On 2014/9/12 10:10, Jiang Liu wrote:
> 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.
Reviewed-by: Yijing Wang <wangyijing@xxxxxxxxxx>
>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
> ---
> 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 e77b5d3f2f5c..df2c2591c1a6 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1926,21 +1926,48 @@ 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;
>
--
Thanks!
Yijing
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