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Commit f1d1c309 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Marcelo Tosatti
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KVM: only allow one gsi per fd 



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.

Cc: stable@kernel.org
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Acked-by: default avatarAcked-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 82b7005f

virt/kvm/eventfd.c

+13 −2
Original line number Diff line number Diff line
@@ -166,7 +166,7 @@ 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;
@@ -203,9 +203,20 @@ 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);