xen/passthrough: iommu: Basic support of device tree assignment

Add IOMMU helpers to support device tree assignment/deassignment. This patch
introduces 2 new fields in the dt_device_node:
    - is_protected: Does the device is protected by an IOMMU
    - domain_list: Pointer to the next device assigned to the same
    domain

This commit contains only support to protected a device with DOM0.
Device passthrough to another guest won't work out-of-box.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Xiantao Zhang <xiantao.zhang@intel.com>

xen/common/device_tree.c

@@ -1695,6 +1695,10 @@ static unsigned long __init unflatten_dt_node(const void *fdt,
         np->full_name = ((char *)np) + sizeof(struct dt_device_node);
         /* By default dom0 owns the device */
         np->used_by = 0;
+        /* By default the device is not protected */
+        np->is_protected = false;
+        INIT_LIST_HEAD(&np->domain_list);
+
         if ( new_format )
         {
             char *fn = np->full_name;

xen/drivers/passthrough/Makefile

@@ -5,3 +5,4 @@ subdir-$(x86_64) += x86
 obj-y += iommu.o
 obj-$(x86) += io.o
 obj-$(HAS_PCI) += pci.o
+obj-$(HAS_DEVICE_TREE) += device_tree.o

xen/drivers/passthrough/device_tree.c

+/*
+ * Code to passthrough a device tree node to a guest
+ *
+ * TODO: This contains only the necessary code to protected device passed to
+ * dom0. It will need some updates when device passthrough will is added.
+ *
+ * Julien Grall <julien.grall@linaro.org>
+ * Copyright (c) 2014 Linaro Limited.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <xen/lib.h>
+#include <xen/sched.h>
+#include <xen/iommu.h>
+#include <xen/device_tree.h>
+
+static spinlock_t dtdevs_lock = SPIN_LOCK_UNLOCKED;
+
+int iommu_assign_dt_device(struct domain *d, struct dt_device_node *dev)
+{
+    int rc = -EBUSY;
+    struct hvm_iommu *hd = domain_hvm_iommu(d);
+
+    if ( !iommu_enabled || !hd->platform_ops )
+        return -EINVAL;
+
+    if ( !dt_device_is_protected(dev) )
+        return -EINVAL;
+
+    spin_lock(&dtdevs_lock);
+
+    if ( !list_empty(&dev->domain_list) )
+        goto fail;
+
+    rc = hd->platform_ops->assign_dt_device(d, dev);
+
+    if ( rc )
+        goto fail;
+
+    list_add(&dev->domain_list, &hd->dt_devices);
+    dt_device_set_used_by(dev, d->domain_id);
+
+fail:
+    spin_unlock(&dtdevs_lock);
+
+    return rc;
+}
+
+int iommu_deassign_dt_device(struct domain *d, struct dt_device_node *dev)
+{
+    struct hvm_iommu *hd = domain_hvm_iommu(d);
+    int rc;
+
+    if ( !iommu_enabled || !hd->platform_ops )
+        return -EINVAL;
+
+    if ( !dt_device_is_protected(dev) )
+        return -EINVAL;
+
+    spin_lock(&dtdevs_lock);
+
+    rc = hd->platform_ops->reassign_dt_device(d, hardware_domain, dev);
+    if ( rc )
+        goto fail;
+
+    list_del(&dev->domain_list);
+
+    dt_device_set_used_by(dev, hardware_domain->domain_id);
+    list_add(&dev->domain_list, &domain_hvm_iommu(hardware_domain)->dt_devices);
+
+fail:
+    spin_unlock(&dtdevs_lock);
+
+    return rc;
+}
+
+int iommu_dt_domain_init(struct domain *d)
+{
+    struct hvm_iommu *hd = domain_hvm_iommu(d);
+
+    INIT_LIST_HEAD(&hd->dt_devices);
+
+    return 0;
+}
+
+void iommu_dt_domain_destroy(struct domain *d)
+{
+    struct hvm_iommu *hd = domain_hvm_iommu(d);
+    struct dt_device_node *dev, *_dev;
+    int rc;
+
+    list_for_each_entry_safe(dev, _dev, &hd->dt_devices, domain_list)
+    {
+        rc = iommu_deassign_dt_device(d, dev);
+        if ( rc )
+            dprintk(XENLOG_ERR, "Failed to deassign %s in domain %u\n",
+                    dt_node_full_name(dev), d->domain_id);
+    }
+}

xen/include/xen/device_tree.h

@@ -16,6 +16,7 @@
 #include <xen/string.h>
 #include <xen/types.h>
 #include <xen/stdbool.h>
+#include <xen/list.h>
 
 #define DEVICE_TREE_MAX_DEPTH 16
 
@@ -111,6 +112,9 @@ struct dt_device_node {
     struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */
     struct dt_device_node *allnext;
 
+    /* IOMMU specific fields */
+    bool is_protected;
+    struct list_head domain_list;
 };
 
 #define MAX_PHANDLE_ARGS 16
@@ -326,6 +330,16 @@ static inline domid_t dt_device_used_by(const struct dt_device_node *device)
     return device->used_by;
 }
 
+static inline void dt_device_set_protected(struct dt_device_node *device)
+{
+    device->is_protected = true;
+}
+
+static inline bool dt_device_is_protected(const struct dt_device_node *device)
+{
+    return device->is_protected;
+}
+
 static inline bool_t dt_property_name_is_equal(const struct dt_property *pp,
                                                const char *name)
 {

xen/include/xen/hvm/iommu.h

@@ -21,6 +21,7 @@
 #define __XEN_HVM_IOMMU_H__
 
 #include <xen/iommu.h>
+#include <xen/list.h>
 #include <asm/hvm/iommu.h>
 
 struct hvm_iommu {
@@ -28,6 +29,11 @@ struct hvm_iommu {
 
     /* iommu_ops */
     const struct iommu_ops *platform_ops;
+
+#ifdef HAS_DEVICE_TREE
+    /* List of DT devices assigned to this domain */
+    struct list_head dt_devices;
+#endif
 };
 
 #endif /* __XEN_HVM_IOMMU_H__ */

xen/include/xen/iommu.h

@@ -90,6 +90,16 @@ void iommu_read_msi_from_ire(struct msi_desc *msi_desc, struct msi_msg *msg);
 #define PT_IRQ_TIME_OUT MILLISECS(8)
 #endif /* HAS_PCI */
 
+#ifdef HAS_DEVICE_TREE
+#include <xen/device_tree.h>
+
+int iommu_assign_dt_device(struct domain *d, struct dt_device_node *dev);
+int iommu_deassign_dt_device(struct domain *d, struct dt_device_node *dev);
+int iommu_dt_domain_init(struct domain *d);
+void iommu_dt_domain_destroy(struct domain *d);
+
+#endif /* HAS_DEVICE_TREE */
+
 struct page_info;
 
 struct iommu_ops {
@@ -106,6 +116,12 @@ struct iommu_ops {
     int (*update_ire_from_msi)(struct msi_desc *msi_desc, struct msi_msg *msg);
     void (*read_msi_from_ire)(struct msi_desc *msi_desc, struct msi_msg *msg);
 #endif /* HAS_PCI */
+#ifdef HAS_DEVICE_TREE
+    int (*assign_dt_device)(struct domain *d, const struct dt_device_node *dev);
+    int (*reassign_dt_device)(struct domain *s, struct domain *t,
+                              const struct dt_device_node *dev);
+#endif
+
     void (*teardown)(struct domain *d);
     int (*map_page)(struct domain *d, unsigned long gfn, unsigned long mfn,
                     unsigned int flags);