sna: Experiment with a new ioctl to create buffers from stolen memory

If there is stolen memory reserved by the BIOS, we want to utilize it in
preference to regular system memory. However, given the caveat that it
is not suitable for CPU access, rules out most use cases - but it is a
good match for framebuffers.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 111 insertions, 12 deletions

diff --git a/src/sna/kgem.c b/src/sna/kgem.c
index cb6276d6..7091ca4e 100644
--- a/src/sna/kgem.c
+++ b/src/sna/kgem.c
@@ -61,6 +61,7 @@ search_snoop_cache(struct kgem *kgem, unsigned int num_pages, unsigned flags);
 #define DBG_NO_CACHE 0
 #define DBG_NO_CACHE_LEVEL 0
 #define DBG_NO_CPU 0
+#define DBG_NO_CREATE2 0
 #define DBG_NO_USERPTR 0
 #define DBG_NO_UNSYNCHRONIZED_USERPTR 0
 #define DBG_NO_LLC 0
@@ -126,7 +127,21 @@ search_snoop_cache(struct kgem *kgem, unsigned int num_pages, unsigned flags);
 #define LOCAL_I915_EXEC_NO_RELOC		(1<<11)
 #define LOCAL_I915_EXEC_HANDLE_LUT		(1<<12)
 
-#define LOCAL_I915_GEM_USERPTR       0x32
+#define LOCAL_I915_GEM_CREATE2       0x32
+#define LOCAL_IOCTL_I915_GEM_CREATE2 DRM_IOWR (DRM_COMMAND_BASE + LOCAL_I915_GEM_CREATE2, struct local_i915_gem_create2)
+struct local_i915_gem_create2 {
+	uint64_t size;
+	uint32_t domain;
+#define LOCAL_I915_CREATE_DOMAIN_SYSTEM 0
+#define LOCAL_I915_CREATE_DOMAIN_STOLEN 1
+	uint32_t caching;
+	uint32_t tiling_mode;
+	uint32_t stride;
+	uint32_t flags;
+	uint32_t handle;
+};
+
+#define LOCAL_I915_GEM_USERPTR       0x33
 #define LOCAL_IOCTL_I915_GEM_USERPTR DRM_IOWR (DRM_COMMAND_BASE + LOCAL_I915_GEM_USERPTR, struct local_i915_gem_userptr)
 struct local_i915_gem_userptr {
 	uint64_t user_ptr;
@@ -890,6 +905,31 @@ static bool test_has_userptr(struct kgem *kgem)
 #endif
 }
 
+static bool test_has_create2(struct kgem *kgem)
+{
+#if defined(USE_CREATE2)
+	struct local_i915_gem_create2 args;
+
+	if (DBG_NO_CREATE2)
+		return false;
+
+	VG_CLEAR(args);
+	args.size = PAGE_SIZE;
+	args.domain = LOCAL_I915_CREATE_DOMAIN_SYSTEM;
+	args.caching = UNCACHED;
+	args.tiling_mode = I915_TILING_NONE;
+	args.stride = 0;
+	args.flags = 0;
+	args.handle = 0;
+	if (drmIoctl(kgem->fd, LOCAL_IOCTL_I915_GEM_CREATE2, &args) == 0)
+		gem_close(kgem->fd, args.handle);
+
+	return args.handle != 0;
+#else
+	return false;
+#endif
+}
+
 static bool test_has_secure_batches(struct kgem *kgem)
 {
 	if (DBG_NO_SECURE_BATCHES)
@@ -1071,6 +1111,10 @@ void kgem_init(struct kgem *kgem, int fd, struct pci_device *dev, unsigned gen)
 	DBG(("%s: has userptr? %d\n", __FUNCTION__,
 	     kgem->has_userptr));
 
