[RFC PATCH 41/42] HAX drm/i915: add the fake lmem region

[Matthew Auld <matthew.auld@intel.com>]

Intended for upstream testing so that we can still exercise the LMEM
plumbing and !HAS_MAPPABLE_APERTURE paths. Smoke tested on Skull Canyon
device. This works by allocating an intel_memory_region for a reserved
portion of system memory, which we treat like LMEM. For the LMEMBAR we
steal the aperture and 1:1 it map to the stolen region.

To enable simply set i915_fake_lmem_start= on the kernel cmdline with the
start of reserved region(see memmap=). The size of the region we can
use is determined by the size of the mappable aperture, so the size of
reserved region should be >= mappable_end.

eg. memmap=2G$16G i915_fake_lmem_start=0x400000000

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
---
 arch/x86/kernel/early-quirks.c             | 26 ++++++++
 drivers/gpu/drm/i915/i915_drv.c            |  7 +++
 drivers/gpu/drm/i915/i915_gem_gtt.c        |  3 +
 drivers/gpu/drm/i915/intel_memory_region.h |  4 ++
 drivers/gpu/drm/i915/intel_region_lmem.c   | 73 ++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_region_lmem.h   |  3 +
 include/drm/i915_drm.h                     |  3 +
 7 files changed, 119 insertions(+)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 50d5848bf22e..bdc99d6bfa26 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -600,6 +600,32 @@ static void __init intel_graphics_quirks(int num, int slot, int func)
 	}
 }
 
+struct resource intel_graphics_fake_lmem_res __ro_after_init = DEFINE_RES_MEM(0, 0);
+EXPORT_SYMBOL(intel_graphics_fake_lmem_res);
+
+static int __init early_i915_fake_lmem_init(char *s)
+{
+	u64 start;
+	int ret;
+
+	if (*s == '=')
+		s++;
+
+	ret = kstrtoull(s, 16, &start);
+	if (ret)
+		return ret;
+
+	intel_graphics_fake_lmem_res.start = start;
+	intel_graphics_fake_lmem_res.end = SZ_2G; /* Placeholder; depends on aperture size */
+
+	printk(KERN_INFO "Intel graphics fake LMEM starts at %pa\n",
+	       &intel_graphics_fake_lmem_res.start);
+
+	return 0;
+}
+
+early_param("i915_fake_lmem_start", early_i915_fake_lmem_init);
+
 static void __init force_disable_hpet(int num, int slot, int func)
 {
 #ifdef CONFIG_HPET_TIMER
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 08a4286b70c6..54e24fa075c9 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1732,6 +1732,13 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!i915_modparams.nuclear_pageflip && match_info->gen < 5)
 		dev_priv->drm.driver_features &= ~DRIVER_ATOMIC;
 
+	/* Check if we need fake LMEM */
+	if (INTEL_GEN(dev_priv) >= 9 && intel_graphics_fake_lmem_res.start) {
+		mkwrite_device_info(dev_priv)->memory_regions =
+			REGION_SMEM | REGION_LMEM;
+		GEM_BUG_ON(!HAS_LMEM(dev_priv));
+	}
+
 	ret = pci_enable_device(pdev);
 	if (ret)
 		goto out_fini;
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index f5d595c700f4..4101992b65f3 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2832,6 +2832,9 @@ static int i915_gem_init_memory_regions(struct drm_i915_private *i915)
 		case INTEL_STOLEN:
 			mem = i915_gem_setup_stolen(i915);
 			break;
+		case INTEL_LMEM:
+			mem = i915_gem_setup_fake_lmem(i915);
+			break;
 		}
 
 		if (IS_ERR(mem)) {
diff --git a/drivers/gpu/drm/i915/intel_memory_region.h b/drivers/gpu/drm/i915/intel_memory_region.h
index 7754989ad165..ebc46024a376 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.h
+++ b/drivers/gpu/drm/i915/intel_memory_region.h
@@ -28,6 +28,7 @@
 #include <linux/ioport.h>
 #include <linux/mutex.h>
 #include <linux/io-mapping.h>
+#include <drm/drm_mm.h>
 
 #include "i915_gem_buddy.h"
 
@@ -90,6 +91,9 @@ struct intel_memory_region {
 	struct io_mapping iomap;
 	struct resource region;
 
+	/* For faking for lmem */
+	struct drm_mm_node fake_mappable;
+
 	struct i915_gem_buddy_mm mm;
 	struct mutex mm_lock;
 
diff --git a/drivers/gpu/drm/i915/intel_region_lmem.c b/drivers/gpu/drm/i915/intel_region_lmem.c
index 10dfcf961c4b..a5a7386ff255 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/intel_region_lmem.c
@@ -233,9 +233,41 @@ region_lmem_object_create(struct intel_memory_region *mem,
 	return obj;
 }
 
