intel-iommu: Add Kconfig option to exclude iGPU by default

Bug-Debian: https://bugs.debian.org/935270
Bug-Kali: https://bugs.kali.org/view.php?id=5644

There is still laptop firmware that touches the integrated GPU behind
the operating system's back, and doesn't say so in the RMRR table.
Enabling the IOMMU for all devices causes breakage.

Replace CONFIG_INTEL_IOMMU_DEFAULT_ON with a 3-way choice
corresponding to "on", "off", and "on,intgpu_off".

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Topic features/x86
Gbp-Pq: Name intel-iommu-add-kconfig-option-to-exclude-igpu-by-default.patch

diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig
index f52fb39c968eb1e7b38ce808cade3a0da6b32f0c..8255277aaabe8a1ce819401340b82eb6150f5c41 100644 (file)
--- a/drivers/iommu/intel/Kconfig
+++ b/drivers/iommu/intel/Kconfig
@@ -57,13 +57,24 @@ config INTEL_IOMMU_SVM
          to access DMA resources through process address space by
          means of a Process Address Space ID (PASID).
 
-config INTEL_IOMMU_DEFAULT_ON
-       bool "Enable Intel DMA Remapping Devices by default"
-       default y
+choice
+       prompt "Default state of Intel DMA Remapping Devices"
+       default INTEL_IOMMU_DEFAULT_ON
        help
-         Selecting this option will enable a DMAR device at boot time if
-         one is found. If this option is not selected, DMAR support can
-         be enabled by passing intel_iommu=on to the kernel.
+         Choose whether Intel DMA Remapping Devices should be enabled
+         by default. This can be overridden at boot time using the
+         intel_iommu= kernel parameter.
+
+config INTEL_IOMMU_DEFAULT_ON
+       bool "Enable"
+
+config INTEL_IOMMU_DEFAULT_ON_INTGPU_OFF
+       bool "Enable, excluding integrated GPU"
+
+config INTEL_IOMMU_DEFAULT_OFF
+       bool "Disable"
+
+endchoice
 
 config INTEL_IOMMU_FLOPPY_WA
        def_bool y

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 41e8dc522fcdbc4cbe210626c6845296206081de..5b37fed9dd16cb9a2813e075659942cd4cd462aa 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -214,13 +214,13 @@ static LIST_HEAD(dmar_satc_units);
 
 static void intel_iommu_domain_free(struct iommu_domain *domain);
 
-int dmar_disabled = !IS_ENABLED(CONFIG_INTEL_IOMMU_DEFAULT_ON);
+int dmar_disabled = IS_ENABLED(CONFIG_INTEL_IOMMU_DEFAULT_OFF);
 int intel_iommu_sm = IS_ENABLED(CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON);
 
 int intel_iommu_enabled = 0;
 EXPORT_SYMBOL_GPL(intel_iommu_enabled);
 
-static int dmar_map_intgpu = 1;
+static int dmar_map_intgpu = IS_ENABLED(CONFIG_INTEL_IOMMU_DEFAULT_ON);
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
 static int iommu_skip_te_disable;
@@ -259,6 +259,7 @@ static int __init intel_iommu_setup(char *str)
        while (*str) {
                if (!strncmp(str, "on", 2)) {
                        dmar_disabled = 0;
+                       dmar_map_intgpu = 1;
                        pr_info("IOMMU enabled\n");
                } else if (!strncmp(str, "off", 3)) {
                        dmar_disabled = 1;