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/Kconfig b/drivers/iommu/Kconfig
index 0b9d78a0f3aca9bdb1d06acf08249b8606f652fc..6a25db137a680c7155a915ea57608d51f6c0a6dc 100644 (file)
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -219,14 +219,28 @@ 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
-       def_bool y
-       prompt "Enable Intel DMA Remapping Devices by default"
-       depends on INTEL_IOMMU
+if INTEL_IOMMU
+
+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
+
+endif
 
 config INTEL_IOMMU_BROKEN_GFX_WA
        bool "Workaround broken graphics drivers (going away soon)"

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 981eb11020f9f97c44bdfd77103078477406bee7..ba1528614a5e81d6dfa09ea3fdff2961a22cd0bb 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -354,18 +354,14 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
                                            dma_addr_t iova);
 
-#ifdef CONFIG_INTEL_IOMMU_DEFAULT_ON
-int dmar_disabled = 0;
-#else
-int dmar_disabled = 1;
-#endif /*CONFIG_INTEL_IOMMU_DEFAULT_ON*/
+int dmar_disabled = IS_ENABLED(CONFIG_INTEL_IOMMU_DEFAULT_OFF);
 
 int intel_iommu_sm;
 int intel_iommu_enabled = 0;
 EXPORT_SYMBOL_GPL(intel_iommu_enabled);
 
 static int dmar_map_gfx = 1;
-static int dmar_map_intgpu = 1;
+static int dmar_map_intgpu = IS_ENABLED(CONFIG_INTEL_IOMMU_DEFAULT_ON);
 static int dmar_forcedac;
 static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
@@ -446,6 +442,7 @@ 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;