+static int i915_gem_init_fake_lmem_bar(struct intel_memory_region *mem)
+{
+	struct drm_i915_private *i915 = mem->i915;
+	struct i915_ggtt *ggtt = &i915->ggtt;
+	unsigned long n;
+	int ret;
+
+	mem->fake_mappable.start = 0;
+	mem->fake_mappable.size = resource_size(&mem->region);
+	mem->fake_mappable.color = I915_COLOR_UNEVICTABLE;
+
+	ret = drm_mm_reserve_node(&ggtt->vm.mm, &mem->fake_mappable);
+	if (ret)
+		return ret;
+
+	/* 1:1 map the mappable aperture to our reserved region */
+	for (n = 0; n < mem->fake_mappable.size >> PAGE_SHIFT; ++n) {
+		ggtt->vm.insert_page(&ggtt->vm,
+				     mem->region.start + (n << PAGE_SHIFT),
+				     n << PAGE_SHIFT, I915_CACHE_NONE, 0);
+	}
+
+	return 0;
+}
+
+static void i915_gem_relase_fake_lmem_bar(struct intel_memory_region *mem)
+{
+	if (drm_mm_node_allocated(&mem->fake_mappable))
+		drm_mm_remove_node(&mem->fake_mappable);
+}
+
 static void
 region_lmem_release(struct intel_memory_region *mem)
 {
+	i915_gem_relase_fake_lmem_bar(mem);
 	io_mapping_fini(&mem->iomap);
 	i915_memory_region_release_buddy(mem);
 }
@@ -245,6 +277,11 @@ region_lmem_init(struct intel_memory_region *mem)
 {
 	int ret;
 
+	if (intel_graphics_fake_lmem_res.start) {
+		ret = i915_gem_init_fake_lmem_bar(mem);
+		GEM_BUG_ON(ret);
+	}
+
 	if (!io_mapping_init_wc(&mem->iomap,
 				mem->io_start,
 				resource_size(&mem->region)))
@@ -270,6 +307,7 @@ void __iomem *i915_gem_object_lmem_io_map_page(struct drm_i915_gem_object *obj,
 	resource_size_t offset;
 
 	offset = i915_gem_object_get_dma_address(obj, n);
+	offset -= intel_graphics_fake_lmem_res.start;
 
 	return io_mapping_map_atomic_wc(&obj->memory_region->iomap, offset);
 }
@@ -283,6 +321,7 @@ void __iomem *i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,
 	GEM_BUG_ON(!(obj->flags & I915_BO_ALLOC_CONTIGUOUS));
 
 	offset = i915_gem_object_get_dma_address(obj, n);
+	offset -= intel_graphics_fake_lmem_res.start;
 
 	return io_mapping_map_wc(&obj->memory_region->iomap, offset, size);
 }
@@ -294,6 +333,7 @@ unsigned long i915_gem_object_lmem_io_pfn(struct drm_i915_gem_object *obj,
 	resource_size_t offset;
 
 	offset = i915_gem_object_get_dma_address(obj, n);
+	offset -= intel_graphics_fake_lmem_res.start;
 
 	return (mem->io_start + offset) >> PAGE_SHIFT;
 }
@@ -313,3 +353,36 @@ i915_gem_object_create_lmem(struct drm_i915_private *i915,
 	return i915_gem_object_create_region(i915->regions[INTEL_MEMORY_LMEM],
 					     size, flags);
 }
+
+struct intel_memory_region *
+i915_gem_setup_fake_lmem(struct drm_i915_private *i915)
+{
+	struct pci_dev *pdev = i915->drm.pdev;
+	struct intel_memory_region *mem;
+	resource_size_t mappable_end;
+	resource_size_t io_start;
+	resource_size_t start;
+
+	GEM_BUG_ON(HAS_MAPPABLE_APERTURE(i915));
+	GEM_BUG_ON(!intel_graphics_fake_lmem_res.start);
+
+	/* Your mappable aperture belongs to me now! */
+	mappable_end = pci_resource_len(pdev, 2);
+	io_start = pci_resource_start(pdev, 2),
+	start = intel_graphics_fake_lmem_res.start;
+
+	mem = intel_memory_region_create(i915,
+					 start,
+					 mappable_end,
+					 I915_GTT_PAGE_SIZE_4K,
+					 io_start,
+					 &region_lmem_ops);
+	if (!IS_ERR(mem)) {
+		DRM_INFO("Intel graphics fake LMEM: %pR\n", &mem->region);
+		DRM_INFO("Intel graphics fake LMEM IO start: %llx\n",
+			 (u64)mem->io_start);
+	}
+
+	return mem;
+}
+
diff --git a/drivers/gpu/drm/i915/intel_region_lmem.h b/drivers/gpu/drm/i915/intel_region_lmem.h
index a76b77b69e71..33aadbaba4e0 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.h
+++ b/drivers/gpu/drm/i915/intel_region_lmem.h
@@ -40,4 +40,7 @@ i915_gem_object_create_lmem(struct drm_i915_private *i915,
 			    resource_size_t size,
 			    unsigned int flags);
 
+struct intel_memory_region *
+i915_gem_setup_fake_lmem(struct drm_i915_private *i915);
+
 #endif /* !__INTEL_REGION_LMEM_H */
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index c44703f471b3..59865a2d4305 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -39,6 +39,9 @@ extern bool i915_gpu_turbo_disable(void);
 /* Exported from arch/x86/kernel/early-quirks.c */
 extern struct resource intel_graphics_stolen_res;
 
+/* Exported from arch/x86/kernel/early-printk.c */
+extern struct resource intel_graphics_fake_lmem_res;
+
 /*
  * The Bridge device's PCI config space has information about the
  * fb aperture size and the amount of pre-reserved memory.
-- 
2.20.1

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