From f0d13b89d4b12f331a0dd1d646a69060e49b1951 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 13 Jan 2010 18:58:09 +0200 Subject: [PATCH 1/1] KVM: only allow one gsi per fd commit f1d1c309f35e9b0fb961cffd70fbd04f450ec47c upstream. Looks like repeatedly binding same fd to multiple gsi's with irqfd can use up a ton of kernel memory for irqfd structures. A simple fix is to allow each fd to only trigger one gsi: triggering a storm of interrupts in guest is likely useless anyway, and we can do it by binding a single gsi to many interrupts if we really want to. Signed-off-by: Michael S. Tsirkin Acked-by: Acked-by: Gregory Haskins Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- virt/kvm/eventfd.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index bb4ebd89b9ff..251282c43ac8 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -168,7 +168,7 @@ irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh, static int kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi) { - struct _irqfd *irqfd; + struct _irqfd *irqfd, *tmp; struct file *file = NULL; struct eventfd_ctx *eventfd = NULL; int ret; @@ -205,9 +205,20 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi) init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc); + spin_lock_irq(&kvm->irqfds.lock); + + ret = 0; + list_for_each_entry(tmp, &kvm->irqfds.items, list) { + if (irqfd->eventfd != tmp->eventfd) + continue; + /* This fd is used for another irq already. */ + ret = -EBUSY; + spin_unlock_irq(&kvm->irqfds.lock); + goto fail; + } + events = file->f_op->poll(file, &irqfd->pt); - spin_lock_irq(&kvm->irqfds.lock); list_add_tail(&irqfd->list, &kvm->irqfds.items); spin_unlock_irq(&kvm->irqfds.lock); -- 2.39.2