From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wanpeng Li Subject: [PATCH v3 3/3] KVM: X86: Don't use PV TLB flush with dedicated vCPUs and steal time disabled Date: Sun, 11 Feb 2018 11:29:46 +0800 Message-ID: <1518319786-1466-4-git-send-email-wanpengli@tencent.com> References: <1518319786-1466-1-git-send-email-wanpengli@tencent.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Eduardo Habkost To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Return-path: In-Reply-To: <1518319786-1466-1-git-send-email-wanpengli@tencent.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org From: Wanpeng Li vCPUs are very unlikely to get preempted when they are the only task running on a CPU. PV TLB flush is slower that the native flush in that case. In addition, avoid traversing all the cpus for pv tlb flush when steal time is disabled since pv tlb flush depends on the field in steal time for shared data. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Eduardo Habkost Signed-off-by: Wanpeng Li --- arch/x86/kernel/kvm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index c5566d9..285822f 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -545,7 +545,9 @@ static void __init kvm_guest_init(void) pv_time_ops.steal_clock = kvm_steal_clock; } - if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH)) + if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && + !kvm_para_has_feature(KVM_HINTS_DEDICATED) && + !kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others; if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) @@ -638,7 +640,9 @@ static __init int kvm_setup_pv_tlb_flush(void) { int cpu; - if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH)) { + if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && + !kvm_para_has_feature(KVM_HINTS_DEDICATED) && + !kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { for_each_possible_cpu(cpu) { zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), GFP_KERNEL, cpu_to_node(cpu)); -- 2.7.4