drm/i915/lmem: add the fake lmem region

Intended for upstream testing so that we can still exercise the LMEM
plumbing and !i915_ggtt_has_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 the i915 modparam 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. For now we only
enable for the selftests. Depends on CONFIG_DRM_I915_UNSTABLE being
enabled.

eg. memmap=2G$16G i915.fake_lmem_start=0x400000000

v2: make fake_lmem_start an i915 modparam

Signed-off-by: Matthew Auld <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Abdiel Janulgue <[email protected]>
Cc: Arkadiusz Hiler <[email protected]>
Cc: Chris Wilson <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: matt-auld

drivers/gpu/drm/i915/Kconfig.unstable

@@ -19,3 +19,11 @@ config DRM_I915_UNSTABLE
 	  Recommended for driver developers _only_.
 
 	  If in the slightest bit of doubt, say "N".
+
+config DRM_I915_UNSTABLE_FAKE_LMEM
+	bool "Enable the experimental fake lmem"
+	depends on DRM_I915_UNSTABLE
+	default n
+	help
+	  Convert some system memory into a fake local memory region for
+	  testing.

drivers/gpu/drm/i915/gem/i915_gem_lmem.c

@@ -24,6 +24,7 @@ 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 -= obj->mm.region->region.start;
 
 	return io_mapping_map_wc(&obj->mm.region->iomap, offset, PAGE_SIZE);
 }
@@ -35,6 +36,7 @@ i915_gem_object_lmem_io_map_page_atomic(struct drm_i915_gem_object *obj,
 	resource_size_t offset;
 
 	offset = i915_gem_object_get_dma_address(obj, n);
+	offset -= obj->mm.region->region.start;
 
 	return io_mapping_map_atomic_wc(&obj->mm.region->iomap, offset);
 }
@@ -49,6 +51,7 @@ i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,
 	GEM_BUG_ON(!i915_gem_object_is_contiguous(obj));
 
 	offset = i915_gem_object_get_dma_address(obj, n);
+	offset -= obj->mm.region->region.start;
 
 	return io_mapping_map_wc(&obj->mm.region->iomap, offset, size);
 }

drivers/gpu/drm/i915/i915_drv.c

@@ -1483,6 +1483,21 @@ int i915_driver_probe(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 support fake LMEM -- for now we only unleash this for
+	 * the live selftests(test-and-exit).
+	 */
+	if (IS_ENABLED(CONFIG_DRM_I915_UNSTABLE_FAKE_LMEM)) {
+		if (INTEL_GEN(dev_priv) >= 9 && i915_selftest.live < 0 &&
+		    i915_modparams.fake_lmem_start) {
+			mkwrite_device_info(dev_priv)->memory_regions =
+				REGION_SMEM | REGION_LMEM | REGION_STOLEN;
+			mkwrite_device_info(dev_priv)->is_dgfx = true;
+			GEM_BUG_ON(!HAS_LMEM(dev_priv));
+			GEM_BUG_ON(!IS_DGFX(dev_priv));
+		}
+	}
+
 	ret = pci_enable_device(pdev);
 	if (ret)
 		goto out_fini;

drivers/gpu/drm/i915/i915_params.c

@@ -179,6 +179,11 @@ i915_param_named(enable_gvt, bool, 0400,
 	"Enable support for Intel GVT-g graphics virtualization host support(default:false)");
 #endif
 
+#if IS_ENABLED(CONFIG_DRM_I915_UNSTABLE_FAKE_LMEM)
+i915_param_named_unsafe(fake_lmem_start, ulong, 0600,
+	"Fake LMEM start offset (default: 0)");
+#endif
+
 static __always_inline void _print_param(struct drm_printer *p,
 					 const char *name,
 					 const char *type,
@@ -190,6 +195,8 @@ static __always_inline void _print_param(struct drm_printer *p,
 		drm_printf(p, "i915.%s=%d\n", name, *(const int *)x);
 	else if (!__builtin_strcmp(type, "unsigned int"))
 		drm_printf(p, "i915.%s=%u\n", name, *(const unsigned int *)x);
+	else if (!__builtin_strcmp(type, "unsigned long"))
+		drm_printf(p, "i915.%s=%lu\n", name, *(const unsigned long *)x);
 	else if (!__builtin_strcmp(type, "char *"))
 		drm_printf(p, "i915.%s=%s\n", name, *(const char **)x);
 	else

drivers/gpu/drm/i915/i915_params.h

@@ -66,6 +66,7 @@ struct drm_printer;
 	param(int, fastboot, -1) \
 	param(int, enable_dpcd_backlight, 0) \
 	param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE) \
+	param(unsigned long, fake_lmem_start, 0) \
 	/* leave bools at the end to not create holes */ \
 	param(bool, alpha_support, IS_ENABLED(CONFIG_DRM_I915_ALPHA_SUPPORT)) \
 	param(bool, enable_hangcheck, true) \

drivers/gpu/drm/i915/intel_memory_region.c

@@ -228,6 +228,9 @@ int intel_memory_regions_hw_probe(struct drm_i915_private *i915)
 		case INTEL_MEMORY_STOLEN:
 			mem = i915_gem_stolen_setup(i915);
 			break;
+		case INTEL_MEMORY_LOCAL:
+			mem = intel_setup_fake_lmem(i915);
+			break;
 		}
 
 		if (IS_ERR(mem)) {

drivers/gpu/drm/i915/intel_memory_region.h

@@ -10,6 +10,7 @@
 #include <linux/ioport.h>
 #include <linux/mutex.h>
 #include <linux/io-mapping.h>
+#include <drm/drm_mm.h>
 
