Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751805AbdHaKYq (ORCPT ); Thu, 31 Aug 2017 06:24:46 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:53834 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351AbdHaKYo (ORCPT ); Thu, 31 Aug 2017 06:24:44 -0400 Subject: Re: [PATCH v3 41/59] KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass To: Christoffer Dall Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Christoffer Dall , Thomas Gleixner , Jason Cooper , Eric Auger , Shanker Donthineni , Mark Rutland , Shameerali Kolothum Thodi References: <20170731172637.29355-1-marc.zyngier@arm.com> <20170731172637.29355-42-marc.zyngier@arm.com> <20170826194850.GB11074@cbox> <06930ddb-6c40-ff74-0062-cec236ce2455@arm.com> <20170830114646.GD24522@cbox> <9fc83ca2-bdae-ffbc-9d81-c77c331b47d2@arm.com> <20170830195930.GJ24522@cbox> From: Marc Zyngier Organization: ARM Ltd Message-ID: <5bc68ab5-5343-0cf2-f11b-9eb5936c7e60@arm.com> Date: Thu, 31 Aug 2017 11:24:37 +0100 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: <20170830195930.GJ24522@cbox> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11205 Lines: 291 On 30/08/17 20:59, Christoffer Dall wrote: > On Wed, Aug 30, 2017 at 01:53:30PM +0100, Marc Zyngier wrote: >> On 30/08/17 12:46, Christoffer Dall wrote: >>> On Wed, Aug 30, 2017 at 11:28:08AM +0100, Marc Zyngier wrote: >>>> On 26/08/17 20:48, Christoffer Dall wrote: >>>>> On Mon, Jul 31, 2017 at 06:26:19PM +0100, Marc Zyngier wrote: >>>>>> Let's use the irq bypass mechanism introduced for platform device >>>>>> interrupts to intercept the virtual PCIe endpoint configuration >>>>>> and establish our LPI->VLPI mapping. >>>>>> >>>>>> Signed-off-by: Marc Zyngier >>>>>> --- >>>>>> include/kvm/arm_vgic.h | 8 ++++ >>>>>> virt/kvm/arm/arm.c | 27 ++++++++---- >>>>>> virt/kvm/arm/vgic/vgic-v4.c | 103 ++++++++++++++++++++++++++++++++++++++++++++ >>>>>> 3 files changed, 130 insertions(+), 8 deletions(-) >>>>>> >>>>>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h >>>>>> index 359eeffe9857..050f78d4fb42 100644 >>>>>> --- a/include/kvm/arm_vgic.h >>>>>> +++ b/include/kvm/arm_vgic.h >>>>>> @@ -367,4 +367,12 @@ int kvm_vgic_set_forwarding(struct kvm *kvm, unsigned int host_irq, >>>>>> void kvm_vgic_unset_forwarding(struct kvm *kvm, unsigned int host_irq, >>>>>> unsigned int vintid); >>>>>> >>>>>> +struct kvm_kernel_irq_routing_entry; >>>>>> + >>>>>> +int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq, >>>>>> + struct kvm_kernel_irq_routing_entry *irq_entry); >>>>>> + >>>>>> +int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq, >>>>>> + struct kvm_kernel_irq_routing_entry *irq_entry); >>>>>> + >>>>>> #endif /* __KVM_ARM_VGIC_H */ >>>>>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c >>>>>> index ebab6c29e3be..6803ea27c47d 100644 >>>>>> --- a/virt/kvm/arm/arm.c >>>>>> +++ b/virt/kvm/arm/arm.c >>>>>> @@ -1457,11 +1457,16 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, >>>>>> struct kvm_kernel_irqfd *irqfd = >>>>>> container_of(cons, struct kvm_kernel_irqfd, consumer); >>>>>> >>>>>> - if (prod->type != IRQ_BYPASS_VFIO_PLATFORM) >>>>>> + switch (prod->type) { >>>>>> + case IRQ_BYPASS_VFIO_PLATFORM: >>>>>> + return kvm_vgic_set_forwarding(irqfd->kvm, prod->irq, >>>>>> + irqfd->gsi + VGIC_NR_PRIVATE_IRQS); >>>>>> + case IRQ_BYPASS_VFIO_PCI_MSI: >>>>>> + return kvm_vgic_v4_set_forwarding(irqfd->kvm, prod->irq, >>>>>> + &irqfd->irq_entry); >>>>>> + default: >>>>>> return 0; >>>>>> - >>>>>> - return kvm_vgic_set_forwarding(irqfd->kvm, prod->irq, >>>>>> - irqfd->gsi + VGIC_NR_PRIVATE_IRQS); >>>>>> + } >>>>>> } >>>>>> void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons, >>>>>> struct irq_bypass_producer *prod) >>>>>> @@ -1469,11 +1474,17 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons, >>>>>> struct kvm_kernel_irqfd *irqfd = >>>>>> container_of(cons, struct kvm_kernel_irqfd, consumer); >>>>>> >>>>>> - if (prod->type != IRQ_BYPASS_VFIO_PLATFORM) >>>>>> - return; >>>>>> + switch (prod->type) { >>>>>> + case IRQ_BYPASS_VFIO_PLATFORM: >>>>>> + kvm_vgic_unset_forwarding(irqfd->kvm, prod->irq, >>>>>> + irqfd->gsi + VGIC_NR_PRIVATE_IRQS); >>>>>> + break; >>>>>> >>>>>> - kvm_vgic_unset_forwarding(irqfd->kvm, prod->irq, >>>>>> - irqfd->gsi + VGIC_NR_PRIVATE_IRQS); >>>>>> + case IRQ_BYPASS_VFIO_PCI_MSI: >>>>>> + kvm_vgic_v4_unset_forwarding(irqfd->kvm, prod->irq, >>>>>> + &irqfd->irq_entry); >>>>>> + break; >>>>>> + } >>>>>> } >>>>>> >>>>>> void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *cons) >>>>>> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c >>>>>> index 207e1fda0dcd..338c86c5159f 100644 >>>>>> --- a/virt/kvm/arm/vgic/vgic-v4.c >>>>>> +++ b/virt/kvm/arm/vgic/vgic-v4.c >>>>>> @@ -72,3 +72,106 @@ void vgic_v4_teardown(struct kvm *kvm) >>>>>> its_vm->nr_vpes = 0; >>>>>> its_vm->vpes = NULL; >>>>>> } >>>>>> + >>>>>> +static struct vgic_its *vgic_get_its(struct kvm *kvm, >>>>>> + struct kvm_kernel_irq_routing_entry *irq_entry) >>>>>> +{ >>>>>> + struct kvm_msi msi = (struct kvm_msi) { >>>>>> + .address_lo = irq_entry->msi.address_lo, >>>>>> + .address_hi = irq_entry->msi.address_hi, >>>>>> + .data = irq_entry->msi.data, >>>>>> + .flags = irq_entry->msi.flags, >>>>>> + .devid = irq_entry->msi.devid, >>>>>> + }; >>>>>> + >>>>>> + /* >>>>>> + * Get a reference on the LPI. If NULL, this is not a valid >>>>>> + * translation for any of our vITSs. >>>>>> + */ >>>>>> + return vgic_msi_to_its(kvm, &msi); >>>>>> +} >>>>>> + >>>>>> +int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, >>>>>> + struct kvm_kernel_irq_routing_entry *irq_entry) >>>>>> +{ >>>>>> + struct vgic_its *its; >>>>>> + struct vgic_irq *irq; >>>>>> + struct its_vlpi_map map; >>>>>> + int ret; >>>>>> + >>>>>> + if (!vgic_is_v4_capable(kvm)) >>>>>> + return 0; >>>>>> + >>>>>> + /* >>>>>> + * Get the ITS, and escape early on error (not a valid >>>>>> + * doorbell for any of our vITSs). >>>>>> + */ >>>>>> + its = vgic_get_its(kvm, irq_entry); >>>>>> + if (IS_ERR(its)) >>>>>> + return 0; >>>>>> + >>>>>> + mutex_lock(&its->its_lock); >>>>>> + >>>>>> + /* Perform then actual DevID/EventID -> LPI translation. */ >>>>>> + ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, >>>>>> + irq_entry->msi.data, &irq); >>>>>> + if (ret) >>>>>> + goto out; >>>>>> + >>>>>> + /* >>>>>> + * Emit the mapping request. If it fails, the ITS probably >>>>>> + * isn't v4 compatible, so let's silently bail out. Holding >>>>>> + * the ITS lock should ensure that nothing can modify the >>>>>> + * target vcpu. >>>>>> + */ >>>>>> + map = (struct its_vlpi_map) { >>>>>> + .vm = &kvm->arch.vgic.its_vm, >>>>>> + .vintid = irq->intid, >>>>>> + .db_enabled = true, >>>>>> + .vpe_idx = irq->target_vcpu->vcpu_id, >>>> >>>> This is just wrong. We cannot assume that the vcpu_id has anything to do >>>> with the vpe_idx. It happens to be the same thing now, but the two things >>>> should be clearly disconnected. >>>> >>>> I suggest the following (untested): >>>> >>>> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c >>>> index cf5d6e2de6b8..0146e004401a 100644 >>>> --- a/virt/kvm/arm/vgic/vgic-v4.c >>>> +++ b/virt/kvm/arm/vgic/vgic-v4.c >>>> @@ -251,13 +251,27 @@ static void dump_routing(int virq, struct kvm_kernel_irq_routing_entry *irq_entr >>>> >>>> } >>>> >>>> +static int vgic_v4_vcpu_to_index(struct its_vm *its_vm, struct kvm_vcpu *vcpu) >>>> +{ >>>> + int i; >>>> + >>>> + for (i = 0; i < its_vm->nr_vpes; i++) { >>>> + struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; >>>> + >>>> + if (its_vm->vpes[i] == vpe) >>>> + return i; >>>> + } >>>> + >>>> + return -ENODEV; >>>> +} >>>> + >>> >>> Stupid question: Can we change the struct its_vlpi_map to contain a >>> vpe pointer or in stead of or in addition to the index? >> >> This is obviously the right solution, because the *index* of the VPE >> doesn't really matter