On Tue, Sep 11, 2012 at 04:02:25PM +0300, Gleb Natapov wrote: > 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@xxxxxxxxxx> Added Paul just to make sure we are using RCU correctly. Paul could you pls answer the question below? > --- > Changelog: > > - v1->v2 > * fix race Avi noticed > * rcu_read_lock() out of the block as per Avi > * fix rcu issues pointed to by MST. All but one. Still use > call_rcu(). Do not think this is serious issue. If it is should be > solved by RCU subsystem. > * Fix phys_map overflow pointed to by MST > * recalculate_apic_map() does not return error any more. > * add optimization for low prio logical mode with one cpu as dst (it > happens) > > I did not rewrote kvm_irq_delivery_to_apic_fast() MST way since my way > looks cleaner to me. > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 64adb61..3ba8951 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -511,6 +511,14 @@ struct kvm_arch_memory_slot { > struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1]; > }; > > +struct kvm_apic_map { > + struct rcu_head rcu; > + bool flat; > + u8 ldr_bits; > + struct kvm_lapic *phys_map[256]; > + struct kvm_lapic *logical_map[16][16]; > +}; > + > struct kvm_arch { > unsigned int n_used_mmu_pages; > unsigned int n_requested_mmu_pages; > @@ -528,6 +536,8 @@ struct kvm_arch { > struct kvm_ioapic *vioapic; > struct kvm_pit *vpit; > int vapics_in_nmi_mode; > + struct kvm_apic_map *apic_map; > + struct mutex apic_map_lock; > > unsigned int tss_addr; > struct page *apic_access_page; > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 07ad628..06672e8 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -139,11 +139,92 @@ 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 void kvm_apic_get_logical_id(u32 ldr, bool flat, u8 ldr_bits, > + u16 *cid, u16 *lid) > +{ > + if (ldr_bits == 32) { > + *cid = ldr >> 16; > + *lid = ldr & 0xffff; > + } else { > + ldr = GET_APIC_LOGICAL_ID(ldr); > + > + if (flat) { > + *cid = 0; > + *lid = ldr; > + } else { > + *cid = ldr >> 4; > + *lid = ldr & 0xf; > + } > + } > +} > + > +static inline 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; > + new->flat = true; > + kvm_for_each_vcpu(i, vcpu, kvm) { > + u16 cid, lid; > + struct kvm_lapic *apic = vcpu->arch.apic; > + > + if (!kvm_apic_present(vcpu)) > + continue; > + > + if (apic_x2apic_mode(apic)) { > + new->ldr_bits = 32; > + new->flat = false; > + } else if (kvm_apic_sw_enabled(apic) && new->flat && > + kvm_apic_get_reg(apic, APIC_DFR) == APIC_DFR_CLUSTER) > + new->flat = false; > + > + new->phys_map[kvm_apic_id(apic)] = apic; > + kvm_apic_get_logical_id(kvm_apic_get_reg(apic, APIC_LDR), > + new->flat, new->ldr_bits, &cid, &lid); > + > + if (lid) > + new->logical_map[cid][ffs(lid) - 1] = apic; > + } > +out: > + old = kvm->arch.apic_map; > + rcu_assign_pointer(kvm->arch.apic_map, new); > + mutex_unlock(&kvm->arch.apic_map_lock); > + > + if (old) > + kfree_rcu(old, rcu); > +} Paul, I'd like to check something with you here: this function can be triggered by userspace, any number of times; we allocate a 2K chunk of memory that is later freed by kfree_rcu. Is there a risk of DOS if RCU is delayed while lots of memory is queued up in this way? If yes is this a generic problem with kfree_rcu that should be addressed in core kernel? Thanks! > + > +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); > @@ -193,11 +274,6 @@ 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 */ > @@ -477,6 +553,79 @@ 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; > + > + *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) { > + rcu_read_unlock(); > + return false; > + } > + > + if (irq->dest_mode == 0) { /* physical mode */ > + if (irq->delivery_mode == APIC_DM_LOWEST || > + irq->dest_id == 0xff) { > + rcu_read_unlock(); > + return false; > + } > + dst = &map->phys_map[irq->dest_id & 0xff]; > + } else { > + u16 cid, lid; > + u32 mda = irq->dest_id; > + > + if (map->ldr_bits == 8) > + mda <<= 24; > + > + kvm_apic_get_logical_id(mda, map->flat, map->ldr_bits, > + &cid, &lid); > + dst = map->logical_map[cid]; > + > + bitmap = lid; > + if (irq->delivery_mode == APIC_DM_LOWEST && > + hweight_long(bitmap) > 1) { > + 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); > + } > + > + rcu_read_unlock(); > + return true; > +} > + > /* > * Add a pending IRQ into lapic. > * Return 1 if successfully added and 0 if discarded. > @@ -880,7 +1029,7 @@ 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; > @@ -896,15 +1045,16 @@ 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; > > @@ -1135,6 +1285,7 @@ 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)) > @@ -1144,7 +1295,7 @@ 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; > @@ -1169,7 +1320,7 @@ 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, (u8)vcpu->vcpu_id); > kvm_apic_set_version(apic->vcpu); > > for (i = 0; i < APIC_LVT_NUM; i++) > @@ -1180,7 +1331,7 @@ 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); > @@ -1398,6 +1549,8 @@ 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 615a8b0..e5ebf9f 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 f91e2c9..db6db8f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6269,6 +6269,7 @@ 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; > } > @@ -6319,6 +6320,7 @@ 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(kvm->arch.apic_map); > } > > 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 7118be0..3ca89c4 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)) > -- > Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html