An ioeventfd allows an eventfd to attach to a specific PIO/MMIO region in the
guest. Any guest-writes to that region will trigger an eventfd signal.
Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
---
libkvm-all.h | 44 +++++++++++++++++++++++++++++++++++++
qemu-kvm.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 113 insertions(+), 0 deletions(-)
diff --git a/libkvm-all.h b/libkvm-all.h
index e16646c..b21bb7e 100644
--- a/libkvm-all.h
+++ b/libkvm-all.h
@@ -943,6 +943,50 @@ int kvm_get_irq_route_gsi(kvm_context_t kvm);
*/
int kvm_irqfd(kvm_context_t kvm, int gsi, int flags);
+enum {
+ ioeventfd_option_pio,
+ ioeventfd_option_datamatch,
+};
+
+#define IOEVENTFD_FLAG_PIO (1 << ioeventfd_option_pio)
+#define IOEVENTFD_FLAG_DATAMATCH (1 << ioeventfd_option_datamatch)
+
+/*!
+ * \brief Assign an eventfd to an IO port (PIO or MMIO)
+ *
+ * Assigns an eventfd based file-descriptor to a specific PIO or MMIO
+ * address range. Any guest writes to the specified range will generate
+ * an eventfd signal.
+ *
+ * A data-match pointer can be optionally provided in "datamatch" and only
+ * writes which match this value exactly will generate an event. The length
+ * of the datamatch is established by the length of the overall IO range, and
+ * therefore must be in a natural byte-width for the IO routines of your
+ * particular architecture (e.g. 1, 2, 4, or 8 bytes on x86_64).
+ *
+ * \param kvm Pointer to the current kvm_context
+ * \param addr The IO address
+ * \param len The length of the IO region at the address
+ * \param fd The eventfd file-descriptor
+ * \param datamatch A optional data-match token
+ * \param flags FLAG_PIO: PIO, else MMIO, FLAG_DATAMATCH, datamatch valid
+ */
+int kvm_assign_ioeventfd(kvm_context_t kvm, unsigned long addr, size_t len,
+ int fd, __u64 datamatch, int flags);
+
+/*!
+ * \brief Deassign an ioeventfd from a previously registered IO port
+ *
+ * Deassigns an ioeventfd previously registered with kvm_assign_ioeventfd()
+ *
+ * \param kvm Pointer to the current kvm_context
+ * \param addr The IO address to deassign
+ * \param fd The eventfd file-descriptor
+ * \param flags FLAG_PIO: PIO, else MMIO
+ */
+int kvm_deassign_ioeventfd(kvm_context_t kvm, unsigned long addr,
+ int fd, int flags);
+
#ifdef KVM_CAP_DEVICE_MSIX
int kvm_assign_set_msix_nr(kvm_context_t kvm,
struct kvm_assigned_msix_nr *msix_nr);
diff --git a/qemu-kvm.c b/qemu-kvm.c
index 982ad33..ae77e0a 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -1688,6 +1688,75 @@ int kvm_irqfd(kvm_context_t kvm, int gsi, int flags)
}
#endif /* KVM_CAP_IRQFD */
+
+#ifdef KVM_CAP_IOEVENTFD
+
+#include <sys/eventfd.h>
+
+int kvm_assign_ioeventfd(kvm_context_t kvm, unsigned long addr, size_t len,
+ int fd, __u64 datamatch, int flags)
+{
+ int r;
+ int type = flags & IOEVENTFD_FLAG_PIO;
+ struct kvm_ioeventfd data = {
+ .datamatch = datamatch,
+ .addr = addr,
+ .len = len,
+ .fd = fd,
+ };
+
+ data.flags |= flags & IOEVENTFD_FLAG_DATAMATCH ?
+ KVM_IOEVENTFD_FLAG_DATAMATCH : 0;
+ data.flags |= type ? KVM_IOEVENTFD_FLAG_PIO : 0;
+
+ if (!kvm_check_extension(kvm, KVM_CAP_IOEVENTFD))
+ return -ENOENT;
+
+ r = ioctl(kvm->vm_fd, KVM_IOEVENTFD, &data);
+ if (r == -1)
+ r = -errno;
+ return r;
+}
+
+int kvm_deassign_ioeventfd(kvm_context_t kvm, unsigned long addr, int fd,
+ int flags)
+{
+ int r;
+ int type = flags & IOEVENTFD_FLAG_PIO;
+ struct kvm_ioeventfd data = {
+ .addr = addr,
+ .fd = fd,
+ .flags = KVM_IOEVENTFD_FLAG_DEASSIGN |
+ (type ? KVM_IOEVENTFD_FLAG_PIO : 0),
+ };
+
+ if (!kvm_check_extension(kvm, KVM_CAP_IOEVENTFD))
+ return -ENOENT;
+
+ r = ioctl(kvm->vm_fd, KVM_IOEVENTFD, &data);
+ if (r == -1)
+ r = -errno;
+ return r;
+}
+
+#else /* KVM_CAP_IOEVENTFD */
+
+int kvm_assign_ioeventfd(kvm_context_t kvm, unsigned long addr, size_t len,
+ int fd, __u64 datamatch, int flags)
+{
+ return -ENOSYS;
+}
+
+int kvm_deassign_ioeventfd(kvm_context_t kvm, unsigned long addr, int fd,
+ int flags)
+{
+ return -ENOSYS;
+}
+
+#endif /* KVM_CAP_IOEVENTFD */
+
+
+
static inline unsigned long kvm_get_thread_id(void)
{
return syscall(SYS_gettid);
--
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