 #include "i915_buddy.h"
 
@@ -71,6 +72,9 @@ struct intel_memory_region {
 	struct io_mapping iomap;
 	struct resource region;
 
+	/* For fake LMEM */
+	struct drm_mm_node fake_mappable;
+
 	struct i915_buddy_mm mm;
 	struct mutex mm_lock;
 
@@ -83,6 +87,8 @@ struct intel_memory_region {
 	unsigned int instance;
 	unsigned int id;
 
+	dma_addr_t remap_addr;
+
 	struct {
 		struct mutex lock; /* Protects access to objects */
 		struct list_head list;

drivers/gpu/drm/i915/intel_region_lmem.c

@@ -9,9 +9,62 @@
 #include "gem/i915_gem_region.h"
 #include "intel_region_lmem.h"
 
+static int 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;
+
+	/* We want to 1:1 map the mappable aperture to our reserved region */
+
+	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;
+
+	mem->remap_addr = dma_map_resource(&i915->drm.pdev->dev,
+					   mem->region.start,
+					   mem->fake_mappable.size,
+					   PCI_DMA_BIDIRECTIONAL,
+					   DMA_ATTR_FORCE_CONTIGUOUS);
+	if (dma_mapping_error(&i915->drm.pdev->dev, mem->remap_addr)) {
+		drm_mm_remove_node(&mem->fake_mappable);
+		return -EINVAL;
+	}
+
+	for (n = 0; n < mem->fake_mappable.size >> PAGE_SHIFT; ++n) {
+		ggtt->vm.insert_page(&ggtt->vm,
+				     mem->remap_addr + (n << PAGE_SHIFT),
+				     n << PAGE_SHIFT,
+				     I915_CACHE_NONE, 0);
+	}
+
+	mem->region = (struct resource)DEFINE_RES_MEM(mem->remap_addr,
+						      mem->fake_mappable.size);
+
+	return 0;
+}
+
+static void release_fake_lmem_bar(struct intel_memory_region *mem)
+{
+	if (drm_mm_node_allocated(&mem->fake_mappable))
+		drm_mm_remove_node(&mem->fake_mappable);
+
+	dma_unmap_resource(&mem->i915->drm.pdev->dev,
+			   mem->remap_addr,
+			   mem->fake_mappable.size,
+			   PCI_DMA_BIDIRECTIONAL,
+			   DMA_ATTR_FORCE_CONTIGUOUS);
+}
+
 static void
 region_lmem_release(struct intel_memory_region *mem)
 {
+	release_fake_lmem_bar(mem);
 	io_mapping_fini(&mem->iomap);
 	intel_memory_region_release_buddy(mem);
 }
@@ -21,6 +74,11 @@ region_lmem_init(struct intel_memory_region *mem)
 {
 	int ret;
 
+	if (i915_modparams.fake_lmem_start) {
+		ret = init_fake_lmem_bar(mem);
+		GEM_BUG_ON(ret);
+	}
+
 	if (!io_mapping_init_wc(&mem->iomap,
 				mem->io_start,
 				resource_size(&mem->region)))
@@ -38,3 +96,37 @@ const struct intel_memory_region_ops intel_region_lmem_ops = {
 	.release = region_lmem_release,
 	.create_object = __i915_gem_lmem_object_create,
 };
+
+struct intel_memory_region *
+intel_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(i915_ggtt_has_aperture(&i915->ggtt));
+	GEM_BUG_ON(!i915_modparams.fake_lmem_start);
+
+	/* Your mappable aperture belongs to me now! */
+	mappable_end = pci_resource_len(pdev, 2);
+	io_start = pci_resource_start(pdev, 2),
+	start = i915_modparams.fake_lmem_start;
+
+	mem = intel_memory_region_create(i915,
+					 start,
+					 mappable_end,
+					 PAGE_SIZE,
+					 io_start,
+					 &intel_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);
+		DRM_INFO("Intel graphics fake LMEM size: %llx\n",
+			 (u64)resource_size(&mem->region));
+	}
+
+	return mem;
+}

drivers/gpu/drm/i915/intel_region_lmem.h

@@ -6,6 +6,11 @@
 #ifndef __INTEL_REGION_LMEM_H
 #define __INTEL_REGION_LMEM_H
 
+struct drm_i915_private;
+
 extern const struct intel_memory_region_ops intel_region_lmem_ops;
 
+struct intel_memory_region *
+intel_setup_fake_lmem(struct drm_i915_private *i915);
+
 #endif /* !__INTEL_REGION_LMEM_H */