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
]
Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
---
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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