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 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -324,6 +324,8 @@ and is between 256 and 4096 characters. It is defined in the file
                                    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 (file)
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -120,6 +120,7 @@ struct ivmd_header {
 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 @@ void __init amd_iommu_detect(void)
        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 @@ static int __init parse_amd_iommu_options(char *str)
        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;