From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752197AbcGAH61 (ORCPT ); Fri, 1 Jul 2016 03:58:27 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:32867 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915AbcGAH6Y (ORCPT ); Fri, 1 Jul 2016 03:58:24 -0400 Subject: Re: [PATCH v1 02/11] KVM: x86: add kvm_apic_map_get_dest_lapic To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <20160630205429.16480-1-rkrcmar@redhat.com> <20160630205429.16480-3-rkrcmar@redhat.com> Cc: "Lan, Tianyu" , Igor Mammedov , Jan Kiszka , Peter Xu From: Paolo Bonzini Message-ID: <7f5a8277-f905-e6a2-fba8-7f859d300b66@redhat.com> Date: Fri, 1 Jul 2016 09:57:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <20160630205429.16480-3-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/06/2016 22:54, Radim Krčmář wrote: > kvm_irq_delivery_to_apic_fast and kvm_intr_is_single_vcpu_fast both > compute the interrupt destination. Factor the code. > > 'struct kvm_lapic **dst = NULL' had to be added to silence GCC. > GCC might complain about potential NULL access in the future, because it > missed conditions that avoided uninitialized uses of dst. > > Signed-off-by: Radim Krčmář > --- > v1: improved comment for kvm_apic_map_get_dest_lapic() [Peter] > > arch/x86/kvm/lapic.c | 241 ++++++++++++++++++++++----------------------------- > 1 file changed, 103 insertions(+), 138 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 22a6474af220..238b87b068db 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -671,14 +671,98 @@ static void kvm_apic_disabled_lapic_found(struct kvm *kvm) > } > } > > +/* Return true if the interrupt can be handled by using *bitmap as index mask > + * for valid destinations in *dst array. > + * Return false if kvm_apic_map_get_dest_lapic did nothing useful. > + * Note: we may have zero kvm_lapic destinations when we return true, which > + * means that the interrupt should be dropped. In this case, *bitmap would be > + * zero and *dst undefined. > + */ > +static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, struct kvm_lapic *src, > + struct kvm_lapic_irq *irq, struct kvm_apic_map *map, > + struct kvm_lapic ***dst, unsigned long *bitmap) > +{ > + int i, lowest; > + bool x2apic_ipi; > + u16 cid; > + > + if (irq->shorthand == APIC_DEST_SELF) { > + *dst = &src; This is not valid, &src dies as soon as you leave the function. You need to pass &src into kvm_apic_map_get_dest_lapic and here do something like if (irq->shorthand) { if (irq->shorthand == APIC_DEST_SELF && p_src) { *dst = p_src; *bitmap = 1; return true; } return false; } If it's not too hard, I'd like to have patch 4 before this one. Paolo > + *bitmap = 1; > + return true; > + } else if (irq->shorthand) > + return false; > + > + x2apic_ipi = src && apic_x2apic_mode(src); > + if (irq->dest_id == (x2apic_ipi ? X2APIC_BROADCAST : APIC_BROADCAST)) > + return false; > + > + if (!map) > + return false; > + > + if (irq->dest_mode == APIC_DEST_PHYSICAL) { > + if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) { > + *bitmap = 0; > + } else { > + *dst = &map->phys_map[irq->dest_id]; > + *bitmap = 1; > + } > + return true; > + } > + > + if (!kvm_apic_logical_map_valid(map)) > + return false; > + > + apic_logical_id(map, irq->dest_id, &cid, (u16 *)bitmap); > + > + if (cid >= ARRAY_SIZE(map->logical_map)) { > + *bitmap = 0; > + return true; > + } > + > + *dst = map->logical_map[cid]; > + > + if (!kvm_lowest_prio_delivery(irq)) > + return true; > + > + if (!kvm_vector_hashing_enabled()) { > + lowest = -1; > + for_each_set_bit(i, bitmap, 16) { > + if (!(*dst)[i]) > + continue; > + if (lowest < 0) > + lowest = i; > + else if (kvm_apic_compare_prio((*dst)[i]->vcpu, > + (*dst)[lowest]->vcpu) < 0) > + lowest = i; > + } > + } else { > + if (!*bitmap) > + return true; > + > + lowest = kvm_vector_to_index(irq->vector, hweight16(*bitmap), > + bitmap, 16); > + > + if (!(*dst)[lowest]) { > + kvm_apic_disabled_lapic_found(kvm); > + *bitmap = 0; > + return true; > + } > + } > + > + *bitmap = (lowest >= 0) ? 