[Xen-devel] [PATCH v7b 5/8] xen/arm: assign devices to boot domains

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Scan the user provided dtb fragment at boot. For each device node, map
memory to guests, and route interrupts and setup the iommu.

The memory region to remap is specified by the "xen,reg" property.

The iommu is setup by passing the node of the device to assign on the
host device tree. The path is specified in the device tree fragment as
the "xen,path" string property.

The interrupts are remapped based on the information from the
corresponding node on the host device tree. Call
handle_device_interrupts to remap interrupts. Interrupts related device
tree properties are copied from the device tree fragment, same as all
the other properties.

Require both xen,reg and xen,path to be present, unless
xen,force-assign-without-iommu is also set. In that case, tolerate a
missing xen,path, also tolerate iommu setup failure for the passthrough
device.

Also set add the new flag XEN_DOMCTL_CDF_iommu so that dom0less domU
can use the IOMMU if a partial dtb is specified.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
---
Changes in v7:
- improve in-code comment
- code style
- return 1 instead of ENOENT
- introduce "xen,force-assign-without-iommu"
- require both "xen,reg" and "xen,path" unless
  "xen,force-assign-without-iommu"

Changes in v6:
- turn dprintks into printks
- return error on page alignment check failure
- set XEN_DOMCTL_CDF_iommu if partial dtb is specified

Changes in v5:
- use local variable for name
- use map_regions_p2mt
- add warning for not page aligned addresses/sizes
- introduce handle_passthrough_prop

Changes in v4:
- use unsigned
- improve commit message
- code style
- use dt_prop_cmp
- use device_tree_get_reg
- don't copy over xen,reg and xen,path
- don't create special interrupt properties for domU: copy them from the
  fragment
- in-code comment

Changes in v3:
- improve commit message
- remove superfluous cast
- merge code with the copy code
- add interrup-parent
- demove depth > 2 check
- reuse code from handle_device_interrupts
- copy interrupts from host dt

Changes in v2:
- rename "path" to "xen,path"
- grammar fix
- use gaddr_to_gfn and maddr_to_mfn
- remove depth <= 2 limitation in scanning the dtb fragment
- introduce and parse xen,reg
- code style
- support more than one interrupt per device
- specify only the GIC is supported
---
 xen/arch/arm/domain_build.c | 133 ++++++++++++++++++++++++++++++++++--
 1 file changed, 129 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 84b65b8f25..47f9bb31df 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1714,6 +1714,88 @@ static int __init make_vpl011_uart_node(struct 
kernel_info *kinfo)
 }
 #endif
 
