KVM: X86: Don't use PV TLB flush with dedicated physical CPUs

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, so disable it.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f803e89..4ccbff6 100644 (file)
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -546,6 +546,7 @@ static void __init kvm_guest_init(void)
        }
 
        if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
+           !kvm_para_has_hint(KVM_HINTS_DEDICATED) &&
            !kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
                pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
 
@@ -640,6 +641,7 @@ static __init int kvm_setup_pv_tlb_flush(void)
        int cpu;
 
        if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
+           !kvm_para_has_hint(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),