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KVM: x86: simplify kvm_apic_map
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recalculate_apic_map() uses two passes over all VCPUs.  This is a relic
from time when we selected a global mode in the first pass and set up
the optimized table in the second pass (to have a consistent mode).

Recent changes made mixed mode unoptimized and we can do it in one pass.
Format of logical MDA is a function of the mode, so we encode it in
apic_logical_id() and drop obsoleted variables from the struct.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <1423766494-26150-5-git-send-email-rkrcmar@redhat.com>
[Add lid_bits temporary in apic_logical_id. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Radim Krčmář authored and Paolo Bonzini committed Apr 8, 2015
1 parent 3548a25 commit 3b5a5ff
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Showing 3 changed files with 28 additions and 68 deletions.
3 changes: 0 additions & 3 deletions arch/x86/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -562,9 +562,6 @@ struct kvm_arch_memory_slot {
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;
struct kvm_lapic *phys_map[256];
/* first index is cluster id second is cpu id in a cluster */
struct kvm_lapic *logical_map[16][16];
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78 changes: 28 additions & 50 deletions arch/x86/kvm/lapic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,20 @@ static inline bool kvm_apic_logical_map_valid(struct kvm_apic_map *map)
return !(map->mode & (map->mode - 1));
}

static inline void
apic_logical_id(struct kvm_apic_map *map, u32 dest_id, u16 *cid, u16 *lid)
{
unsigned lid_bits;

BUILD_BUG_ON(KVM_APIC_MODE_XAPIC_CLUSTER != 4);
BUILD_BUG_ON(KVM_APIC_MODE_XAPIC_FLAT != 8);
BUILD_BUG_ON(KVM_APIC_MODE_X2APIC != 16);
lid_bits = map->mode;

*cid = dest_id >> lid_bits;
*lid = dest_id & ((1 << lid_bits) - 1);
}

static void recalculate_apic_map(struct kvm *kvm)
{
struct kvm_apic_map *new, *old = NULL;
Expand All @@ -154,49 +168,6 @@ static void recalculate_apic_map(struct kvm *kvm)
if (!new)
goto out;

new->ldr_bits = 8;
/* flat mode is default */
new->cid_shift = 8;
new->cid_mask = 0;
new->lid_mask = 0xff;

kvm_for_each_vcpu(i, vcpu, kvm) {
struct kvm_lapic *apic = vcpu->arch.apic;

if (!kvm_apic_present(vcpu))
continue;

if (apic_x2apic_mode(apic)) {
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;
}
}

/*
* All APICs have to be configured in the same mode by an OS.
* We take advatage of this while building logical id loockup
* table. After reset APICs are in software disabled mode, so if
* we find apic with different setting we assume this is the mode
* OS wants all apics to be in; build lookup table accordingly.
*/
if (kvm_apic_sw_enabled(apic))
break;
}

kvm_for_each_vcpu(i, vcpu, kvm) {
struct kvm_lapic *apic = vcpu->arch.apic;
u16 cid, lid;
Expand All @@ -207,15 +178,25 @@ static void recalculate_apic_map(struct kvm *kvm)

aid = kvm_apic_id(apic);
ldr = kvm_apic_get_reg(apic, APIC_LDR);
cid = apic_cluster_id(new, ldr);
lid = apic_logical_id(new, ldr);

if (aid < ARRAY_SIZE(new->phys_map))
new->phys_map[aid] = apic;

if (!kvm_apic_logical_map_valid(new));
if (apic_x2apic_mode(apic)) {
new->mode |= KVM_APIC_MODE_X2APIC;
} else if (ldr) {
ldr = GET_APIC_LOGICAL_ID(ldr);
if (kvm_apic_get_reg(apic, APIC_DFR) == APIC_DFR_FLAT)
new->mode |= KVM_APIC_MODE_XAPIC_FLAT;
else
new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;
}

if (!kvm_apic_logical_map_valid(new))
continue;

apic_logical_id(new, ldr, &cid, &lid);

if (lid && cid < ARRAY_SIZE(new->logical_map))
new->logical_map[cid][ffs(lid) - 1] = apic;
}
Expand Down Expand Up @@ -732,23 +713,20 @@ 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;

if (!kvm_apic_logical_map_valid(map)) {
ret = false;
goto out;
}

cid = apic_cluster_id(map, mda);
apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap);

if (cid >= ARRAY_SIZE(map->logical_map))
goto out;

dst = map->logical_map[cid];

bitmap = apic_logical_id(map, mda);

if (irq->delivery_mode == APIC_DM_LOWEST) {
int l = -1;
for_each_set_bit(i, &bitmap, 16) {
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15 changes: 0 additions & 15 deletions arch/x86/kvm/lapic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -148,21 +148,6 @@ static inline bool kvm_apic_vid_enabled(struct kvm *kvm)
return kvm_x86_ops->vm_has_apicv(kvm);
}

static inline u16 apic_cluster_id(struct kvm_apic_map *map, u32 ldr)
{
u16 cid;
ldr >>= 32 - map->ldr_bits;
cid = (ldr >> map->cid_shift) & map->cid_mask;

return cid;
}

static inline u16 apic_logical_id(struct kvm_apic_map *map, u32 ldr)
{
ldr >>= (32 - map->ldr_bits);
return ldr & map->lid_mask;
}

static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu)
{
return vcpu->arch.apic->pending_events;
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