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Commit 0ca52e7b authored by Radim Krčmář's avatar Radim Krčmář Committed by Paolo Bonzini
Browse files

KVM: x86: dynamic kvm_apic_map 



x2APIC supports up to 2^32-1 LAPICs, but most guest in coming years will
probably has fewer VCPUs.  Dynamic size saves memory at the cost of
turning one constant into a variable.

apic_map mutex had to be moved before allocation to avoid races with cpu
hotplug.

Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e45115b6

arch/x86/include/asm/kvm_host.h

+2 −1
Original line number Diff line number Diff line
@@ -682,11 +682,12 @@ struct kvm_arch_memory_slot { 
struct kvm_apic_map {

	struct rcu_head rcu;

	u8 mode;

	struct kvm_lapic *phys_map[256];

	u32 max_apic_id;

	union {

		struct kvm_lapic *xapic_flat_map[8];

		struct kvm_lapic *xapic_cluster_map[16][4];

	};

	struct kvm_lapic *phys_map[];

};



/* Hyper-V emulation context */

arch/x86/kvm/lapic.c

+13 −5
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map, 
	switch (map->mode) {

	case KVM_APIC_MODE_X2APIC: {

		u32 offset = (dest_id >> 16) * 16;

		u32 max_apic_id = ARRAY_SIZE(map->phys_map) - 1;

		u32 max_apic_id = map->max_apic_id;



		if (offset <= max_apic_id) {

			u8 cluster_size = min(max_apic_id - offset + 1, 16U);
@@ -152,14 +152,22 @@ static void recalculate_apic_map(struct kvm *kvm) 
	struct kvm_apic_map *new, *old = NULL;

	struct kvm_vcpu *vcpu;

	int i;



	new = kzalloc(sizeof(struct kvm_apic_map), GFP_KERNEL);

	u32 max_id = 255;



	mutex_lock(&kvm->arch.apic_map_lock);



	kvm_for_each_vcpu(i, vcpu, kvm)

		if (kvm_apic_present(vcpu))

			max_id = max(max_id, kvm_apic_id(vcpu->arch.apic));



	new = kzalloc(sizeof(struct kvm_apic_map) +

	              sizeof(struct kvm_lapic *) * (max_id + 1), GFP_KERNEL);



	if (!new)

		goto out;



	new->max_apic_id = max_id;



	kvm_for_each_vcpu(i, vcpu, kvm) {

		struct kvm_lapic *apic = vcpu->arch.apic;

		struct kvm_lapic **cluster;
@@ -172,7 +180,7 @@ static void recalculate_apic_map(struct kvm *kvm) 
		aid = kvm_apic_id(apic);

		ldr = kvm_lapic_get_reg(apic, APIC_LDR);



		if (aid < ARRAY_SIZE(new->phys_map))

		if (aid <= new->max_apic_id)

			new->phys_map[aid] = apic;



		if (apic_x2apic_mode(apic)) {
@@ -710,7 +718,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, 
		return false;



	if (irq->dest_mode == APIC_DEST_PHYSICAL) {

		if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) {

		if (irq->dest_id > map->max_apic_id) {

			*bitmap = 0;

		} else {

			*dst = &map->phys_map[irq->dest_id];

arch/x86/kvm/lapic.h

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu) 
	return lapic_in_kernel(vcpu) && test_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);

}



static inline int kvm_apic_id(struct kvm_lapic *apic)

static inline u32 kvm_apic_id(struct kvm_lapic *apic)

{

	return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;

}