From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754089Ab2GRVv4 (ORCPT ); Wed, 18 Jul 2012 17:51:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39343 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751434Ab2GRVvy (ORCPT ); Wed, 18 Jul 2012 17:51:54 -0400 Date: Thu, 19 Jul 2012 00:52:28 +0300 From: "Michael S. Tsirkin" To: Avi Kivity , Marcelo Tosatti , Alex Williamson , gleb@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] kvm: fix race with level interrupts Message-ID: <20120718215228.GA13905@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When more than 1 source id is in use for the same GSI, we have the following race related to handling irq_states: CPU 0 clears bit in irq_states. CPU 0 reads irq_state as 0. CPU 1 sets bit in irq_states. CPU 1 calls kvm_ioapic_set_irq(1). CPU 0 calls kvm_ioapic_set_irq(0). Now ioapic thinks the level is 0 but irq_state is not 0. Note that above is valid behaviour if CPU0 and CPU1 are using different source ids. Fix by performing all irq_states bitmap handling under pic/ioapic lock. This also removes the need for atomics with irq_states handling. Reported-by: Gleb Natapov Signed-off-by: Michael S. Tsirkin --- This survives stress testing for me (though I only tried virtio, not device assignment). Avi, Marcelo, though we have not observed this in the field, it's a bugfix so probably 3.5 material? I assume yes so the patch is against 3.5-rc7. Also stable? It's a very old bug. arch/x86/include/asm/kvm_host.h | 15 ++++++++++++++- arch/x86/kvm/i8259.c | 14 ++++++++++++-- virt/kvm/ioapic.c | 13 ++++++++++++- virt/kvm/ioapic.h | 4 +++- virt/kvm/irq_comm.c | 31 ++++--------------------------- 5 files changed, 45 insertions(+), 32 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index db7c1f2..fe6e9f1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -802,7 +802,20 @@ int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); -int kvm_pic_set_irq(void *opaque, int irq, int level); +static inline int kvm_irq_line_state(unsigned long *irq_state, + int irq_source_id, int level) +{ + /* Logical OR for level trig interrupt */ + if (level) + __set_bit(irq_source_id, irq_state); + else + __clear_bit(irq_source_id, irq_state); + + return !!(*irq_state); +} + +int kvm_pic_set_irq(struct kvm_pic *pic, int irq, int irq_source_id, int level); +void kvm_pic_clear_all(struct kvm_pic *pic, int irq_source_id); void kvm_inject_nmi(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c index 81cf4fa..95b504b 100644 --- a/arch/x86/kvm/i8259.c +++ b/arch/x86/kvm/i8259.c @@ -188,13 +188,14 @@ void kvm_pic_update_irq(struct kvm_pic *s) pic_unlock(s); } -int kvm_pic_set_irq(void *opaque, int irq, int level) +int kvm_pic_set_irq(struct kvm_pic *s, int irq, int src_id, int l) { - struct kvm_pic *s = opaque; int ret = -1; + int level; pic_lock(s); if (irq >= 0 && irq < PIC_NUM_PINS) { + level = kvm_irq_line_state(&s->irq_states[irq], src_id, l); ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, level); pic_update_irq(s); trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr, @@ -205,6 +206,15 @@ int kvm_pic_set_irq(void *opaque, int irq, int level) return ret; } +void kvm_pic_clear_all(struct kvm_pic *s, int src_id) +{ + int i; + pic_lock(s); + for (i = 0; i < PIC_NUM_PINS; i++) + __clear_bit(src_id, &s->irq_states[i]); + pic_unlock(s); +} + /* * acknowledge interrupt 'irq' */ diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 26fd54d..268b332 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -191,17 +191,19 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq) return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe); } -int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) +int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int src_id, int l) { u32 old_irr; u32 mask = 1 << irq; union kvm_ioapic_redirect_entry entry; int ret = 1; + int level; spin_lock(&ioapic->lock); old_irr = ioapic->irr; if (irq >= 0 && irq < IOAPIC_NUM_PINS) { entry = ioapic->redirtbl[irq]; + level = kvm_irq_line_state(&ioapic->irq_states[irq], src_id, l); level ^= entry.fields.polarity; if (!level) ioapic->irr &= ~mask; @@ -221,6 +223,15 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) return ret; } +void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int src_id) +{ + int i; + spin_lock(&ioapic->lock); + for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) + __clear_bit(src_id, &ioapic->irq_states[i]); + spin_unlock(&ioapic->lock); +} + static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector, int trigger_mode) { diff --git a/virt/kvm/ioapic.h b/virt/kvm/ioapic.h index 32872a0..a30abfe 100644 --- a/virt/kvm/ioapic.h +++ b/virt/kvm/ioapic.h @@ -74,7 +74,9 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode); bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector); int kvm_ioapic_init(struct kvm *kvm); void kvm_ioapic_destroy(struct kvm *kvm); -int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level); +int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id, + int level); +void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int irq_source_id); void kvm_ioapic_reset(struct kvm_ioapic *ioapic); int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, struct kvm_lapic_irq *irq); diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c index 5afb431..83402d7 100644 --- a/virt/kvm/irq_comm.c +++ b/virt/kvm/irq_comm.c @@ -33,26 +33,12 @@ #include "ioapic.h" -static inline int kvm_irq_line_state(unsigned long *irq_state, - int irq_source_id, int level) -{ - /* Logical OR for level trig interrupt */ - if (level) - set_bit(irq_source_id, irq_state); - else - clear_bit(irq_source_id, irq_state); - - return !!(*irq_state); -} - static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm, int irq_source_id, int level) { #ifdef CONFIG_X86 struct kvm_pic *pic = pic_irqchip(kvm); - level = kvm_irq_line_state(&pic->irq_states[e->irqchip.pin], - irq_source_id, level); - return kvm_pic_set_irq(pic, e->irqchip.pin, level); + return kvm_pic_set_irq(pic, e->irqchip.pin, irq_source_id, level); #else return -1; #endif @@ -62,10 +48,7 @@ static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm, int irq_source_id, int level) { struct kvm_ioapic *ioapic = kvm->arch.vioapic; - level = kvm_irq_line_state(&ioapic->irq_states[e->irqchip.pin], - irq_source_id, level); - - return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, level); + return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, irq_source_id, level); } inline static bool kvm_is_dm_lowest_prio(struct kvm_lapic_irq *irq) @@ -249,8 +232,6 @@ unlock: void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id) { - int i; - ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID); mutex_lock(&kvm->irq_lock); @@ -263,14 +244,10 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id) if (!irqchip_in_kernel(kvm)) goto unlock; - for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) { - clear_bit(irq_source_id, &kvm->arch.vioapic->irq_states[i]); - if (i >= 16) - continue; + kvm_ioapic_clear_all(kvm->arch.vioapic, irq_source_id); #ifdef CONFIG_X86 - clear_bit(irq_source_id, &pic_irqchip(kvm)->irq_states[i]); + kvm_pic_clear_all(pic_irqchip(kvm), irq_source_id); #endif - } unlock: mutex_unlock(&kvm->irq_lock); } -- MST