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authorGleb Natapov <gleb@redhat.com>2012-09-13 17:19:24 +0300
committerAvi Kivity <avi@redhat.com>2012-09-20 15:05:26 +0300
commit1e08ec4a130e2745d96df169e67c58df98a07311 (patch)
tree362647f5b0bac59e7fe93ce66775afac2cd7da79
parent1d86b5cc4c6d9a1be1458be3701ac9c915a9706f (diff)
downloadvexpress-lsk-1e08ec4a130e2745d96df169e67c58df98a07311.tar.gz
KVM: optimize apic interrupt delivery
Most interrupt are delivered to only one vcpu. Use pre-build tables to find interrupt destination instead of looping through all vcpus. In case of logical mode loop only through vcpus in a logical cluster irq is sent to. Signed-off-by: Gleb Natapov <gleb@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
-rw-r--r--arch/x86/include/asm/kvm_host.h12
-rw-r--r--arch/x86/kvm/lapic.c188
-rw-r--r--arch/x86/kvm/lapic.h3
-rw-r--r--arch/x86/kvm/x86.c2
-rw-r--r--virt/kvm/irq_comm.c7
5 files changed, 199 insertions, 13 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 43aeb942283..0b902c98f27 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -525,6 +525,16 @@ struct kvm_arch_memory_slot {
struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];
};
+struct kvm_apic_map {
+ struct rcu_head rcu;
+ 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];
+};
+
struct kvm_arch {
unsigned int n_used_mmu_pages;
unsigned int n_requested_mmu_pages;
@@ -542,6 +552,8 @@ struct kvm_arch {
struct kvm_ioapic *vioapic;
struct kvm_pit *vpit;
int vapics_in_nmi_mode;
+ struct mutex apic_map_lock;
+ struct kvm_apic_map *apic_map;
unsigned int tss_addr;
struct page *apic_access_page;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6f9fd633c88..c6e6b721b6e 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -140,11 +140,110 @@ static inline int apic_enabled(struct kvm_lapic *apic)
(LVT_MASK | APIC_MODE_MASK | APIC_INPUT_POLARITY | \
APIC_LVT_REMOTE_IRR | APIC_LVT_LEVEL_TRIGGER)
+static inline int apic_x2apic_mode(struct kvm_lapic *apic)
+{
+ return apic->vcpu->arch.apic_base & X2APIC_ENABLE;
+}
+
static inline int kvm_apic_id(struct kvm_lapic *apic)
{
return (kvm_apic_get_reg(apic, APIC_ID) >> 24) & 0xff;
}
+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;
+
+ BUG_ON(cid >= ARRAY_SIZE(map->logical_map));
+
+ 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 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);
+
+ mutex_lock(&kvm->arch.apic_map_lock);
+
+ 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;
+ u16 cid, lid;
+ u32 ldr;
+
+ if (!kvm_apic_present(vcpu))
+ continue;
+
+ /*
+ * 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 xapic/flat 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 (apic_x2apic_mode(apic)) {
+ new->ldr_bits = 32;
+ new->cid_shift = 16;
+ new->cid_mask = new->lid_mask = 0xffff;
