--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * xen/common/dt-overlay.c
+ *
+ * Device tree overlay support in Xen.
+ *
+ * Copyright (C) 2023, Advanced Micro Devices, Inc. All Rights Reserved.
+ * Written by Vikram Garhwal <vikram.garhwal@amd.com>
+ *
+ */
+#include <asm/domain_build.h>
+#include <xen/dt-overlay.h>
+#include <xen/guest_access.h>
+#include <xen/iocap.h>
+#include <xen/libfdt/libfdt.h>
+#include <xen/xmalloc.h>
+
+static LIST_HEAD(overlay_tracker);
+static DEFINE_SPINLOCK(overlay_lock);
+
+/* Find last descendants of the device_node. */
+static struct dt_device_node *
+find_last_descendants_node(const struct dt_device_node *device_node)
+{
+ struct dt_device_node *child_node;
+
+ for ( child_node = device_node->child; child_node->sibling != NULL;
+ child_node = child_node->sibling );
+
+ /* If last child_node also have children. */
+ if ( child_node->child )
+ child_node = find_last_descendants_node(child_node);
+
+ return child_node;
+}
+
+static int dt_overlay_remove_node(struct dt_device_node *device_node)
+{
+ struct dt_device_node *np;
+ struct dt_device_node *parent_node;
+ struct dt_device_node *last_descendant = device_node->child;
+
+ parent_node = device_node->parent;
+
+ /* Check if we are trying to remove "/" i.e. root node. */
+ if ( parent_node == NULL )
+ {
+ dt_dprintk("%s's parent node not found\n", device_node->name);
+ return -EFAULT;
+ }
+
+ /* Sanity check for linking between parent and child node. */
+ np = parent_node->child;
+ if ( np == NULL )
+ {
+ dt_dprintk("parent node %s's not found\n", parent_node->name);
+ return -EFAULT;
+ }
+
+ /* If node to be removed is only child node or first child. */
+ if ( !dt_node_cmp(np->full_name, device_node->full_name) )
+ {
+ parent_node->child = np->sibling;
+
+ /*
+ * Iterate over all child nodes of device_node. Given that we are
+ * removing a node, we need to remove all it's descendants too.
+ * Reason behind finding last_descendant:
+ * If device_node has multiple children, device_node->allnext will point
+ * to first_child and first_child->allnext will be a sibling. When the
+ * device_node and it's all children are removed, parent_node->allnext
+ * should point to node next to last children.
+ */
+ if ( last_descendant )
+ {
+ last_descendant = find_last_descendants_node(device_node);
+ parent_node->allnext = last_descendant->allnext;
+ }
+ else
+ parent_node->allnext = np->allnext;
+
+ return 0;
+ }
+
+ for ( np = parent_node->child; np->sibling != NULL; np = np->sibling )
+ {
+ if ( !dt_node_cmp(np->sibling->full_name, device_node->full_name) )
+ {
+ /* Found the node. Now we remove it. */
+ np->sibling = np->sibling->sibling;
+
+ if ( np->child )
+ np = find_last_descendants_node(np);
+
+ /*
+ * Iterate over all child nodes of device_node. Given that we are
+ * removing parent node, we need to remove all it's descendants too.
+ */
+ if ( last_descendant )
+ last_descendant = find_last_descendants_node(device_node);
+
+ if ( last_descendant )
+ np->allnext = last_descendant->allnext;
+ else
+ np->allnext = np->allnext->allnext;
+
+ break;
+ }
+ }
+
+ return 0;
+}
+
+/* Basic sanity check for the dtbo tool stack provided to Xen. */
+static int check_overlay_fdt(const void *overlay_fdt, uint32_t overlay_fdt_size)
+{
+ if ( (fdt_totalsize(overlay_fdt) != overlay_fdt_size) ||
+ fdt_check_header(overlay_fdt) )
+ {
+ printk(XENLOG_ERR "The overlay FDT is not a valid Flat Device Tree\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int irq_remove_cb(unsigned long s, unsigned long e, void *dom,
+ unsigned long *c)
+{
+ int rc;
+ struct domain *d = dom;
+
+ /*
+ * TODO: We don't handle shared IRQs for now. So, it is assumed that
+ * the IRQs was not shared with another devices.
