x86/amd-iommu: Add amd_iommu=off command line option
This patch adds a command line option to tell the AMD IOMMU
driver to not initialize any IOMMU it finds.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 839b21b..0c6c560 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -324,6 +324,8 @@
they are unmapped. Otherwise they are
flushed before they will be reused, which
is a lot of faster
+ off - do not initialize any AMD IOMMU found in
+ the system
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 6360abf..3bacb4d 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -120,6 +120,7 @@
bool amd_iommu_dump;
static int __initdata amd_iommu_detected;
+static bool __initdata amd_iommu_disabled;
u16 amd_iommu_last_bdf; /* largest PCI device id we have
to handle */
@@ -1372,6 +1373,9 @@
if (no_iommu || (iommu_detected && !gart_iommu_aperture))
return;
+ if (amd_iommu_disabled)
+ return;
+
if (acpi_table_parse("IVRS", early_amd_iommu_detect) == 0) {
iommu_detected = 1;
amd_iommu_detected = 1;
@@ -1401,6 +1405,8 @@
for (; *str; ++str) {
if (strncmp(str, "fullflush", 9) == 0)
amd_iommu_unmap_flush = true;
+ if (strncmp(str, "off", 3) == 0)
+ amd_iommu_disabled = true;
}
return 1;