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Commit 52004014 authored by Feng Wu's avatar Feng Wu Committed by Paolo Bonzini
Browse files

KVM: x86: Use vector-hashing to deliver lowest-priority interrupts 



Use vector-hashing to deliver lowest-priority interrupts, As an
example, modern Intel CPUs in server platform use this method to
handle lowest-priority interrupts.

Signed-off-by: default avatarFeng Wu <feng.wu@intel.com>
Reviewed-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 23a1c257

arch/x86/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -754,6 +754,8 @@ struct kvm_arch { 


	bool irqchip_split;

	u8 nr_reserved_ioapic_pins;



	bool disabled_lapic_found;

};



struct kvm_vm_stat {

arch/x86/kvm/irq_comm.c

+21 −4
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include "lapic.h"



#include "hyperv.h"

#include "x86.h"



static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,

			   struct kvm *kvm, int irq_source_id, int level,
@@ -57,6 +58,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, 
{

	int i, r = -1;

	struct kvm_vcpu *vcpu, *lowest = NULL;

	unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)];

	unsigned int dest_vcpus = 0;



	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&

			kvm_lowest_prio_delivery(irq)) {
@@ -67,6 +70,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, 
	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))

		return r;



	memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap));



	kvm_for_each_vcpu(i, vcpu, kvm) {

		if (!kvm_apic_present(vcpu))

			continue;
@@ -80,11 +85,23 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, 
				r = 0;

			r += kvm_apic_set_irq(vcpu, irq, dest_map);

		} else if (kvm_lapic_enabled(vcpu)) {

			if (!kvm_vector_hashing_enabled()) {

				if (!lowest)

					lowest = vcpu;

				else if (kvm_apic_compare_prio(vcpu, lowest) < 0)

					lowest = vcpu;

			} else {

				__set_bit(i, dest_vcpu_bitmap);

				dest_vcpus++;

			}

		}

	}



	if (dest_vcpus != 0) {

		int idx = kvm_vector_to_index(irq->vector, dest_vcpus,

					dest_vcpu_bitmap, KVM_MAX_VCPUS);



		lowest = kvm_get_vcpu(kvm, idx);

	}



	if (lowest)

arch/x86/kvm/lapic.c

+47 −3
Original line number Diff line number Diff line
@@ -675,6 +675,22 @@ bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source, 
	}

}



int kvm_vector_to_index(u32 vector, u32 dest_vcpus,

		       const unsigned long *bitmap, u32 bitmap_size)

{

	u32 mod;

	int i, idx = -1;



	mod = vector % dest_vcpus;



	for (i = 0; i <= mod; i++) {

		idx = find_next_bit(bitmap, bitmap_size, idx + 1);

		BUG_ON(idx == bitmap_size);

	}



	return idx;

}



bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,

		struct kvm_lapic_irq *irq, int *r, unsigned long *dest_map)

{
@@ -727,21 +743,49 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, 


		dst = map->logical_map[cid];



		if (kvm_lowest_prio_delivery(irq)) {

		if (!kvm_lowest_prio_delivery(irq))

			goto set_irq;



		if (!kvm_vector_hashing_enabled()) {

			int l = -1;

			for_each_set_bit(i, &bitmap, 16) {

				if (!dst[i])

					continue;

				if (l < 0)

					l = i;

				else if (kvm_apic_compare_prio(dst[i]->vcpu, dst[l]->vcpu) < 0)

				else if (kvm_apic_compare_prio(dst[i]->vcpu,

							dst[l]->vcpu) < 0)

					l = i;

			}



			bitmap = (l >= 0) ? 1 << l : 0;

		} else {

			int idx;

			unsigned int dest_vcpus;



			dest_vcpus = hweight16(bitmap);

			if (dest_vcpus == 0)

				goto out;



			idx = kvm_vector_to_index(irq->vector,

				dest_vcpus, &bitmap, 16);



			/*

			 * We may find a hardware disabled LAPIC here, if that

			 * is the case, print out a error message once for each

			 * guest and return.

			 */

			if (!dst[idx] && !kvm->arch.disabled_lapic_found) {

				kvm->arch.disabled_lapic_found = true;

				printk(KERN_INFO

					"Disabled LAPIC found during irq injection\n");

				goto out;

			}



			bitmap = (idx >= 0) ? 1 << idx : 0;

		}

	}



set_irq:

	for_each_set_bit(i, &bitmap, 16) {

		if (!dst[i])

			continue;

arch/x86/kvm/lapic.h

+2 −0
Original line number Diff line number Diff line
@@ -175,4 +175,6 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu); 


bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,

			struct kvm_vcpu **dest_vcpu);

int kvm_vector_to_index(u32 vector, u32 dest_vcpus,

			const unsigned long *bitmap, u32 bitmap_size);

#endif

arch/x86/kvm/x86.c

+9 −0
Original line number Diff line number Diff line
@@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR); 
unsigned int __read_mostly lapic_timer_advance_ns = 0;

module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR);



static bool __read_mostly vector_hashing = true;

module_param(vector_hashing, bool, S_IRUGO);



static bool __read_mostly backwards_tsc_observed = false;



#define KVM_NR_SHARED_MSRS 16
@@ -8364,6 +8367,12 @@ int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq, 
	return kvm_x86_ops->update_pi_irte(kvm, host_irq, guest_irq, set);

}



bool kvm_vector_hashing_enabled(void)

{

	return vector_hashing;

}

EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled);



EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);

EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);

EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);