+ } else if (kvm_apic_sw_enabled(apic) &&
+ !new->cid_mask /* flat mode */ &&
+ kvm_apic_get_reg(apic, APIC_DFR) == APIC_DFR_CLUSTER) {
+ new->cid_shift = 4;
+ new->cid_mask = 0xf;
+ new->lid_mask = 0xf;
+ }
+
+ new->phys_map[kvm_apic_id(apic)] = apic;
+
+ ldr = kvm_apic_get_reg(apic, APIC_LDR);
+ cid = apic_cluster_id(new, ldr);
+ lid = apic_logical_id(new, ldr);
+
+ if (lid)
+ new->logical_map[cid][ffs(lid) - 1] = apic;
+ }
+out:
+ old = rcu_dereference_protected(kvm->arch.apic_map,
+ lockdep_is_held(&kvm->arch.apic_map_lock));
+ rcu_assign_pointer(kvm->arch.apic_map, new);
+ mutex_unlock(&kvm->arch.apic_map_lock);
+
+ if (old)
+ kfree_rcu(old, rcu);
+}
+
+static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
+{
+ apic_set_reg(apic, APIC_ID, id << 24);
+ recalculate_apic_map(apic->vcpu->kvm);
+}
+
+static inline void kvm_apic_set_ldr(struct kvm_lapic *apic, u32 id)
+{
+ apic_set_reg(apic, APIC_LDR, id);
+ recalculate_apic_map(apic->vcpu->kvm);
+}
+
static inline int apic_lvt_enabled(struct kvm_lapic *apic, int lvt_type)
{
return !(kvm_apic_get_reg(apic, lvt_type) & APIC_LVT_MASKED);
@@ -194,11 +293,6 @@ void kvm_apic_set_version(struct kvm_vcpu *vcpu)
apic_set_reg(apic, APIC_LVR, v);
}
-static inline int apic_x2apic_mode(struct kvm_lapic *apic)
-{
- return apic->vcpu->arch.apic_base & X2APIC_ENABLE;
-}
-
static const unsigned int apic_lvt_mask[APIC_LVT_NUM] = {
LVT_MASK , /* part LVTT mask, timer mode mask added at runtime */
LVT_MASK | APIC_MODE_MASK, /* LVTTHMR */
@@ -483,6 +577,72 @@ int kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
return result;
}
+bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
+ struct kvm_lapic_irq *irq, int *r)
+{
+ struct kvm_apic_map *map;
+ unsigned long bitmap = 1;
+ struct kvm_lapic **dst;
+ int i;
+ bool ret = false;
+
+ *r = -1;
+
+ if (irq->shorthand == APIC_DEST_SELF) {
+ *r = kvm_apic_set_irq(src->vcpu, irq);
+ return true;
+ }
+
+ if (irq->shorthand)
+ return false;
+
+ rcu_read_lock();
+ map = rcu_dereference(kvm->arch.apic_map);
+
+ if (!map)
+ goto out;
+
+ if (irq->dest_mode == 0) { /* physical mode */
+ if (irq->delivery_mode == APIC_DM_LOWEST ||
+ irq->dest_id == 0xff)
+ goto out;
+ dst = &map->phys_map[irq->dest_id & 0xff];
+ } else {
+ u32 mda = irq->dest_id << (32 - map->ldr_bits);
+
+ dst = map->logical_map[apic_cluster_id(map, mda)];
+
+ bitmap = apic_logical_id(map, mda);
+
+ if (irq->delivery_mode == APIC_DM_LOWEST) {
+ 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)
+ l = i;
+ }
+
+ bitmap = (l >= 0) ? 1 << l : 0;
+ }
+ }
+
+ for_each_set_bit(i, &bitmap, 16) {
+ if (!dst[i])
+ continue;
+ if (*r < 0)
+ *r = 0;
+ *r += kvm_apic_set_irq(dst[i]->vcpu, irq);
+ }
+
+ ret = true;
+out:
+ rcu_read_unlock();
+ return ret;
+}
+
/*
* Add a pending IRQ into lapic.
* Return 1 if successfully added and 0 if discarded.
