iommu/vt-d: Search for ACPI _DSM method for DMAR hotplug

According to Intel VT-d specification, _DSM method to support DMAR
hotplug should exist directly under corresponding ACPI object
representing PCI host bridge. But some BIOSes doesn't conform to
this, so search for _DSM method in the subtree starting from the
ACPI object representing the PCI host bridge.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Reviewed-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 0bd536d..9847613 100644 (file)
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1942,21 +1942,48 @@ static int dmar_hotplug_remove(acpi_handle handle)
        return ret;
 }
 
+static acpi_status dmar_get_dsm_handle(acpi_handle handle, u32 lvl,
+                                      void *context, void **retval)
+{
+       acpi_handle *phdl = retval;
+
+       if (dmar_detect_dsm(handle, DMAR_DSM_FUNC_DRHD)) {
+               *phdl = handle;
+               return AE_CTRL_TERMINATE;
+       }
+
+       return AE_OK;
+}
+
 static int dmar_device_hotplug(acpi_handle handle, bool insert)
 {
        int ret;
+       acpi_handle tmp = NULL;
+       acpi_status status;
 
        if (!dmar_in_use())
                return 0;
 
-       if (!dmar_detect_dsm(handle, DMAR_DSM_FUNC_DRHD))
+       if (dmar_detect_dsm(handle, DMAR_DSM_FUNC_DRHD)) {
+               tmp = handle;
+       } else {
+               status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle,
+                                            ACPI_UINT32_MAX,
+                                            dmar_get_dsm_handle,
+                                            NULL, NULL, &tmp);
+               if (ACPI_FAILURE(status)) {
+                       pr_warn("Failed to locate _DSM method.\n");
+                       return -ENXIO;
+               }
+       }
+       if (tmp == NULL)
                return 0;
 
        down_write(&dmar_global_lock);
        if (insert)
-               ret = dmar_hotplug_insert(handle);
+               ret = dmar_hotplug_insert(tmp);
        else
-               ret = dmar_hotplug_remove(handle);
+               ret = dmar_hotplug_remove(tmp);
        up_write(&dmar_global_lock);
 
        return ret;