+ * TODO: Undo the IRQ routing.
+ */
+ rc = irq_deny_access(d, s);
+ if ( rc )
+ {
+ printk(XENLOG_ERR "unable to revoke access for irq %lu\n", s);
+ }
+ else
+ *c += e - s + 1;
+
+ return rc;
+
+}
+
+static int iomem_remove_cb(unsigned long s, unsigned long e, void *dom,
+ unsigned long *c)
+{
+ int rc;
+ struct domain *d = dom;
+
+ /*
+ * Remove mmio access.
+ * TODO: Support for remove/add the mapping in P2M.
+ */
+ rc = iomem_deny_access(d, s, e);
+ if ( rc )
+ {
+ printk(XENLOG_ERR "Unable to remove dom%d access to"
+ " 0x%"PRIx64" - 0x%"PRIx64"\n",
+ d->domain_id,
+ s & PAGE_MASK, PAGE_ALIGN(e) - 1);
+ }
+ else
+ *c += e - s + 1;
+
+ return rc;
+}
+
+/* Check if node itself can be removed and remove node from IOMMU. */
+static int remove_node_resources(struct dt_device_node *device_node)
+{
+ int rc = 0;
+ unsigned int len;
+ domid_t domid;
+
+ domid = dt_device_used_by(device_node);
+
+ dt_dprintk("Checking if node %s is used by any domain\n",
+ device_node->full_name);
+
+ /* Remove the node if only it's assigned to hardware domain or domain io. */
+ if ( domid != hardware_domain->domain_id && domid != DOMID_IO )
+ {
+ printk(XENLOG_ERR "Device %s is being used by domain %u. Removing nodes failed\n",
+ device_node->full_name, domid);
+ return -EINVAL;
+ }
+
+ /* Check if iommu property exists. */
+ if ( dt_get_property(device_node, "iommus", &len) )
+ {
+ if ( dt_device_is_protected(device_node) )
+ {
+ rc = iommu_remove_dt_device(device_node);
+ if ( rc < 0 )
+ return rc;
+ }
+ }
+
+ return rc;
+}
+
+/* Remove all descendants from IOMMU. */
+static int
+remove_descendant_nodes_resources(const struct dt_device_node *device_node)
+{
+ int rc = 0;
+ struct dt_device_node *child_node;
+
+ for ( child_node = device_node->child; child_node != NULL;
+ child_node = child_node->sibling )
+ {
+ if ( child_node->child )
+ {
+ rc = remove_descendant_nodes_resources(child_node);
+ if ( rc )
+ return rc;
+ }
+
+ rc = remove_node_resources(child_node);
+ if ( rc )
+ return rc;
+ }
+
+ return rc;
+}
+
+/* Remove nodes from dt_host. */
+static int remove_nodes(const struct overlay_track *tracker)
+{
+ int rc = 0;
+ struct dt_device_node *overlay_node;
+ unsigned int j;
+ struct domain *d = hardware_domain;
+
+ for ( j = 0; j < tracker->num_nodes; j++ )
+ {
+ overlay_node = (struct dt_device_node *)tracker->nodes_address[j];
+ if ( overlay_node == NULL )
+ {
+ printk(XENLOG_ERR "Device %s is not present in the tree. Removing nodes failed\n",
+ overlay_node->full_name);
+ return -EINVAL;
+ }
+
+ rc = remove_descendant_nodes_resources(overlay_node);
+ if ( rc )
+ return rc;
+
+ rc = remove_node_resources(overlay_node);
+ if ( rc )
+ return rc;
+
+ dt_dprintk("Removing node: %s\n", overlay_node->full_name);
+
+ write_lock(&dt_host_lock);
+
+ rc = dt_overlay_remove_node(overlay_node);
+ if ( rc )
+ {
+ write_unlock(&dt_host_lock);
+ return rc;
+ }
+
+ write_unlock(&dt_host_lock);
+ }
+
+ /* Remove IRQ access. */
+ if ( tracker->irq_ranges )
+ {
+ rc = rangeset_consume_ranges(tracker->irq_ranges, irq_remove_cb, d);
+ if ( rc )
+ return rc;
+ }
+
+ /* Remove mmio access. */
+ if ( tracker->iomem_ranges )
+ {
+ rc = rangeset_consume_ranges(tracker->iomem_ranges, iomem_remove_cb, d);
+ if ( rc )
+ return rc;
+ }
+
+ return rc;
+}
+
+/*
+ * First finds the device node to remove. Check if the device is being used by
+ * any dom and finally remove it from dt_host. IOMMU is already being taken care
+ * while destroying the domain.