+/*
+ * Scan device tree properties for passthrough specific information.
+ * Returns < 0 on error
+ *         0 on success
+ */
+static int __init handle_passthrough_prop(struct kernel_info *kinfo,
+                                          const struct fdt_property *xen_reg,
+                                          const struct fdt_property *xen_path,
+                                          bool xen_force,
+                                          uint32_t address_cells, uint32_t 
size_cells)
+{
+    const __be32 *cell;
+    unsigned int i, len;
+    struct dt_device_node *node;
+    int res;
+    paddr_t mstart, size, gstart;
+
+    /* xen,reg specifies where to map the MMIO region */
+    cell = (const __be32 *)xen_reg->data;
+    len = fdt32_to_cpu(xen_reg->len) /
+          ((address_cells * 2 + size_cells) * sizeof(uint32_t));
+
+    for ( i = 0; i < len; i++ )
+    {
+        device_tree_get_reg(&cell, address_cells, size_cells,
+                            &mstart, &size);
+        gstart = dt_next_cell(address_cells, &cell);
+
+        if ( gstart & ~PAGE_MASK || mstart & ~PAGE_MASK || size & ~PAGE_MASK )
+        {
+            printk(XENLOG_ERR
+                    "DomU passthrough config has not page aligned 
addresses/sizes\n");
+            return -EINVAL;
+        }
+
+        res = map_regions_p2mt(kinfo->d,
+                               gaddr_to_gfn(gstart),
+                               PFN_DOWN(size),
+                               maddr_to_mfn(mstart),
+                               p2m_mmio_direct_dev);
+        if ( res < 0 )
+        {
+            printk(XENLOG_ERR
+                   "Failed to map %"PRIpaddr" to the guest at%"PRIpaddr"\n",
+                   mstart, gstart);
+            return -EFAULT;
+        }
+    }
+
+    /*
+     * If xen_force, we let the user assign a MMIO region with no
+     * associated path.
+     */
+    if ( xen_path == NULL )
+        return xen_force ? 0 : -EINVAL;
+
+    /*
+     * xen,path specifies the corresponding node in the host DT.
+     * Both interrupt mappings and IOMMU settings are based on it,
+     * as they are done based on the corresponding host DT node.
+     */
+    node = dt_find_node_by_path(xen_path->data);
+    if ( node == NULL )
+    {
+        printk(XENLOG_ERR "Couldn't find node %s in host_dt!\n",
+               (char *)xen_path->data);
+        return -EINVAL;
+    }
+
+    res = handle_device_interrupts(kinfo->d, node, true);
+    if ( res < 0 )
+        return res;
+
+    /* If xen_force, we ignore IOMMU failures. */
+    res = iommu_add_dt_device(node);
+    if ( res < 0 )
+        return xen_force ? 0 : -EINVAL;
+
+    res = iommu_assign_dt_device(kinfo->d, node);
+    return res;
+}
+
 static int __init handle_prop_pfdt(struct kernel_info *kinfo,
                                    const void *pfdt, int nodeoff,
                                    uint32_t address_cells, uint32_t size_cells,
@@ -1721,7 +1803,9 @@ static int __init handle_prop_pfdt(struct kernel_info 
*kinfo,
 {
     void *fdt = kinfo->fdt;
     int propoff, nameoff, res;
-    const struct fdt_property *prop;
+    const struct fdt_property *prop, *xen_reg = NULL, *xen_path = NULL;
+    const char *name;
+    bool found, xen_force = false;
 
     for ( propoff = fdt_first_property_offset(pfdt, nodeoff);
           propoff >= 0;
@@ -1730,10 +1814,48 @@ static int __init handle_prop_pfdt(struct kernel_info 
*kinfo,
         if ( !(prop = fdt_get_property_by_offset(pfdt, propoff, NULL)) )
             return -FDT_ERR_INTERNAL;
 
+        found = false;
         nameoff = fdt32_to_cpu(prop->nameoff);
-        res = fdt_property(fdt, fdt_string(pfdt, nameoff),
-                           prop->data, fdt32_to_cpu(prop->len));
-        if ( res )
+        name = fdt_string(pfdt, nameoff);
+
+        if ( scan_passthrough_prop )
+        {
+            if ( dt_prop_cmp("xen,reg", name) == 0 )
+            {
+                xen_reg = prop;
+                found = true;
+            }
+            else if ( dt_prop_cmp("xen,path", name) == 0 )
+            {
+                xen_path = prop;
+                found = true;
+            }
+            else if ( dt_prop_cmp("xen,force-assign-without-iommu",
+                      name) == 0 )
+            {
+                xen_force = true;
+                found = true;
+            }
+        }
+
+        /* Copy all other properties */
+        if ( !found )
+        {
+            res = fdt_property(fdt, name, prop->data, fdt32_to_cpu(prop->len));
+            if ( res )
+                return res;
+        }
+    }
+
+    /*
+     * Only handle passthrough properties if both xen,reg and xen,path
+     * are present, or if xen,force-assign-without-iommu is specified.
+     */
+    if ( xen_reg != NULL && (xen_path != NULL || xen_force) )
+    {
+        res = handle_passthrough_prop(kinfo, xen_reg, xen_path, xen_force,
+                                      address_cells, size_cells);
+        if ( res < 0 )
             return res;
     }
 
@@ -2291,6 +2413,9 @@ void __init create_domUs(void)
             panic("Missing property 'cpus' for domain %s\n",
                   dt_node_name(node));
 
+        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") )
+            d_cfg.flags |= XEN_DOMCTL_CDF_iommu;
+
         d = domain_create(++max_init_domid, &d_cfg, false);
         if ( IS_ERR(d) )
             panic("Error creating domain %s\n", dt_node_name(node));
-- 
2.17.1


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