From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752193AbdHHNIY (ORCPT ); Tue, 8 Aug 2017 09:08:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33714 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751880AbdHHNIW (ORCPT ); Tue, 8 Aug 2017 09:08:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 88E406148D Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=pbonzini@redhat.com Subject: Re: [PATCH] KVM: X86: expand ->arch.apic_arb_prio to u64 To: "Longpeng(Mike)" , rkrcmar@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, weidong.huang@huawei.com, arei.gonglei@huawei.com, wangxinxin.wang@huawei.com, longpeng.mike@gmail.com References: <1502192234-14068-1-git-send-email-longpeng2@huawei.com> From: Paolo Bonzini Message-ID: <5e5d4edc-5861-b3d9-b4a2-890c9bbd53e0@redhat.com> Date: Tue, 8 Aug 2017 15:08:17 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1502192234-14068-1-git-send-email-longpeng2@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 08 Aug 2017 13:08:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/08/2017 13:37, Longpeng(Mike) wrote: > Currently 'apic_arb_prio' is int32_t, it's too short for long > time running. In our environment, it overflowed and then the > UBSAN was angry: > > signed integer overflow: > 2147483647 + 1 cannot be represented in type 'int' > CPU: 22 PID: 31237 Comm: qemu-kvm Tainted: ... > ... > Call Trace: > [] dump_stack+0x1e/0x20 > [] ubsan_epilogue+0x12/0x55 > [] handle_overflow+0x1ba/0x215 > [] __ubsan_handle_add_overflow+0x2a/0x31 > [] __apic_accept_irq+0x57a/0x5d0 [kvm] > [] kvm_apic_set_irq+0x9f/0xf0 [kvm] > [] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm] > [] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm] > [] kvm_set_msi+0xa9/0x100 [kvm] > [] kvm_send_userspace_msi+0x14d/0x1f0 [kvm] > [] kvm_vm_ioctl+0x4ee/0xdd0 [kvm] > ... > > We expand it to u64, this is large enough. Suppose the vcpu receives > 1000 irqs per second, then it won't overflow in 584942417 years. > ( 18446744073709551615/1000/3600/24/365 = 584942417 ) Since you only look at the difference, changing it to uint32_t should be enough. Paolo > Signed-off-by: Longpeng(Mike) > --- > arch/x86/include/asm/kvm_host.h | 2 +- > arch/x86/kvm/ioapic.h | 3 ++- > arch/x86/kvm/irq_comm.c | 2 +- > arch/x86/kvm/lapic.c | 6 +++--- > 4 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 87ac4fb..ce9a5f5 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -499,7 +499,7 @@ struct kvm_vcpu_arch { > bool apicv_active; > DECLARE_BITMAP(ioapic_handled_vectors, 256); > unsigned long apic_attention; > - int32_t apic_arb_prio; > + u64 apic_arb_prio; > int mp_state; > u64 ia32_misc_enable_msr; > u64 smbase; > diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h > index 29ce197..a26deed 100644 > --- a/arch/x86/kvm/ioapic.h > +++ b/arch/x86/kvm/ioapic.h > @@ -117,7 +117,8 @@ static inline int ioapic_in_kernel(struct kvm *kvm) > void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu); > bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source, > int short_hand, unsigned int dest, int dest_mode); > -int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2); > +/* Return true if vcpu1's priority is lower */ > +bool kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2); > void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, > int trigger_mode); > int kvm_ioapic_init(struct kvm *kvm); > diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c > index 3cc3b2d..03b1487 100644 > --- a/arch/x86/kvm/irq_comm.c > +++ b/arch/x86/kvm/irq_comm.c > @@ -90,7 +90,7 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, > if (!kvm_vector_hashing_enabled()) { > if (!lowest) > lowest = vcpu; > - else if (kvm_apic_compare_prio(vcpu, lowest) < 0) > + else if (kvm_apic_compare_prio(vcpu, lowest)) > lowest = vcpu; > } else { > __set_bit(i, dest_vcpu_bitmap); > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 589dcc1..1e2b1f2 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -840,7 +840,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, > if (lowest < 0) > lowest = i; > else if (kvm_apic_compare_prio((*dst)[i]->vcpu, > - (*dst)[lowest]->vcpu) < 0) > + (*dst)[lowest]->vcpu)) > lowest = i; > } > } else { > @@ -1048,9 +1048,9 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, > return result; > } > > -int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2) > +bool kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2) > { > - return vcpu1->arch.apic_arb_prio - vcpu2->arch.apic_arb_prio; > + return vcpu1->arch.apic_arb_prio < vcpu2->arch.apic_arb_prio; > } > > static bool kvm_ioapic_handles_vector(struct kvm_lapic *apic, int vector) >