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 <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191030173320.8850-1-matthew.auld@intel.com

1 files changed, 92 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_region_lmem.c b/drivers/gpu/drm/i915/intel_region_lmem.c
index 9a351af45ce6..583118095635 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.c
+++ b/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;
+}