From 0645211c43df0b96c51e12980066b3227e10b164 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Tue, 16 Nov 2010 22:30:03 +0100 Subject: KVM: Switch assigned device IRQ forwarding to threaded handler This improves the IRQ forwarding for assigned devices: By using the kernel's threaded IRQ scheme, we can get rid of the latency-prone work queue and simplify the code in the same run. Moreover, we no longer have to hold assigned_dev_lock while raising the guest IRQ, which can be a lenghty operation as we may have to iterate over all VCPUs. The lock is now only used for synchronizing masking vs. unmasking of INTx-type IRQs, thus is renames to intx_lock. Acked-by: Alex Williamson Acked-by: Michael S. Tsirkin Signed-off-by: Jan Kiszka Signed-off-by: Marcelo Tosatti --- include/linux/kvm_host.h | 12 +----- virt/kvm/assigned-dev.c | 107 +++++++++++++++-------------------------------- 2 files changed, 36 insertions(+), 83 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 2d63f2c0137c..9fe7fefe76b1 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -470,16 +470,8 @@ struct kvm_irq_ack_notifier { void (*irq_acked)(struct kvm_irq_ack_notifier *kian); }; -#define KVM_ASSIGNED_MSIX_PENDING 0x1 -struct kvm_guest_msix_entry { - u32 vector; - u16 entry; - u16 flags; -}; - struct kvm_assigned_dev_kernel { struct kvm_irq_ack_notifier ack_notifier; - struct work_struct interrupt_work; struct list_head list; int assigned_dev_id; int host_segnr; @@ -490,13 +482,13 @@ struct kvm_assigned_dev_kernel { bool host_irq_disabled; struct msix_entry *host_msix_entries; int guest_irq; - struct kvm_guest_msix_entry *guest_msix_entries; + struct msix_entry *guest_msix_entries; unsigned long irq_requested_type; int irq_source_id; int flags; struct pci_dev *dev; struct kvm *kvm; - spinlock_t assigned_dev_lock; + spinlock_t intx_lock; }; struct kvm_irq_mask_notifier { diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c index ecc4419fadca..1d77ce16360a 100644 --- a/virt/kvm/assigned-dev.c +++ b/virt/kvm/assigned-dev.c @@ -55,58 +55,31 @@ static int find_index_from_host_irq(struct kvm_assigned_dev_kernel return index; } -static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work) +static irqreturn_t kvm_assigned_dev_thread(int irq, void *dev_id) { - struct kvm_assigned_dev_kernel *assigned_dev; - int i; + struct kvm_assigned_dev_kernel *assigned_dev = dev_id; + u32 vector; + int index; - assigned_dev = container_of(work, struct kvm_assigned_dev_kernel, - interrupt_work); + if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_INTX) { + spin_lock(&assigned_dev->intx_lock); + disable_irq_nosync(irq); + assigned_dev->host_irq_disabled = true; + spin_unlock(&assigned_dev->intx_lock); + } - spin_lock_irq(&assigned_dev->assigned_dev_lock); if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) { - struct kvm_guest_msix_entry *guest_entries = - assigned_dev->guest_msix_entries; - for (i = 0; i < assigned_dev->entries_nr; i++) { - if (!(guest_entries[i].flags & - KVM_ASSIGNED_MSIX_PENDING)) - continue; - guest_entries[i].flags &= ~KVM_ASSIGNED_MSIX_PENDING; + index = find_index_from_host_irq(assigned_dev, irq); + if (index >= 0) { + vector = assigned_dev-> + guest_msix_entries[index].vector; kvm_set_irq(assigned_dev->kvm, - assigned_dev->irq_source_id, - guest_entries[i].vector, 1); + assigned_dev->irq_source_id, vector, 1); } } else kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id, assigned_dev->guest_irq, 1); - spin_unlock_irq(&assigned_dev->assigned_dev_lock); -} - -static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id) -{ - unsigned long flags; - struct kvm_assigned_dev_kernel *assigned_dev = - (struct kvm_assigned_dev_kernel *) dev_id; - - spin_lock_irqsave(&assigned_dev->assigned_dev_lock, flags); - if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) { - int index = find_index_from_host_irq(assigned_dev, irq); - if (index < 0) - goto out; - assigned_dev->guest_msix_entries[index].flags |= - KVM_ASSIGNED_MSIX_PENDING; - } - - schedule_work(&assigned_dev->interrupt_work); - - if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_GUEST_INTX) { - disable_irq_nosync(irq); - assigned_dev->host_irq_disabled = true; - } - -out: - spin_unlock_irqrestore(&assigned_dev->assigned_dev_lock, flags); return IRQ_HANDLED; } @@ -114,7 +87,6 @@ out: static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian) { struct kvm_assigned_dev_kernel *dev; - unsigned long flags; if (kian->gsi == -1) return; @@ -127,12 +99,12 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian) /* The guest irq may be shared so this ack may be * from another device. */ - spin_lock_irqsave(&dev->assigned_dev_lock, flags); + spin_lock(&dev->intx_lock); if (dev->host_irq_disabled) { enable_irq(dev->host_irq); dev->host_irq_disabled = false; } - spin_unlock_irqrestore(&dev->assigned_dev_lock, flags); + spin_unlock(&dev->intx_lock); } static void deassign_guest_irq(struct kvm *kvm, @@ -155,28 +127,19 @@ static void deassign_host_irq(struct kvm *kvm, struct kvm_assigned_dev_kernel *assigned_dev) { /* - * In kvm_free_device_irq, cancel_work_sync return true if: - * 1. work is scheduled, and then cancelled. - * 2. work callback is executed. - * - * The first one ensured that the irq is disabled and no more events - * would happen. But for the second one, the irq may be enabled (e.g. - * for MSI). So we disable irq here to prevent further events. + * We disable irq here to prevent further events. * * Notice this maybe result in nested disable if the interrupt type is * INTx, but it's OK for we are going to free it. * * If this function is a part of VM destroy, please ensure that till * now, the kvm state is still legal for probably we also have to wait - * interrupt_work done. + * on a currently running IRQ handler. */ if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) { int i; for (i = 0; i < assigned_dev->entries_nr; i++) - disable_irq_nosync(assigned_dev-> - host_msix_entries[i].vector); - - cancel_work_sync(&assigned_dev->interrupt_work); + disable_irq(assigned_dev->host_msix_entries[i].vector); for (i = 0; i < assigned_dev->entries_nr; i++) free_irq(assigned_dev->host_msix_entries[i].vector, @@ -188,8 +151,7 @@ static void deassign_host_irq(struct kvm *kvm, pci_disable_msix(assigned_dev->dev); } else { /* Deal with MSI and INTx */ - disable_irq_nosync(assigned_dev->host_irq); - cancel_work_sync(&assigned_dev->interrupt_work); + disable_irq(assigned_dev->host_irq); free_irq(assigned_dev->host_irq, (void *)assigned_dev); @@ -268,8 +230,9 @@ static int assigned_device_enable_host_intx(struct kvm *kvm, * on the same interrupt line is not a happy situation: there * are going to be long delays in accepting, acking, etc. */ - if (request_irq(dev->host_irq, kvm_assigned_dev_intr, - 0, "kvm_assigned_intx_device", (void *)dev)) + if (request_threaded_irq(dev->host_irq, NULL, kvm_assigned_dev_thread, + IRQF_ONESHOT, "kvm_assigned_intx_device", + (void *)dev)) return -EIO; return 0; } @@ -287,8 +250,8 @@ static int assigned_device_enable_host_msi(struct kvm *kvm, } dev->host_irq = dev->dev->irq; - if (request_irq(dev->host_irq, kvm_assigned_dev_intr, 0, - "kvm_assigned_msi_device", (void *)dev)) { + if (request_threaded_irq(dev->host_irq, NULL, kvm_assigned_dev_thread, + 0, "kvm_assigned_msi_device", (void *)dev)) { pci_disable_msi(dev->dev); return -EIO; } @@ -313,10 +276,10 @@ static int assigned_device_enable_host_msix(struct kvm *kvm, return r; for (i = 0; i < dev->entries_nr; i++) { - r = request_irq(dev->host_msix_entries[i].vector, - kvm_assigned_dev_intr, 0, - "kvm_assigned_msix_device", - (void *)dev); + r = request_threaded_irq(dev->host_msix_entries[i].vector, + NULL, kvm_assigned_dev_thread, + 0, "kvm_assigned_msix_device", + (void *)dev); if (r) goto err; } @@ -557,12 +520,10 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm, match->host_devfn = assigned_dev->devfn; match->flags = assigned_dev->flags; match->dev = dev; - spin_lock_init(&match->assigned_dev_lock); + spin_lock_init(&match->intx_lock); match->irq_source_id = -1; match->kvm = kvm; match->ack_notifier.irq_acked = kvm_assigned_dev_ack_irq; - INIT_WORK(&match->interrupt_work, - kvm_assigned_dev_interrupt_work_handler); list_add(&match->list, &kvm->arch.assigned_dev_head); @@ -654,9 +615,9 @@ static int kvm_vm_ioctl_set_msix_nr(struct kvm *kvm, r = -ENOMEM; goto msix_nr_out; } - adev->guest_msix_entries = kzalloc( - sizeof(struct kvm_guest_msix_entry) * - entry_nr->entry_nr, GFP_KERNEL); + adev->guest_msix_entries = + kzalloc(sizeof(struct msix_entry) * entry_nr->entry_nr, + GFP_KERNEL); if (!adev->guest_msix_entries) { kfree(adev->host_msix_entries); r = -ENOMEM; -- cgit v1.2.3