for a map/unmap (it only matters for doorbell >> operations, and that's a very different code path). >> >> I came up with the following (untested, again), which is much more >> appealing: >> >> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c >> index b47097a3e4b4..0607541fcafc 100644 >> --- a/drivers/irqchip/irq-gic-v3-its.c >> +++ b/drivers/irqchip/irq-gic-v3-its.c >> @@ -900,7 +900,7 @@ static void its_send_vmapti(struct its_device *dev, u32 id) >> struct its_vlpi_map *map = &dev->event_map.vlpi_maps[id]; >> struct its_cmd_desc desc; >> >> - desc.its_vmapti_cmd.vpe = map->vm->vpes[map->vpe_idx]; >> + desc.its_vmapti_cmd.vpe = map->vpe; >> desc.its_vmapti_cmd.dev = dev; >> desc.its_vmapti_cmd.virt_id = map->vintid; >> desc.its_vmapti_cmd.event_id = id; >> @@ -914,7 +914,7 @@ static void its_send_vmovi(struct its_device *dev, u32 id) >> struct its_vlpi_map *map = &dev->event_map.vlpi_maps[id]; >> struct its_cmd_desc desc; >> >> - desc.its_vmovi_cmd.vpe = map->vm->vpes[map->vpe_idx]; >> + desc.its_vmovi_cmd.vpe = map->vpe; >> desc.its_vmovi_cmd.dev = dev; >> desc.its_vmovi_cmd.event_id = id; >> desc.its_vmovi_cmd.db_enabled = map->db_enabled; >> diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h >> index 52661b838821..58a4d89aa82c 100644 >> --- a/include/linux/irqchip/arm-gic-v4.h >> +++ b/include/linux/irqchip/arm-gic-v4.h >> @@ -62,15 +62,15 @@ struct its_vpe { >> * irq_set_vcpu_affinity(). >> * >> * @vm: Pointer to the GICv4 notion of a VM >> + * @vpe: Pointer to the GICv4 notion of a virtual CPU (VPE) >> * @vintid: Virtual LPI number >> * @db_enabled: Is the VPE doorbell to be generated? >> - * @vpe_idx: Index (0-based) of the VPE in this VM. Not the vpe_id! >> */ >> struct its_vlpi_map { >> struct its_vm *vm; >> + struct its_vpe *vpe; >> u32 vintid; >> bool db_enabled; >> - u16 vpe_idx; >> }; >> >> enum its_vcpu_info_cmd_type { >> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >> index d790d0c74b8b..6ba3d73e0f70 100644 >> --- a/virt/kvm/arm/vgic/vgic-its.c >> +++ b/virt/kvm/arm/vgic/vgic-its.c >> @@ -715,7 +715,7 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its, >> if (ret) >> return ret; >> >> - map.vpe_idx = vcpu->vcpu_id; >> + map.vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; >> >> return its_map_vlpi(ite->irq->host_irq, &map); >> } >> @@ -1184,7 +1184,7 @@ static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its, >> struct its_vlpi_map map; >> >> if (!its_get_vlpi(irq->host_irq, &map)) { >> - map.vpe_idx = vcpu2->vcpu_id; >> + map.vpe = &vcpu2->arch.vgic_cpu.vgic_v3.its_vpe; >> its_map_vlpi(irq->host_irq, &map); >> } >> } >> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c >> index cf5d6e2de6b8..6ece88322013 100644 >> --- a/virt/kvm/arm/vgic/vgic-v4.c >> +++ b/virt/kvm/arm/vgic/vgic-v4.c >> @@ -288,9 +288,9 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, >> */ >> map = (struct its_vlpi_map) { >> .vm = &kvm->arch.vgic.its_vm, >> + .vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe, >> .vintid = irq->intid, >> .db_enabled = true, >> - .vpe_idx = irq->target_vcpu->vcpu_id, >> }; >> >> if (its_map_vlpi(virq, &map)) >> >> Maybe I'll introduce a vcpu_to_vpe() helper, but it already looks much >> better to me... >> > Yes, indeed. Looks good to me as well. > > The only thing that makes me slightly nervous is the use of target_vcpu, > but I think we rely on it never being NULL for LPIs elsewhere in the > code, so we should be fine. Hmmm. Maybe not. When mapping an LPI, you can assign it to a collection that is not yet mapped to a redistributor, hence no target_vcpu. But in this case, vgic_its_resolve_lpi() fails, and we just don't enter this code path. Annoyingly, this also shows that I do not handle MAPC at all in this code, which is pretty embarrassing (I rely on MAPC being done before MAPI/MAPTI). I'll address that in the next version. Thanks, M. -- Jazz is not dead. It just smells funny...