Commit 2b519b57 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

x86/kvm: Don't bother __pv_cpu_mask when !CONFIG_SMP 



Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's
move it inside CONFIG_SMP. In addition, we can avoid define and
alloc __pv_cpu_mask when !CONFIG_SMP and get rid of 'alloc' variable
in kvm_alloc_cpumask.

Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Message-Id: <1617941911-5338-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4c6654bd

arch/x86/kernel/kvm.c

+55 −63
Original line number Diff line number Diff line
@@ -451,6 +451,10 @@ static void __init sev_map_percpu_data(void) 
	}

}



#ifdef CONFIG_SMP



static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);



static bool pv_tlb_flush_supported(void)

{

	return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
@@ -458,10 +462,6 @@ static bool pv_tlb_flush_supported(void) 
		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));

}



static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);



#ifdef CONFIG_SMP



static bool pv_ipi_supported(void)

{

	return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);
@@ -574,6 +574,49 @@ static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) 
	}

}



static void kvm_flush_tlb_others(const struct cpumask *cpumask,

			const struct flush_tlb_info *info)

{

	u8 state;

	int cpu;

	struct kvm_steal_time *src;

	struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);



	cpumask_copy(flushmask, cpumask);

	/*

	 * We have to call flush only on online vCPUs. And

	 * queue flush_on_enter for pre-empted vCPUs

	 */

	for_each_cpu(cpu, flushmask) {

		src = &per_cpu(steal_time, cpu);

		state = READ_ONCE(src->preempted);

		if ((state & KVM_VCPU_PREEMPTED)) {

			if (try_cmpxchg(&src->preempted, &state,

					state | KVM_VCPU_FLUSH_TLB))

				__cpumask_clear_cpu(cpu, flushmask);

		}

	}



	native_flush_tlb_others(flushmask, info);

}



static __init int kvm_alloc_cpumask(void)

{

	int cpu;



	if (!kvm_para_available() || nopv)

		return 0;



	if (pv_tlb_flush_supported() || pv_ipi_supported())

		for_each_possible_cpu(cpu) {

			zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),

				GFP_KERNEL, cpu_to_node(cpu));

		}



	return 0;

}

arch_initcall(kvm_alloc_cpumask);



static void __init kvm_smp_prepare_boot_cpu(void)

{

	/*
@@ -611,33 +654,8 @@ static int kvm_cpu_down_prepare(unsigned int cpu) 
	local_irq_enable();

	return 0;

}

#endif



static void kvm_flush_tlb_others(const struct cpumask *cpumask,

			const struct flush_tlb_info *info)

{

	u8 state;

	int cpu;

	struct kvm_steal_time *src;

	struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);



	cpumask_copy(flushmask, cpumask);

	/*

	 * We have to call flush only on online vCPUs. And

	 * queue flush_on_enter for pre-empted vCPUs

	 */

	for_each_cpu(cpu, flushmask) {

		src = &per_cpu(steal_time, cpu);

		state = READ_ONCE(src->preempted);

		if ((state & KVM_VCPU_PREEMPTED)) {

			if (try_cmpxchg(&src->preempted, &state,

					state | KVM_VCPU_FLUSH_TLB))

				__cpumask_clear_cpu(cpu, flushmask);

		}

	}



	native_flush_tlb_others(flushmask, info);

}

#endif



static void __init kvm_guest_init(void)

{
@@ -653,12 +671,6 @@ static void __init kvm_guest_init(void) 
		pv_ops.time.steal_clock = kvm_steal_clock;

	}



	if (pv_tlb_flush_supported()) {

		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;

		pv_ops.mmu.tlb_remove_table = tlb_remove_table;

		pr_info("KVM setup pv remote TLB flush\n");

	}



	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))

		apic_set_eoi_write(kvm_guest_apic_eoi_write);
@@ -668,6 +680,12 @@ static void __init kvm_guest_init(void) 
	}



#ifdef CONFIG_SMP

	if (pv_tlb_flush_supported()) {

		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;

		pv_ops.mmu.tlb_remove_table = tlb_remove_table;

		pr_info("KVM setup pv remote TLB flush\n");

	}



	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;

	if (pv_sched_yield_supported()) {

		smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
@@ -734,7 +752,7 @@ static uint32_t __init kvm_detect(void) 


static void __init kvm_apic_init(void)

{

#if defined(CONFIG_SMP)

#ifdef CONFIG_SMP

	if (pv_ipi_supported())

		kvm_setup_pv_ipi();

#endif
@@ -794,32 +812,6 @@ static __init int activate_jump_labels(void) 
}

arch_initcall(activate_jump_labels);



static __init int kvm_alloc_cpumask(void)

{

	int cpu;

	bool alloc = false;



	if (!kvm_para_available() || nopv)

		return 0;



	if (pv_tlb_flush_supported())

		alloc = true;



#if defined(CONFIG_SMP)

	if (pv_ipi_supported())

		alloc = true;

#endif



	if (alloc)

		for_each_possible_cpu(cpu) {

			zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),

				GFP_KERNEL, cpu_to_node(cpu));

		}



	return 0;

}

arch_initcall(kvm_alloc_cpumask);



#ifdef CONFIG_PARAVIRT_SPINLOCKS



/* Kick a cpu by its apicid. Used to wake up a halted vcpu */