Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3548a259 authored by Radim Krčmář's avatar Radim Krčmář Committed by Paolo Bonzini
Browse files

KVM: x86: avoid logical_map when it is invalid 



We want to support mixed modes and the easiest solution is to avoid
optimizing those weird and unlikely scenarios.

Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Message-Id: <1423766494-26150-4-git-send-email-rkrcmar@redhat.com>
[Add comment above KVM_APIC_MODE_* defines. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9ea369b0

arch/x86/include/asm/kvm_host.h

+12 −0
Original line number Diff line number Diff line
@@ -548,8 +548,20 @@ struct kvm_arch_memory_slot { 
	struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];

};



/*

 * We use as the mode the number of bits allocated in the LDR for the

 * logical processor ID.  It happens that these are all powers of two.

 * This makes it is very easy to detect cases where the APICs are

 * configured for multiple modes; in that case, we cannot use the map and

 * hence cannot use kvm_irq_delivery_to_apic_fast either.

 */

#define KVM_APIC_MODE_XAPIC_CLUSTER          4

#define KVM_APIC_MODE_XAPIC_FLAT             8

#define KVM_APIC_MODE_X2APIC                16



struct kvm_apic_map {

	struct rcu_head rcu;

	u8 mode;

	u8 ldr_bits;

	/* fields bellow are used to decode ldr values in different modes */

	u32 cid_shift, cid_mask, lid_mask;

arch/x86/kvm/lapic.c

+23 −1
Original line number Diff line number Diff line
@@ -133,6 +133,14 @@ static inline int kvm_apic_id(struct kvm_lapic *apic) 
	return (kvm_apic_get_reg(apic, APIC_ID) >> 24) & 0xff;

}



/* The logical map is definitely wrong if we have multiple

 * modes at the same time.  (Physical map is always right.)

 */

static inline bool kvm_apic_logical_map_valid(struct kvm_apic_map *map)

{

	return !(map->mode & (map->mode - 1));

}



static void recalculate_apic_map(struct kvm *kvm)

{

	struct kvm_apic_map *new, *old = NULL;
@@ -162,16 +170,19 @@ static void recalculate_apic_map(struct kvm *kvm) 
			new->ldr_bits = 32;

			new->cid_shift = 16;

			new->cid_mask = new->lid_mask = 0xffff;

			new->mode |= KVM_APIC_MODE_X2APIC;

		} else if (kvm_apic_get_reg(apic, APIC_LDR)) {

			if (kvm_apic_get_reg(apic, APIC_DFR) ==

							APIC_DFR_CLUSTER) {

				new->cid_shift = 4;

				new->cid_mask = 0xf;

				new->lid_mask = 0xf;

				new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;

			} else {

				new->cid_shift = 8;

				new->cid_mask = 0;

				new->lid_mask = 0xff;

				new->mode |= KVM_APIC_MODE_XAPIC_FLAT;

			}

		}
@@ -201,6 +212,10 @@ static void recalculate_apic_map(struct kvm *kvm) 


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

			new->phys_map[aid] = apic;



		if (!kvm_apic_logical_map_valid(new));

			continue;



		if (lid && cid < ARRAY_SIZE(new->logical_map))

			new->logical_map[cid][ffs(lid) - 1] = apic;

	}
@@ -718,7 +733,14 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, 
		dst = &map->phys_map[irq->dest_id];

	} else {

		u32 mda = irq->dest_id << (32 - map->ldr_bits);

		u16 cid = apic_cluster_id(map, mda);

		u16 cid;



		if (!kvm_apic_logical_map_valid(map)) {

			ret = false;

			goto out;

		}



		cid = apic_cluster_id(map, mda);



		if (cid >= ARRAY_SIZE(map->logical_map))

			goto out;