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Commit aaffcfd1 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: X86: Implement PV IPIs in linux guest 



Implement paravirtual apic hooks to enable PV IPIs for KVM if the "send IPI"
hypercall is available.  The hypercall lets a guest send IPIs, with
at most 128 destinations per hypercall in 64-bit mode and 64 vCPUs per
hypercall in 32-bit mode.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d63bae07

arch/x86/include/uapi/asm/kvm_para.h

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#define KVM_FEATURE_PV_UNHALT		7

#define KVM_FEATURE_PV_TLB_FLUSH	9

#define KVM_FEATURE_ASYNC_PF_VMEXIT	10

#define KVM_FEATURE_PV_SEND_IPI	11



#define KVM_HINTS_REALTIME      0

arch/x86/kernel/kvm.c

+96 −0
Original line number Diff line number Diff line
@@ -454,6 +454,98 @@ static void __init sev_map_percpu_data(void) 
}



#ifdef CONFIG_SMP

#define KVM_IPI_CLUSTER_SIZE	(2 * BITS_PER_LONG)



static void __send_ipi_mask(const struct cpumask *mask, int vector)

{

	unsigned long flags;

	int cpu, apic_id, icr;

	int min = 0, max = 0;

#ifdef CONFIG_X86_64

	__uint128_t ipi_bitmap = 0;

#else

	u64 ipi_bitmap = 0;

#endif



	if (cpumask_empty(mask))

		return;



	local_irq_save(flags);



	switch (vector) {

	default:

		icr = APIC_DM_FIXED | vector;

		break;

	case NMI_VECTOR:

		icr = APIC_DM_NMI;

		break;

	}



	for_each_cpu(cpu, mask) {

		apic_id = per_cpu(x86_cpu_to_apicid, cpu);

		if (!ipi_bitmap) {

			min = max = apic_id;

		} else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {

			ipi_bitmap <<= min - apic_id;

			min = apic_id;

		} else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {

			max = apic_id < max ? max : apic_id;

		} else {

			kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,

				(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);

			min = max = apic_id;

			ipi_bitmap = 0;

		}

		__set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);

	}



	if (ipi_bitmap) {

		kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,

			(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);

	}



	local_irq_restore(flags);

}



static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)

{

	__send_ipi_mask(mask, vector);

}



static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)

{

	unsigned int this_cpu = smp_processor_id();

	struct cpumask new_mask;

	const struct cpumask *local_mask;



	cpumask_copy(&new_mask, mask);

	cpumask_clear_cpu(this_cpu, &new_mask);

	local_mask = &new_mask;

	__send_ipi_mask(local_mask, vector);

}



static void kvm_send_ipi_allbutself(int vector)

{

	kvm_send_ipi_mask_allbutself(cpu_online_mask, vector);

}



static void kvm_send_ipi_all(int vector)

{

	__send_ipi_mask(cpu_online_mask, vector);

}



/*

 * Set the IPI entry points

 */

static void kvm_setup_pv_ipi(void)

{

	apic->send_IPI_mask = kvm_send_ipi_mask;

	apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;

	apic->send_IPI_allbutself = kvm_send_ipi_allbutself;

	apic->send_IPI_all = kvm_send_ipi_all;

	pr_info("KVM setup pv IPIs\n");

}



static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)

{

	native_smp_prepare_cpus(max_cpus);
@@ -626,6 +718,10 @@ static uint32_t __init kvm_detect(void) 


static void __init kvm_apic_init(void)

{

#if defined(CONFIG_SMP)

	if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))

		kvm_setup_pv_ipi();

#endif

}



static void __init kvm_init_platform(void)

include/uapi/linux/kvm_para.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#define KVM_HC_MIPS_EXIT_VM		7

#define KVM_HC_MIPS_CONSOLE_OUTPUT	8

#define KVM_HC_CLOCK_PAIRING		9

#define KVM_HC_SEND_IPI		10



/*

 * hypercalls use architecture specific