[RFC 14/19] xen/passthrough: dt: Add new domctl XEN_DOMCTL_assign_dt_device

[Julien Grall <julien.grall@linaro.org>]

A device node is described by a path. It will be used to retrieved the
node in the device tree and assign the related device to the domain.

Only device protected by an IOMMU can be assigned to a guest.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
---
 tools/libxc/xc_domain.c               |   29 +++++++++++++++++++++
 tools/libxc/xenctrl.h                 |    4 +++
 xen/drivers/passthrough/device_tree.c |   45 ++++++++++++++++++++++++++++++---
 xen/drivers/passthrough/iommu.c       |    7 +++++
 xen/include/public/domctl.h           |   10 ++++++++
 xen/include/xen/iommu.h               |    3 +++
 6 files changed, 95 insertions(+), 3 deletions(-)

diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index 7909536..ea8fc0d 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -1628,6 +1628,35 @@ int xc_deassign_device(
     return do_domctl(xch, &domctl);
 }
 
+int xc_assign_dt_device(
+    xc_interface *xch,
+    uint32_t domid,
+    char *path)
+{
+    int rc;
+    size_t size = strlen(path);
+    xen_domctl_assign_dt_device_t *assign_dt_device;
+    DECLARE_DOMCTL;
+    DECLARE_HYPERCALL_BOUNCE(path, size, XC_HYPERCALL_BUFFER_BOUNCE_IN);
+
+    if ( xc_hypercall_bounce_pre(xch, path) )
+        return -1;
+
+    domctl.cmd = XEN_DOMCTL_assign_dt_device;
+    domctl.domain = (domid_t)domid;
+
+    assign_dt_device = &domctl.u.assign_dt_device;
+
+    assign_dt_device->size = size;
+    set_xen_guest_handle(assign_dt_device->path, path);
+
+    rc = do_domctl(xch, &domctl);
+
+    xc_hypercall_bounce_post(xch, path);
+
+    return rc;
+}
+
 int xc_domain_update_msi_irq(
     xc_interface *xch,
     uint32_t domid,
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 5ad2d65..07dcadc 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -2010,6 +2010,10 @@ int xc_deassign_device(xc_interface *xch,
                      uint32_t domid,
                      uint32_t machine_bdf);
 
+int xc_assign_dt_device(xc_interface *xch,
+                        uint32_t domid,
+                        char *path);
+
 int xc_domain_memory_mapping(xc_interface *xch,
                              uint32_t domid,
                              unsigned long first_gfn,
diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
index 8a4bc69..9df4343 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -1,9 +1,6 @@
 /*
  * 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.
  *
@@ -20,6 +17,7 @@
 
 #include <xen/lib.h>
 #include <xen/sched.h>
+#include <xen/guest_access.h>
 #include <xen/iommu.h>
 #include <xen/device_tree.h>
 
@@ -111,3 +109,44 @@ void iommu_dt_domain_destroy(struct domain *d)
                     dt_node_full_name(dev), d->domain_id);
     }
 }
+
+int iommu_do_dt_domctl(struct xen_domctl *domctl, struct domain *d,
+                       XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
+{
+    int ret;
+
+    /* TODO: How to deal with XSM? */
+
+    switch ( domctl->cmd )
+    {
+    case XEN_DOMCTL_assign_dt_device:
+    {
+        struct dt_device_node *dev;
+
+
+        /* TODO: Do we need to check is_dying? Mostly to protect against
+         * hypercall trying to passthrough a device while we are
+         * dying.
+         */
+
+        ret = dt_find_node_by_gpath(domctl->u.assign_dt_device.path,
+                                    domctl->u.assign_dt_device.size,
+                                    &dev);
+        if ( ret )
+            break;
+
+        ret = iommu_assign_dt_device(d, dev);
+
+        if ( ret )
+            printk(XENLOG_G_ERR "XEN_DOMCTL_assign_dt_device: assign \"%s\""
+                   " to dom%u failed (%d)\n",
+                   dt_node_full_name(dev), d->domain_id, ret);
+    }
+    break;
+    default:
+        ret = -ENOSYS;
+        break;
+    }
+
+    return ret;
+}
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index d71ab03..8351814 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -343,6 +343,13 @@ int iommu_do_domctl(
     ret = iommu_do_pci_domctl(domctl, d, u_domctl);
 #endif
 
+    if ( ret != -ENOSYS )
+        return ret;
+
+#ifdef HAS_DEVICE_TREE
+    ret = iommu_do_dt_domctl(domctl, d, u_domctl);
+#endif
+
     return ret;
 }
 
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 5b11bbf..66806d2 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -936,6 +936,14 @@ typedef struct xen_domctl_vcpu_msrs xen_domctl_vcpu_msrs_t;
 DEFINE_XEN_GUEST_HANDLE(xen_domctl_vcpu_msrs_t);
 #endif
 
+/* Device Tree: Assign a non-PCI device to a guest */
+struct xen_domctl_assign_dt_device {
+    uint32_t size; /* IN: Length of the path */
+    XEN_GUEST_HANDLE_64(char) path; /* IN: path to the device tree node */
+};
+typedef struct xen_domctl_assign_dt_device xen_domctl_assign_dt_device_t;
+DEFINE_XEN_GUEST_HANDLE(xen_domctl_assign_dt_device_t);
+
 struct xen_domctl {
     uint32_t cmd;
 #define XEN_DOMCTL_createdomain                   1
@@ -1008,6 +1016,7 @@ struct xen_domctl {
 #define XEN_DOMCTL_cacheflush                    71
 #define XEN_DOMCTL_get_vcpu_msrs                 72
 #define XEN_DOMCTL_set_vcpu_msrs                 73
+#define XEN_DOMCTL_assign_dt_device              74
 #define XEN_DOMCTL_gdbsx_guestmemio            1000
 #define XEN_DOMCTL_gdbsx_pausevcpu             1001
 #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
@@ -1044,6 +1053,7 @@ struct xen_domctl {
         struct xen_domctl_sendtrigger       sendtrigger;
         struct xen_domctl_get_device_group  get_device_group;
         struct xen_domctl_assign_device     assign_device;
+        struct xen_domctl_assign_dt_device  assign_dt_device;
         struct xen_domctl_bind_pt_irq       bind_pt_irq;
         struct xen_domctl_memory_mapping    memory_mapping;
         struct xen_domctl_ioport_mapping    ioport_mapping;
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 9b2af51..833baca 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -118,6 +118,9 @@ 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);
 
+int iommu_do_dt_domctl(struct xen_domctl *, struct domain *,
+                       XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
+
 #endif /* HAS_DEVICE_TREE */
 
 struct page_info;
-- 
1.7.10.4