1 << lowest : 0; > + > + return true; > +} > + > bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, > struct kvm_lapic_irq *irq, int *r, struct dest_map *dest_map) > { > struct kvm_apic_map *map; > - unsigned long bitmap = 1; > - struct kvm_lapic **dst; > + unsigned long bitmap; > + struct kvm_lapic **dst = NULL; > int i; > - bool ret, x2apic_ipi; > + bool ret; > > *r = -1; > > @@ -687,86 +771,19 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, > return true; > } > > - if (irq->shorthand) > - return false; > - > - x2apic_ipi = src && apic_x2apic_mode(src); > - if (irq->dest_id == (x2apic_ipi ? X2APIC_BROADCAST : APIC_BROADCAST)) > - return false; > - > - ret = true; > rcu_read_lock(); > map = rcu_dereference(kvm->arch.apic_map); > > - if (!map) { > - ret = false; > - goto out; > - } > - > - if (irq->dest_mode == APIC_DEST_PHYSICAL) { > - if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) > - goto out; > - > - dst = &map->phys_map[irq->dest_id]; > - } else { > - u16 cid; > - > - if (!kvm_apic_logical_map_valid(map)) { > - ret = false; > - goto out; > + ret = kvm_apic_map_get_dest_lapic(kvm, src, irq, map, &dst, &bitmap); > + if (ret) > + 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, dest_map); > } > > - apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap); > - > - if (cid >= ARRAY_SIZE(map->logical_map)) > - goto out; > - > - dst = map->logical_map[cid]; > - > - if (!kvm_lowest_prio_delivery(irq)) > - goto set_irq; > - > - if (!kvm_vector_hashing_enabled()) { > - 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; > - } else { > - int idx; > - unsigned int dest_vcpus; > - > - dest_vcpus = hweight16(bitmap); > - if (dest_vcpus == 0) > - goto out; > - > - idx = kvm_vector_to_index(irq->vector, > - dest_vcpus, &bitmap, 16); > - > - if (!dst[idx]) { > - kvm_apic_disabled_lapic_found(kvm); > - goto out; > - } > - > - bitmap = (idx >= 0) ? 1 << idx : 0; > - } > - } > - > -set_irq: > - 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, dest_map); > - } > -out: > rcu_read_unlock(); > return ret; > } > @@ -789,8 +806,9 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, > struct kvm_vcpu **dest_vcpu) > { > struct kvm_apic_map *map; > + unsigned long bitmap; > + struct kvm_lapic **dst = NULL; > bool ret = false; > - struct kvm_lapic *dst = NULL; > > if (irq->shorthand) > return false; > @@ -798,69 +816,16 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, > rcu_read_lock(); > map = rcu_dereference(kvm->arch.apic_map); > > - if (!map) > - goto out; > + if (kvm_apic_map_get_dest_lapic(kvm, NULL, irq, map, &dst, &bitmap) && > + hweight16(bitmap) == 1) { > + unsigned long i = find_first_bit(&bitmap, 16); > > - if (irq->dest_mode == APIC_DEST_PHYSICAL) { > - if (irq->dest_id == 0xFF) > - goto out; > - > - if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) > - goto out; > - > - dst = map->phys_map[irq->dest_id]; > - if (dst && kvm_apic_present(dst->vcpu)) > - *dest_vcpu = dst->vcpu; > - else > - goto out; > - } else { > - u16 cid; > - unsigned long bitmap = 1; > - int i, r = 0; > - > - if (!kvm_apic_logical_map_valid(map)) > - goto out; > - > - apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap); > - > - if (cid >= ARRAY_SIZE(map->logical_map)) > - goto out; > - > - if (kvm_vector_hashing_enabled() && > - kvm_lowest_prio_delivery(irq)) { > - int idx; > - unsigned int dest_vcpus; > - > - dest_vcpus = hweight16(bitmap); > - if (dest_vcpus == 0) > - goto out; > - > - idx = kvm_vector_to_index(irq->vector, dest_vcpus, > - &bitmap, 16); > - > - dst = map->logical_map[cid][idx]; > - if (!dst) { > - kvm_apic_disabled_lapic_found(kvm); > - goto out; > - } > - > - *dest_vcpu = dst->vcpu; > - } else { > - for_each_set_bit(i, &bitmap, 16) { > - dst = map->logical_map[cid][i]; > - if (++r == 2) > - goto out; > - } > - > - if (dst && kvm_apic_present(dst->vcpu)) > - *dest_vcpu = dst->vcpu; > - else > - goto out; > + if (dst[i]) { > + *dest_vcpu = dst[i]->vcpu; > + ret = true; > } > } > > - ret = true; > -out: > rcu_read_unlock(); > return ret; > } >