0400 Received: from e28smtp05.in.ibm.com ([122.248.162.5]:39896 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760750Ab2D0Q1j (ORCPT ); Fri, 27 Apr 2012 12:27:39 -0400 Subject: [RFC PATCH v1 5/5] KVM: Introduce PV kick in flush tlb To: peterz@infradead.org, mingo@elte.hu From: "Nikunj A. Dadhania" Cc: jeremy@goop.org, mtosatti@redhat.com, kvm@vger.kernel.org, x86@kernel.org, vatsa@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, avi@redhat.com, hpa@zytor.com Date: Fri, 27 Apr 2012 21:57:05 +0530 Message-ID: <20120427162646.27082.6948.stgit@abhimanyu> In-Reply-To: <20120427161727.27082.43096.stgit@abhimanyu> References: <20120427161727.27082.43096.stgit@abhimanyu> User-Agent: StGit/0.16-2-g0d85 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit x-cbid: 12042716-8256-0000-0000-0000022A82A0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 27 +++++++++++++++++++-------- 1 files changed, 19 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 91ae34e..2a20e59 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); }; @@ -71,6 +73,8 @@ void leave_mm(int cpu) EXPORT_SYMBOL_GPL(leave_mm); DECLARE_PER_CPU(struct kvm_vcpu_state, vcpu_state) __aligned(64); +extern void kvm_kick_cpu(int cpu); + /* * * The flush IPI assumes that a thread switch happens in this order: @@ -168,6 +172,11 @@ 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); } @@ -219,15 +228,17 @@ 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); @@ -239,9 +250,6 @@ 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); @@ -249,10 +257,13 @@ 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)