Hi David, See inline for an answer to your last question: Gregory Haskins wrote: > This allows an eventfd to be registered as an irq source with a guest. Any > signaling operation on the eventfd (via userspace or kernel) will inject > the registered GSI at the next available window. > > Signed-off-by: Gregory Haskins <[email protected]> > --- > > arch/x86/kvm/Makefile | 2 - > arch/x86/kvm/x86.c | 1 > include/linux/kvm.h | 7 ++ > include/linux/kvm_host.h | 7 ++ > virt/kvm/irqfd.c | 146 > ++++++++++++++++++++++++++++++++++++++++++++++ > virt/kvm/kvm_main.c | 12 ++++ > 6 files changed, 174 insertions(+), 1 deletions(-) > create mode 100644 virt/kvm/irqfd.c > > diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile > index b43c4ef..d5fff51 100644 > --- a/arch/x86/kvm/Makefile > +++ b/arch/x86/kvm/Makefile > @@ -3,7 +3,7 @@ > # > > common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o \ > - coalesced_mmio.o irq_comm.o) > + coalesced_mmio.o irq_comm.o irqfd.o) > ifeq ($(CONFIG_KVM_TRACE),y) > common-objs += $(addprefix ../../../virt/kvm/, kvm_trace.o) > endif > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8cb8542..88c45e6 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1027,6 +1027,7 @@ int kvm_dev_ioctl_check_extension(long ext) > case KVM_CAP_REINJECT_CONTROL: > case KVM_CAP_IRQ_INJECT_STATUS: > case KVM_CAP_ASSIGN_DEV_IRQ: > + case KVM_CAP_IRQFD: > r = 1; > break; > case KVM_CAP_COALESCED_MMIO: > diff --git a/include/linux/kvm.h b/include/linux/kvm.h > index 3db5d8d..2404775 100644 > --- a/include/linux/kvm.h > +++ b/include/linux/kvm.h > @@ -415,6 +415,7 @@ struct kvm_trace_rec { > #define KVM_CAP_ASSIGN_DEV_IRQ 29 > /* Another bug in KVM_SET_USER_MEMORY_REGION fixed: */ > #define KVM_CAP_JOIN_MEMORY_REGIONS_WORKS 30 > +#define KVM_CAP_IRQFD 31 > > #ifdef KVM_CAP_IRQ_ROUTING > > @@ -454,6 +455,11 @@ struct kvm_irq_routing { > > #endif > > +struct kvm_irqfd { > + __u32 fd; > + __u32 gsi; > +}; > + > /* > * ioctls for VM fds > */ > @@ -498,6 +504,7 @@ struct kvm_irq_routing { > #define KVM_ASSIGN_SET_MSIX_ENTRY \ > _IOW(KVMIO, 0x74, struct kvm_assigned_msix_entry) > #define KVM_DEASSIGN_DEV_IRQ _IOW(KVMIO, 0x75, struct kvm_assigned_irq) > +#define KVM_ASSIGN_IRQFD _IOW(KVMIO, 0x76, struct kvm_irqfd) > > /* > * ioctls for vcpu fds > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 095ebb6..57f8dfe 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -134,6 +134,10 @@ struct kvm { > struct list_head vm_list; > struct kvm_io_bus mmio_bus; > struct kvm_io_bus pio_bus; > + struct { > + struct list_head items; > + int src; > + } irqfd; > struct kvm_vm_stat stat; > struct kvm_arch arch; > atomic_t users_count; > @@ -524,4 +528,7 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) > {} > > #endif > > +int kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi); > +void kvm_irqfd_release(struct kvm *kvm); > + > #endif > diff --git a/virt/kvm/irqfd.c b/virt/kvm/irqfd.c > new file mode 100644 > index 0000000..d2e0915 > --- /dev/null > +++ b/virt/kvm/irqfd.c > @@ -0,0 +1,146 @@ > +/* > + * irqfd: Allows an eventfd to be used to inject an interrupt to the guest > + * > + * Credit goes to Avi Kivity for the original idea. > + * > + * Copyright 2009 Novell. All Rights Reserved. > + * > + * Author: > + * Gregory Haskins <[email protected]> > + * > + * This file is free software; you can redistribute it and/or modify > + * it under the terms of version 2 of the GNU General Public License > + * as published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, write to the Free Software Foundation, > + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. > + */ > + > +#include <linux/kvm_host.h> > +#include <linux/eventfd.h> > +#include <linux/workqueue.h> > +#include <linux/wait.h> > +#include <linux/poll.h> > +#include <linux/file.h> > +#include <linux/list.h> > + > +struct _irqfd { > + struct kvm *kvm; > + int