@@ -886,7 +1046,7 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
switch (reg) {
case APIC_ID: /* Local APIC ID */
if (!apic_x2apic_mode(apic))
- apic_set_reg(apic, APIC_ID, val);
+ kvm_apic_set_id(apic, val >> 24);
else
ret = 1;
break;
@@ -902,15 +1062,16 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
case APIC_LDR:
if (!apic_x2apic_mode(apic))
- apic_set_reg(apic, APIC_LDR, val & APIC_LDR_MASK);
+ kvm_apic_set_ldr(apic, val & APIC_LDR_MASK);
else
ret = 1;
break;
case APIC_DFR:
- if (!apic_x2apic_mode(apic))
+ if (!apic_x2apic_mode(apic)) {
apic_set_reg(apic, APIC_DFR, val | 0x0FFFFFFF);
- else
+ recalculate_apic_map(apic->vcpu->kvm);
+ } else
ret = 1;
break;
@@ -1141,6 +1302,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
static_key_slow_dec_deferred(&apic_hw_disabled);
else
static_key_slow_inc(&apic_hw_disabled.key);
+ recalculate_apic_map(vcpu->kvm);
}
if (!kvm_vcpu_is_bsp(apic->vcpu))
@@ -1150,7 +1312,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
if (apic_x2apic_mode(apic)) {
u32 id = kvm_apic_id(apic);
u32 ldr = ((id & ~0xf) << 16) | (1 << (id & 0xf));
- apic_set_reg(apic, APIC_LDR, ldr);
+ kvm_apic_set_ldr(apic, ldr);
}
apic->base_address = apic->vcpu->arch.apic_base &
MSR_IA32_APICBASE_BASE;
@@ -1175,7 +1337,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu)
/* Stop the timer in case it's a reset to an active apic */
hrtimer_cancel(&apic->lapic_timer.timer);
- apic_set_reg(apic, APIC_ID, vcpu->vcpu_id << 24);
+ kvm_apic_set_id(apic, vcpu->vcpu_id);
kvm_apic_set_version(apic->vcpu);
for (i = 0; i < APIC_LVT_NUM; i++)
@@ -1186,7 +1348,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu)
apic_set_reg(apic, APIC_DFR, 0xffffffffU);
apic_set_spiv(apic, 0xff);
apic_set_reg(apic, APIC_TASKPRI, 0);
- apic_set_reg(apic, APIC_LDR, 0);
+ kvm_apic_set_ldr(apic, 0);
apic_set_reg(apic, APIC_ESR, 0);
apic_set_reg(apic, APIC_ICR, 0);
apic_set_reg(apic, APIC_ICR2, 0);
@@ -1404,6 +1566,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
/* set SPIV separately to get count of SW disabled APICs right */
apic_set_spiv(apic, *((u32 *)(s->regs + APIC_SPIV)));
memcpy(vcpu->arch.apic->regs, s->regs, sizeof *s);
+ /* call kvm_apic_set_id() to put apic into apic_map */
+ kvm_apic_set_id(apic, kvm_apic_id(apic));
kvm_apic_set_version(vcpu);
apic_update_ppr(apic);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 615a8b03016..e5ebf9f3571 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -52,6 +52,9 @@ int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda);
int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq);
int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
+bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
+ struct kvm_lapic_irq *irq, int *r);
+
u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
void kvm_set_apic_base(struct kvm_vcpu *vcpu, u64 data);
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 497226e49d4..fc2a0a132e4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6270,6 +6270,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);
raw_spin_lock_init(&kvm->arch.tsc_write_lock);
+ mutex_init(&kvm->arch.apic_map_lock);
return 0;
}
@@ -6322,6 +6323,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
put_page(kvm->arch.apic_access_page);
if (kvm->arch.ept_identity_pagetable)
put_page(kvm->arch.ept_identity_pagetable);
+ kfree(rcu_dereference_check(kvm->arch.apic_map, 1));
}
void kvm_arch_free_memslot(struct kvm_memory_slot *free,
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 7118be0f2f2..3ca89c451d6 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -68,8 +68,13 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
struct kvm_vcpu *vcpu, *lowest = NULL;
if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
- kvm_is_dm_lowest_prio(irq))
+ kvm_is_dm_lowest_prio(irq)) {
printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
+ irq->delivery_mode = APIC_DM_FIXED;
+ }
+
+ if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r))
+ return r;
kvm_for_each_vcpu(i, vcpu, kvm) {
if (!kvm_apic_present(vcpu))