[PATCH v2 36/37] 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>
---
 drivers/gpu/drm/i915/i915_drv.c            | 15 +++++
 drivers/gpu/drm/i915/i915_drv.h            |  2 +
 drivers/gpu/drm/i915/i915_gem_gtt.c        |  3 +
 drivers/gpu/drm/i915/i915_params.c         |  3 +
 drivers/gpu/drm/i915/i915_params.h         |  3 +-
 drivers/gpu/drm/i915/intel_memory_region.h |  4 ++
 drivers/gpu/drm/i915/intel_region_lmem.c   | 76 ++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_region_lmem.h   |  3 +
 8 files changed, 108 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 3d6fe993f26e..891937de6a2b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1869,6 +1869,9 @@ static void i915_driver_destroy(struct drm_i915_private *i915)
 	pci_set_drvdata(pdev, NULL);
 }
 
+struct resource intel_graphics_fake_lmem_res __ro_after_init = DEFINE_RES_MEM(0, 0);
+EXPORT_SYMBOL(intel_graphics_fake_lmem_res);
+
 /**
  * i915_driver_load - setup chip and create an initial config
  * @pdev: PCI device
@@ -1895,6 +1898,18 @@ 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 && i915_modparams.fake_lmem_start > 0) {
+		intel_graphics_fake_lmem_res.start = i915_modparams.fake_lmem_start;
+		intel_graphics_fake_lmem_res.end = SZ_2G; /* Placeholder; depends on aperture size */
+
+		mkwrite_device_info(dev_priv)->memory_regions =
+			REGION_SMEM | REGION_LMEM;
+		GEM_BUG_ON(!HAS_LMEM(dev_priv));
+
+		pr_info("Intel graphics fake LMEM starts at %pa\n", &intel_graphics_fake_lmem_res.start);
+	}
+
 	ret = pci_enable_device(pdev);
 	if (ret)
 		goto out_fini;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 715e630a872d..9a2c79fa8088 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2815,4 +2815,6 @@ static inline void add_taint_for_CI(unsigned int taint)
 	add_taint(taint, LOCKDEP_STILL_OK);
 }
 
+extern struct resource intel_graphics_fake_lmem_res;
+
 #endif
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 3a8965048a06..df4928c8b10a 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2938,6 +2938,9 @@ int i915_gem_init_memory_regions(struct drm_i915_private *i915)
 		case INTEL_STOLEN:
 			mem = i915_gem_stolen_setup(i915);
 			break;
+		case INTEL_LMEM:
+			mem = i915_gem_setup_fake_lmem(i915);
+			break;
 		}
 
 		if (IS_ERR(mem)) {
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 296452f9efe4..59a6ad6261b9 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -164,6 +164,9 @@ i915_param_named_unsafe(dmc_firmware_path, charp, 0400,
 i915_param_named_unsafe(enable_dp_mst, bool, 0600,
 	"Enable multi-stream transport (MST) for new DisplayPort sinks. (default: true)");
 
+i915_param_named_unsafe(fake_lmem_start, ulong, 0600,
+	"Fake LMEM start offset (default: 0)");
+
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 i915_param_named_unsafe(inject_load_failure, uint, 0400,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index d29ade3b7de6..b9698722c957 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -77,7 +77,8 @@ struct drm_printer;
 	param(bool, verbose_state_checks, true) \
 	param(bool, nuclear_pageflip, false) \
 	param(bool, enable_dp_mst, true) \
-	param(bool, enable_gvt, false)
+	param(bool, enable_gvt, false) \
+	param(unsigned long, fake_lmem_start, 0)
 
 #define MEMBER(T, member, ...) T member;
 struct i915_params {
diff --git a/drivers/gpu/drm/i915/intel_memory_region.h b/drivers/gpu/drm/i915/intel_memory_region.h
index bee0c022d295..4960096ec30f 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.h
+++ b/drivers/gpu/drm/i915/intel_memory_region.h
@@ -9,6 +9,7 @@
 #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 faking for lmem */
+	struct drm_mm_node fake_mappable;
+
 	struct i915_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 7003e7bff90c..2028261f4e80 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/intel_region_lmem.c
@@ -241,9 +241,41 @@ lmem_create_object(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);
 }
@@ -253,6 +285,14 @@ 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);
+		if (ret) {
+			GEM_BUG_ON(1);
+			return ret;
+		}
+	}
+
 	if (!io_mapping_init_wc(&mem->iomap,
 				mem->io_start,
 				resource_size(&mem->region)))
@@ -278,6 +318,7 @@ 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);
 }
@@ -291,6 +332,7 @@ 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);
 }
@@ -307,6 +349,7 @@ resource_size_t i915_gem_object_lmem_io_offset(struct drm_i915_gem_object *obj,
 	 * here, and elsewhere like in the gtt paths.
 	 */
 	daddr = i915_gem_object_get_dma_address(obj, n);
+	daddr -= intel_graphics_fake_lmem_res.start;
 
 	return mem->io_start + daddr;
 }
@@ -326,3 +369,36 @@ 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 68232615a874..41bc411068de 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.h
+++ b/drivers/gpu/drm/i915/intel_region_lmem.h
@@ -24,4 +24,7 @@ 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 */
-- 
2.20.1

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