Re: [KVM PATCH v4 2/2] kvm: add support for irqfd via eventfd-notificationinterface

From: Avi Kivity
Date: Tue May 05 2009 - 11:45:32 EST


Gregory Haskins wrote:
KVM provides a complete virtual system environment for guests, including
support for injecting interrupts modeled after the real exception/interrupt
facilities present on the native platform (such as the IDT on x86).
Virtual interrupts can come from a variety of sources (emulated devices,
pass-through devices, etc) but all must be injected to the guest via
the KVM infrastructure. This patch adds a new mechanism to inject a specific
interrupt to a guest using a decoupled eventfd mechnanism: Any legal signal
on the irqfd (using eventfd semantics from either userspace or kernel) will
translate into an injected interrupt in the guest at the next available
interrupt window.

+struct kvm_irqfd {
+ __u32 gsi;
+ __u32 flags;
+};
+

Please add some reserved space here.

+int
+kvm_irqfd(struct kvm *kvm, int gsi, int flags)
+{
+ struct _irqfd *irqfd;
+ struct file *file = NULL;
+ int fd = -1;
+ int ret;
+
+ irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
+ if (!irqfd)
+ return -ENOMEM;
+
+ irqfd->kvm = kvm;

You need to increase the refcount on struct kvm here. Otherwise evil userspace will create an irqfd, close the vm and vcpu fds, and inject an interrupt.

Otherwise, looks good.

--
error compiling committee.c: too many arguments to function

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