+ */
+static long handle_remove_overlay_nodes(const void *overlay_fdt,
+ uint32_t overlay_fdt_size)
+{
+ int rc;
+ struct overlay_track *entry, *temp, *track;
+ bool found_entry = false;
+
+ rc = check_overlay_fdt(overlay_fdt, overlay_fdt_size);
+ if ( rc )
+ return rc;
+
+ spin_lock(&overlay_lock);
+
+ /*
+ * First check if dtbo is correct i.e. it should one of the dtbo which was
+ * used when dynamically adding the node.
+ * Limitation: Cases with same node names but different property are not
+ * supported currently. We are relying on user to provide the same dtbo
+ * as it was used when adding the nodes.
+ */
+ list_for_each_entry_safe( entry, temp, &overlay_tracker, entry )
+ {
+ if ( memcmp(entry->overlay_fdt, overlay_fdt, overlay_fdt_size) == 0 )
+ {
+ track = entry;
+ found_entry = true;
+ break;
+ }
+ }
+
+ if ( !found_entry )
+ {
+ rc = -EINVAL;
+
+ printk(XENLOG_ERR "Cannot find any matching tracker with input dtbo."
+ " Removing nodes is supported only for prior added dtbo.\n");
+ goto out;
+
+ }
+
+ rc = remove_nodes(entry);
+ if ( rc )
+ {
+ printk(XENLOG_ERR "Removing node failed\n");
+ goto out;
+ }
+
+ list_del(&entry->entry);
+
+ xfree(entry->dt_host_new);
+ xfree(entry->fdt);
+ xfree(entry->overlay_fdt);
+
+ xfree(entry->nodes_address);
+
+ rangeset_destroy(entry->irq_ranges);
+ rangeset_destroy(entry->iomem_ranges);
+
+ xfree(entry);
+
+ out:
+ spin_unlock(&overlay_lock);
+ return rc;
+}
+
+long dt_overlay_sysctl(struct xen_sysctl_dt_overlay *op)
+{
+ long ret;
+ void *overlay_fdt;
+
+ if ( op->overlay_op != XEN_SYSCTL_DT_OVERLAY_ADD &&
+ op->overlay_op != XEN_SYSCTL_DT_OVERLAY_REMOVE )
+ return -EOPNOTSUPP;
+
+ if ( op->overlay_fdt_size == 0 || op->overlay_fdt_size > KB(500) )
+ return -EINVAL;
+
+ if ( op->pad[0] || op->pad[1] || op->pad[2] )
+ return -EINVAL;
+
+ overlay_fdt = xmalloc_bytes(op->overlay_fdt_size);
+
+ if ( overlay_fdt == NULL )
+ return -ENOMEM;
+
+ ret = copy_from_guest(overlay_fdt, op->overlay_fdt, op->overlay_fdt_size);
+ if ( ret )
+ {
+ gprintk(XENLOG_ERR, "copy from guest failed\n");
+ xfree(overlay_fdt);
+
+ return -EFAULT;
+ }
+
+ if ( op->overlay_op == XEN_SYSCTL_DT_OVERLAY_REMOVE )
+ ret = handle_remove_overlay_nodes(overlay_fdt, op->overlay_fdt_size);
+
+ xfree(overlay_fdt);
+
+ return ret;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
projects / people / royger / xen.git / commitdiff