gsi; > + struct file *file; > + struct list_head list; > + poll_table pt; > + wait_queue_head_t *wqh; > + wait_queue_t wait; > + struct work_struct work; > +}; > + > +static void > +irqfd_inject(struct work_struct *work) > +{ > + struct _irqfd *irqfd = container_of(work, struct _irqfd, work); > + struct kvm *kvm = irqfd->kvm; > + > + mutex_lock(&kvm->lock); > + kvm_set_irq(kvm, kvm->irqfd.src, irqfd->gsi, 1); > + mutex_unlock(&kvm->lock); > +} > + > +static int > +irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key) > +{ > + struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait); > + > + /* > + * The eventfd calls its wake_up with interrupts disabled, > + * so we need to defer the IRQ injection until later since we need > + * to acquire the kvm->lock to do so. > + */ > + schedule_work(&irqfd->work); > + > + return 0; > +} > + > +static void > +irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh, > + poll_table *pt) > +{ > + struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt); > + > + irqfd->wqh = wqh; > + add_wait_queue(wqh, &irqfd->wait); > +} > + > +int > +kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi) > +{ > + struct _irqfd *irqfd; > + struct file *file; > + int ret; > + > + irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL); > + if (!irqfd) > + return -ENOMEM; > + > + irqfd->kvm = kvm; > + irqfd->gsi = gsi; > + INIT_LIST_HEAD(&irqfd->list); > + init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); > + init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc); > + INIT_WORK(&irqfd->work, irqfd_inject); > + > + file = eventfd_fget(fd); >
I grab the fget() reference here, and I hold it until after I have
already called remove_wait_queue()...
> + if (IS_ERR(file)) {
> + ret = PTR_ERR(file);
> + goto fail;
> + }
> +
> + ret = file->f_op->poll(file, &irqfd->pt);
> + /* do we need to look for errors in ret? */
> +
> + irqfd->file = file;
> +
> + mutex_lock(&kvm->lock);
> + if (kvm->irqfd.src == -1) {
> + ret = kvm_request_irq_source_id(kvm);
> + BUG_ON(ret < 0);
> +
> + kvm->irqfd.src = ret;
> + }
> +
> + list_add_tail(&irqfd->list, &kvm->irqfd.items);
> +
> + mutex_unlock(&kvm->lock);
> +
> + return 0;
> +
> +fail:
> + kfree(irqfd);
> + return ret;
> +}
> +
> +void
> +kvm_irqfd_release(struct kvm *kvm)
> +{
> + struct _irqfd *irqfd, *tmp;
> +
> + list_for_each_entry_safe(irqfd, tmp, &kvm->irqfd.items, list) {
> + remove_wait_queue(irqfd->wqh, &irqfd->wait);
> +
> + flush_work(&irqfd->work);
> + fput(irqfd->file);
>
... here.
Please let me know if you see any holes in that approach.
-Greg
> +
> + list_del(&irqfd->list);
> + kfree(irqfd);
> + }
> +
> + if (kvm->irqfd.src != -1)
> + kvm_free_irq_source_id(kvm, kvm->irqfd.src);
> +
> +}
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3265566..c822d79 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -972,6 +972,8 @@ static struct kvm *kvm_create_vm(void)
> atomic_inc(&kvm->mm->mm_count);
> spin_lock_init(&kvm->mmu_lock);
> kvm_io_bus_init(&kvm->pio_bus);
> + INIT_LIST_HEAD(&kvm->irqfd.items);
> + kvm->irqfd.src = -1;
> mutex_init(&kvm->lock);
> kvm_io_bus_init(&kvm->mmio_bus);
> init_rwsem(&kvm->slots_lock);
> @@ -1023,6 +1025,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
> spin_lock(&kvm_lock);
> list_del(&kvm->vm_list);
> spin_unlock(&kvm_lock);
> + kvm_irqfd_release(kvm);
> kvm_free_irq_routing(kvm);
> kvm_io_bus_destroy(&kvm->pio_bus);
> kvm_io_bus_destroy(&kvm->mmio_bus);
> @@ -2197,6 +2200,15 @@ static long kvm_vm_ioctl(struct file *filp,
> }
> #endif
> #endif /* KVM_CAP_IRQ_ROUTING */
> + case KVM_ASSIGN_IRQFD: {
> + struct kvm_irqfd data;
> +
> + r = -EFAULT;
> + if (copy_from_user(&data, argp, sizeof data))
> + goto out;
> + r = kvm_irqfd_assign(kvm, data.fd, data.gsi);
> + break;
> + }
> default:
> r = kvm_arch_vm_ioctl(filp, ioctl, arg);
> }
>
> --
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