linux/pc: enable IOMMU config for intel fb

to apply scanout scratch page GTT workaround

drivers/gpu/drm/i915/gt/intel_ggtt.c
 -> gen8_gmch_probe() -> intel_scanout_needs_vtd_wa(i915)

Fixes #4659

repos/pc/src/drivers/framebuffer/intel/pc/dummies.c

@@ -577,3 +577,16 @@ int pci_bus_write_config_byte(struct pci_bus *bus, unsigned int devfn,
 {
 	lx_emul_trace_and_stop(__func__);
 }
+
+
+int pci_enable_msi(struct pci_dev *dev)
+{
+	lx_emul_trace(__func__);
+	return -ENOSYS;
+}
+
+
+void pci_disable_msi(struct pci_dev *dev)
+{
+	lx_emul_trace(__func__);
+}

repos/pc/src/drivers/framebuffer/intel/pc/lx_emul.c

@@ -17,6 +17,7 @@
 
 #include <linux/dma-fence.h>
 #include <linux/fs.h>
+#include <linux/intel-iommu.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/proc_fs.h>
@@ -31,7 +32,8 @@ struct dma_fence_ops const i915_fence_ops;
 pteval_t __default_kernel_pte_mask __read_mostly = ~0;
 
 
-int acpi_disabled = 0;
+int acpi_disabled          = 0;
+int intel_iommu_gfx_mapped = 0;
 
 
 void intel_wopcm_init_early(struct intel_wopcm * wopcm)
@@ -217,6 +219,15 @@ void intel_gt_init_early(struct intel_gt * gt, struct drm_i915_private * i915)
 
 	/* disable panel self refresh (required for FUJITSU S937/S938) */
 	i915->params.enable_psr = 0;
+
+	/*
+	 * Tells driver that IOMMU, e.g. VT-d, is on, so that scratch page
+	 * workaround is applied by Intel display driver:
+	 *
+	 * drivers/gpu/drm/i915/gt/intel_ggtt.c
+	 *  -> gen8_gmch_probe() -> intel_scanout_needs_vtd_wa(i915)
+	 */
+	intel_iommu_gfx_mapped = 1;
 }
 
 

repos/pc/src/drivers/usb_host/pc/dep.list

@@ -29,6 +29,7 @@ drivers/usb/host/xhci-ext-caps.h
 drivers/usb/host/xhci-pci.h
 drivers/usb/host/xhci-trace.h
 drivers/usb/host/xhci.h
+include/asm-generic/dma-mapping.h
 include/asm-generic/export.h
 include/linux/bcd.h
 include/linux/extcon.h

repos/pc/src/drivers/usb_host/pc/lx_emul.c

@@ -85,3 +85,26 @@ int pci_write_config_word(const struct pci_dev * dev,int where,u16 val)
 	}
 	lx_emul_trace_and_stop(__func__);
 }
+
+
+int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
+                                   unsigned int max_vecs, unsigned int flags,
+                                   struct irq_affinity *aff_desc)
+{
+	if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1 && dev->irq)
+		return 1;
+	return -ENOSPC;
+}
+
+
+int pci_irq_vector(struct pci_dev *dev, unsigned int nr)
+{
+	if (WARN_ON_ONCE(nr > 0))
+		return -EINVAL;
+	return dev->irq;
+}
+
+
+void pci_free_irq_vectors(struct pci_dev *dev)
+{
+}

repos/pc/src/lib/wifi/dummies.c

@@ -339,3 +339,18 @@ void synchronize_rcu_expedited(void)
 {
 	lx_emul_trace(__func__);
 }
+
+
+int pci_enable_msi(struct pci_dev *dev)
+{
+	lx_emul_trace(__func__);
+	return -ENOSYS;
+}
+
+
+int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
+                          int minvec, int maxvec)
+{
+	lx_emul_trace(__func__);
+	return -ENOSYS;
+}

repos/pc/src/pc_linux/target.inc

@@ -15,7 +15,10 @@ LX_ENABLE += BINFMT_ELF BINFMT_SCRIPT BLK_DEV_INITRD
 LX_ENABLE += SERIAL_8250 SERIAL_8250_CONSOLE
 
 # PCI support
-LX_ENABLE += PCI
+LX_ENABLE += PCI PCI_MSI
+
+# IOMMU support (used by Intel fb to apply scanout scratch page workaround)
+LX_ENABLE += IOMMU_SUPPORT INTEL_IOMMU
 
 # ACPI support
 LX_ENABLE += ACPI