Re: [PATCH v8] qemu-kvm: add irqfd support

[Gregory Haskins <ghaskins@novell.com>]

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Gregory Haskins wrote:
> irqfd lets you create an eventfd based file-desriptor to inject interrupts
> to a kvm guest.  We associate one gsi per fd for fine-grained routing.
>
> [note: this is meant to work in conjunction with the POLLHUP version of
>  irqfd, which has not yet been accepted into kvm.git]
>
> [ Changelog:
>
>     v8:
>         *) removed deassign() verb in favor of POLLHUP support on close()
>         *) only include sys/eventfd.h if CAP_IRQFD is defined to properly
>            support older kernels
>         *) s/ENOENT/ENOSYS
> ] 
>   

Hmm..it would appear I already released a 'v8' in the past. :(

In any case, this is the latest version to consider

-Greg

> Signed-off-by: Gregory Haskins <ghaskins@novell.com>
> ---
>
>  kvm/libkvm/libkvm.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
>  kvm/libkvm/libkvm.h |   14 ++++++++++++++
>  2 files changed, 63 insertions(+), 0 deletions(-)
>
> diff --git a/kvm/libkvm/libkvm.c b/kvm/libkvm/libkvm.c
> index ba0a5d1..10cb2ac 100644
> --- a/kvm/libkvm/libkvm.c
> +++ b/kvm/libkvm/libkvm.c
> @@ -1444,3 +1444,52 @@ int kvm_assign_set_msix_entry(kvm_context_t kvm,
>          return ret;
>  }
>  #endif
> +
> +#ifdef KVM_CAP_IRQFD
> +
> +#include <sys/eventfd.h>
> +
> +static int _kvm_irqfd(kvm_context_t kvm, int fd, int gsi, int flags)
> +{
> +	int r;
> +	struct kvm_irqfd data = {
> +		.fd    = fd,
> +		.gsi   = gsi,
> +		.flags = flags,
> +	};
> +
> +	r = ioctl(kvm->vm_fd, KVM_IRQFD, &data);
> +	if (r == -1)
> +		r = -errno;
> +	return r;
> +}
> +
> +int kvm_irqfd(kvm_context_t kvm, int gsi, int flags)
> +{
> +	int r;
> +	int fd;
> +
> +	if (!kvm_check_extension(kvm, KVM_CAP_IRQFD))
> +		return -ENOENT;
> +
> +	fd = eventfd(0, 0);
> +	if (fd < 0)
> +		return -errno;
> +
> +	r = _kvm_irqfd(kvm, fd, gsi, 0);
> +	if (r < 0) {
> +		close(fd);
> +		return -errno;
> +	}
> +
> +	return fd;
> +}
> +
> +#else /* KVM_CAP_IRQFD */
> +
> +int kvm_irqfd(kvm_context_t kvm, int gsi, int flags)
> +{
> +	return -ENOSYS;
> +}
> +
> +#endif /* KVM_CAP_IRQFD */
> diff --git a/kvm/libkvm/libkvm.h b/kvm/libkvm/libkvm.h
> index 4821a1e..aca8ed6 100644
> --- a/kvm/libkvm/libkvm.h
> +++ b/kvm/libkvm/libkvm.h
> @@ -856,6 +856,20 @@ int kvm_commit_irq_routes(kvm_context_t kvm);
>   */
>  int kvm_get_irq_route_gsi(kvm_context_t kvm);
>  
> +/*!
> + * \brief Create a file descriptor for injecting interrupts
> + *
> + * Creates an eventfd based file-descriptor that maps to a specific GSI
> + * in the guest.  eventfd compliant signaling (write() from userspace, or
> + * eventfd_signal() from kernelspace) will cause the GSI to inject
> + * itself into the guest at the next available window.
> + *
> + * \param kvm Pointer to the current kvm_context
> + * \param gsi GSI to assign to this fd
> + * \param flags reserved, must be zero
> + */
> +int kvm_irqfd(kvm_context_t kvm, int gsi, int flags);
> +
>  #ifdef KVM_CAP_DEVICE_MSIX
>  int kvm_assign_set_msix_nr(kvm_context_t kvm,
>  			   struct kvm_assigned_msix_nr *msix_nr);
>
> --
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>   



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