+
+ eventfd_signal(iofd->ctx, 1);
+ return 0;
+}
+
+static struct gh_vm_io_handler_ops io_ops = {
+ .write = gh_write_ioeventfd,
+};
+
+static long gh_ioeventfd_bind(struct gh_vm_function_instance *f)
+{
+ const struct gh_fn_ioeventfd_arg *args = f->argp;
+ struct gh_ioeventfd *iofd;
+ struct eventfd_ctx *ctx;
+ int ret;
+
+ if (f->arg_size != sizeof(*args))
+ return -EINVAL;
+
+ /* All other flag bits are reserved for future use */
+ if (args->flags & ~GH_IOEVENTFD_FLAGS_DATAMATCH)
+ return -EINVAL;
+
+ /* must be natural-word sized, or 0 to ignore length */
+ switch (args->len) {
+ case 0:
+ case 1:
+ case 2:
+ case 4:
+ case 8:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* check for range overflow */
+ if (overflows_type(args->addr + args->len, u64))
+ return -EINVAL;
+
+ /* ioeventfd with no length can't be combined with DATAMATCH */
+ if (!args->len && (args->flags & GH_IOEVENTFD_FLAGS_DATAMATCH))
+ return -EINVAL;
+
+ ctx = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ iofd = kzalloc(sizeof(*iofd), GFP_KERNEL);
+ if (!iofd) {
+ ret = -ENOMEM;
+ goto err_eventfd;
+ }
+
+ f->data = iofd;
+ iofd->f = f;
+
+ iofd->ctx = ctx;
+
+ if (args->flags & GH_IOEVENTFD_FLAGS_DATAMATCH) {
+ iofd->io_handler.datamatch = true;
+ iofd->io_handler.len = args->len;
+ iofd->io_handler.data = args->datamatch;
+ }
+ iofd->io_handler.addr = args->addr;
+ iofd->io_handler.ops = &io_ops;
+
+ ret = gh_vm_add_io_handler(f->ghvm, &iofd->io_handler);
+ if (ret)
+ goto err_io_dev_add;
+
+ return 0;
+
+err_io_dev_add:
+ kfree(iofd);
+err_eventfd:
+ eventfd_ctx_put(ctx);
+ return ret;
+}
+
+static void gh_ioevent_unbind(struct gh_vm_function_instance *f)
+{
+ struct gh_ioeventfd *iofd = f->data;
+
+ eventfd_ctx_put(iofd->ctx);
+ gh_vm_remove_io_handler(iofd->f->ghvm, &iofd->io_handler);
+ kfree(iofd);
+}
+
+static bool gh_ioevent_compare(const struct gh_vm_function_instance *f,
+ const void *arg, size_t size)
+{
+ const struct gh_fn_ioeventfd_arg *instance = f->argp,
+ *other = arg;
+
+ if (sizeof(*other) != size)
+ return false;
+
+ return instance->addr == other->addr;
+}
+
+DECLARE_GH_VM_FUNCTION_INIT(ioeventfd, GH_FN_IOEVENTFD, 3,
+ gh_ioeventfd_bind, gh_ioevent_unbind,
+ gh_ioevent_compare);
+MODULE_DESCRIPTION("Gunyah ioeventfd VM Function");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
index 0c480c622686..fa1cae7419d2 100644
--- a/include/uapi/linux/gunyah.h
+++ b/include/uapi/linux/gunyah.h
@@ -79,10 +79,13 @@ struct gh_vm_dtb_config {
* Return: file descriptor to manipulate the vcpu.
* @GH_FN_IRQFD: register eventfd to assert a Gunyah doorbell
* &struct gh_fn_desc.arg is a pointer to &struct
gh_fn_irqfd_arg
+ * @GH_FN_IOEVENTFD: register ioeventfd to trigger when VM faults on
parameter
+ * &struct gh_fn_desc.arg is a pointer to &struct
gh_fn_ioeventfd_arg
*/
enum gh_fn_type {
GH_FN_VCPU = 1,
GH_FN_IRQFD,
+ GH_FN_IOEVENTFD,
};
#define GH_FN_MAX_ARG_SIZE 256
@@ -134,6 +137,40 @@ struct gh_fn_irqfd_arg {
__u32 padding;
};
+/**
+ * enum gh_ioeventfd_flags - flags for use in gh_fn_ioeventfd_arg
+ * @GH_IOEVENTFD_FLAGS_DATAMATCH: the event will be signaled only if the
+ * written value to the registered
address is
+ * equal to &struct
gh_fn_ioeventfd_arg.datamatch
+ */
+enum gh_ioeventfd_flags {
+ GH_IOEVENTFD_FLAGS_DATAMATCH = 1UL << 0,
+};
+
+/**
+ * struct gh_fn_ioeventfd_arg - Arguments to create an ioeventfd
function
+ * @datamatch: data used when GH_IOEVENTFD_DATAMATCH is set
+ * @addr: Address in guest memory
+ * @len: Length of access
+ * @fd: When ioeventfd is matched, this eventfd is written
+ * @flags: See &enum gh_ioeventfd_flags
+ * @padding: padding bytes
+ *
+ * Create this function with &GH_VM_ADD_FUNCTION using type
&GH_FN_IOEVENTFD.
+ *
+ * Attaches an ioeventfd to a legal mmio address within the guest. A
guest write
+ * in the registered address will signal the provided event instead
of triggering
+ * an exit on the GH_VCPU_RUN ioctl.
+ */
+struct gh_fn_ioeventfd_arg {
+ __u64 datamatch;
+ __u64 addr; /* legal mmio address */
+ __u32 len; /* 1, 2, 4, or 8 bytes; or 0 to ignore length */
+ __s32 fd;
+ __u32 flags;
+ __u32 padding;
+};
+
/**
* struct gh_fn_desc - Arguments to create a VM function
* @type: Type of the function. See &enum gh_fn_type.
