ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/marvell/linux/drivers/xen/xenbus/xenbus_dev_backend.c b/marvell/linux/drivers/xen/xenbus/xenbus_dev_backend.c
new file mode 100644
index 0000000..edba5fe
--- /dev/null
+++ b/marvell/linux/drivers/xen/xenbus/xenbus_dev_backend.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/init.h>
+#include <linux/capability.h>
+
+#include <xen/xen.h>
+#include <xen/page.h>
+#include <xen/xenbus.h>
+#include <xen/xenbus_dev.h>
+#include <xen/grant_table.h>
+#include <xen/events.h>
+#include <asm/xen/hypervisor.h>
+
+#include "xenbus.h"
+
+static int xenbus_backend_open(struct inode *inode, struct file *filp)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ return nonseekable_open(inode, filp);
+}
+
+static long xenbus_alloc(domid_t domid)
+{
+ struct evtchn_alloc_unbound arg;
+ int err = -EEXIST;
+
+ xs_suspend();
+
+ /* If xenstored_ready is nonzero, that means we have already talked to
+ * xenstore and set up watches. These watches will be restored by
+ * xs_resume, but that requires communication over the port established
+ * below that is not visible to anyone until the ioctl returns.
+ *
+ * This can be resolved by splitting the ioctl into two parts
+ * (postponing the resume until xenstored is active) but this is
+ * unnecessarily complex for the intended use where xenstored is only
+ * started once - so return -EEXIST if it's already running.
+ */
+ if (xenstored_ready)
+ goto out_err;
+
+ gnttab_grant_foreign_access_ref(GNTTAB_RESERVED_XENSTORE, domid,
+ virt_to_gfn(xen_store_interface), 0 /* writable */);
+
+ arg.dom = DOMID_SELF;
+ arg.remote_dom = domid;
+
+ err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &arg);
+ if (err)
+ goto out_err;
+
+ if (xen_store_evtchn > 0)
+ xb_deinit_comms();
+
+ xen_store_evtchn = arg.port;
+
+ xs_resume();
+
+ return arg.port;
+
+ out_err:
+ xs_suspend_cancel();
+ return err;
+}
+
+static long xenbus_backend_ioctl(struct file *file, unsigned int cmd,
+ unsigned long data)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ switch (cmd) {
+ case IOCTL_XENBUS_BACKEND_EVTCHN:
+ if (xen_store_evtchn > 0)
+ return xen_store_evtchn;
+ return -ENODEV;
+ case IOCTL_XENBUS_BACKEND_SETUP:
+ return xenbus_alloc(data);
+ default:
+ return -ENOTTY;
+ }
+}
+
+static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ size_t size = vma->vm_end - vma->vm_start;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))
+ return -EINVAL;
+
+ if (remap_pfn_range(vma, vma->vm_start,
+ virt_to_pfn(xen_store_interface),
+ size, vma->vm_page_prot))
+ return -EAGAIN;
+
+ return 0;
+}
+
+static const struct file_operations xenbus_backend_fops = {
+ .open = xenbus_backend_open,
+ .mmap = xenbus_backend_mmap,
+ .unlocked_ioctl = xenbus_backend_ioctl,
+};
+
+static struct miscdevice xenbus_backend_dev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "xen/xenbus_backend",
+ .fops = &xenbus_backend_fops,
+};
+
+static int __init xenbus_backend_init(void)
+{
+ int err;
+
+ if (!xen_initial_domain())
+ return -ENODEV;
+
+ err = misc_register(&xenbus_backend_dev);
+ if (err)
+ pr_err("Could not register xenbus backend device\n");
+ return err;
+}
+device_initcall(xenbus_backend_init);