[Patch Part3 V4 17/21] iommu/vt-d: Search for ACPI _DSM method for DMAR hotplug

Jiang Liu
2014-07-11T06:20:00Z

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>
---
drivers/iommu/dmar.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 9d8f5c82b717..cc1d19c33486 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1927,21 +1927,48 @@ static int dmar_hotplug_remove(acpi_handle handle)
return ret;
}

-static int dmar_device_hotplug(acpi_handle handle, bool insert)
+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;
+}
+
+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;
--
1.7.10.4