| Message ID | 20160712200930.32143-5-rkrcmar@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 12/07/2016 22:09, Radim Krčmář wrote: > x2APIC supports up to 2^32-1 LAPICs, but most guest in coming years will > have slighly less VCPUs. It's "fewer", not "less" (that's important to make the joke less uncanny for native speakers :)). Less goes with uncountable nouns such as milk. Paolo > Dynamic size saves memory at the cost of > turning one constant into a variable. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-07-13 10:29+0200, Paolo Bonzini: > On 12/07/2016 22:09, Radim Krčmář wrote: >> x2APIC supports up to 2^32-1 LAPICs, but most guest in coming years will >> have slighly less VCPUs. > > It's "fewer", not "less" (that's important to make the joke less uncanny > for native speakers :)). Less goes with uncountable nouns such as milk. Thanks. My syntax should be enough to creep native speakers. :) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-07-13 4:09 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: [...] > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 9880d03f533d..224fc1c5fcc6 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -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; If this should be max_id = KVM_MAX_VCPU_ID? I have a patch on hand to fix it, but I didn't know whether it is your desired behavior or not. Regards, Wanpeng Li -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-08-02 19:39+0800, Wanpeng Li: > 2016-07-13 4:09 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: > [...] >> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c >> @@ -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; > > If this should be max_id = KVM_MAX_VCPU_ID? I have a patch on hand to > fix it, but I didn't know whether it is your desired behavior or not. No, we could just have static array then. KVM_MAX_VCPU_ID is expected to be raised to INT_MAX and eventually UINT_MAX, so it would not be practical. The dynamic array is there to avoid wasting space in the common case, where VMs have only low APIC IDs. Inintial patches had 255 to minimize a chance of regressions as the static array was that big, but starting with max_id = 0 is our goal and should be ok even without other changes. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-08-02 20:22 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: > 2016-08-02 19:39+0800, Wanpeng Li: >> 2016-07-13 4:09 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: >> [...] >>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c >>> @@ -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; >> >> If this should be max_id = KVM_MAX_VCPU_ID? I have a patch on hand to >> fix it, but I didn't know whether it is your desired behavior or not. > > No, we could just have static array then. KVM_MAX_VCPU_ID is expected > to be raised to INT_MAX and eventually UINT_MAX, so it would not be > practical. The dynamic array is there to avoid wasting space in the > common case, where VMs have only low APIC IDs. > > Inintial patches had 255 to minimize a chance of regressions as the > static array was that big, but starting with max_id = 0 is our goal and > should be ok even without other changes. I see, thanks. :) Regards, Wanpeng Li -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 3194b19b9c7b..643e3dffcd85 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -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 */ diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 9880d03f533d..224fc1c5fcc6 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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]; diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 336ba51bb16e..8d811139d2b3 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -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; }
x2APIC supports up to 2^32-1 LAPICs, but most guest in coming years will have slighly less 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: Radim Krčmář <rkrcmar@redhat.com> --- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/lapic.c | 18 +++++++++++++----- arch/x86/kvm/lapic.h | 2 +- 3 files changed, 16 insertions(+), 7 deletions(-)