From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH v3 41/59] KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass Date: Wed, 30 Aug 2017 21:59:30 +0200 Message-ID: <20170830195930.GJ24522@cbox> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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 To: Marc Zyngier Return-path: Content-Disposition: inline In-Reply-To: <9fc83ca2-bdae-ffbc-9d81-c77c331b47d2@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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. Thanks, -Christoffer