+	kgem->has_create2 = test_has_create2(kgem);
+	DBG(("%s: has create2? %d\n", __FUNCTION__,
+	     kgem->has_create2));
+
 	kgem->has_no_reloc = test_has_no_reloc(kgem);
 	DBG(("%s: has no-reloc? %d\n", __FUNCTION__,
 	     kgem->has_no_reloc));
@@ -1846,7 +1890,7 @@ static void __kgem_bo_destroy(struct kgem *kgem, struct kgem_bo *bo)
 
 	assert(list_is_empty(&bo->list));
 	assert(bo->refcnt == 0);
-	assert(!bo->purged);
+	assert(!bo->purged || !bo->reusable);
 	assert(bo->proxy == NULL);
 	assert_tiling(kgem, bo);
 
@@ -2196,7 +2240,6 @@ static void kgem_commit(struct kgem *kgem)
 		     bo->gpu_dirty, bo->needs_flush, bo->snoop,
 		     (unsigned)bo->exec->offset));
 
-		assert(!bo->purged);
 		assert(bo->exec);
 		assert(bo->proxy == NULL || bo->exec == &_kgem_dummy_exec);
 		assert(RQ(bo->rq) == rq || (RQ(bo->proxy->rq) == rq));
@@ -2912,8 +2955,11 @@ void kgem_clean_scanout_cache(struct kgem *kgem)
 			break;
 
 		list_del(&bo->list);
-		kgem_bo_clear_scanout(kgem, bo);
-		__kgem_bo_destroy(kgem, bo);
+		if (!bo->purged) {
+			kgem_bo_clear_scanout(kgem, bo);
+			__kgem_bo_destroy(kgem, bo);
+		} else
+			kgem_bo_free(kgem, bo);
 	}
 }
 
@@ -3683,6 +3729,45 @@ inline int kgem_bo_fenced_size(struct kgem *kgem, struct kgem_bo *bo)
 	return size;
 }
 
+static struct kgem_bo *
+__kgem_bo_create_from_stolen(struct kgem *kgem, int size, int tiling, int pitch)
+
+{
+	struct local_i915_gem_create2 args;
+	struct kgem_bo *bo;
+
+	if (!kgem->has_create2)
+		return NULL;
+
+	VG_CLEAR(args);
+	args.size = size * PAGE_SIZE;
+	args.domain = LOCAL_I915_CREATE_DOMAIN_STOLEN;
+	args.caching = UNCACHED;
+	args.tiling_mode = tiling;
+	args.stride = pitch;
+	args.flags = 0;
+
+	if (drmIoctl(kgem->fd, LOCAL_IOCTL_I915_GEM_CREATE2, &args))
+		return NULL;
+
+	bo = __kgem_bo_alloc(args.handle, size);
+	if (bo == NULL) {
+		gem_close(kgem->fd, args.handle);
+		return NULL;
+	}
+
+	bo->unique_id = kgem_get_unique_id(kgem);
+	bo->tiling = tiling;
+	bo->pitch = pitch;
+	bo->purged = true; /* for asserts against CPU access */
+	bo->reusable = false; /* so that unclaimed scanouts are freed */
+
+	assert_tiling(kgem, bo);
+	debug_alloc__bo(kgem, bo);
+
+	return bo;
+}
+
 struct kgem_bo *kgem_create_2d(struct kgem *kgem,
 			       int width,
 			       int height,
@@ -3720,7 +3805,6 @@ struct kgem_bo *kgem_create_2d(struct kgem *kgem,
 		list_for_each_entry_reverse(bo, &kgem->scanout, list) {
 			assert(bo->scanout);
 			assert(bo->delta);
-			assert(!bo->purged);
 			assert(!bo->flush);
 			assert_tiling(kgem, bo);
 
@@ -3750,6 +3834,10 @@ struct kgem_bo *kgem_create_2d(struct kgem *kgem,
 			bo->refcnt = 1;
 			return bo;
 		}
+
+		bo = __kgem_bo_create_from_stolen(kgem, size, tiling, pitch);
+		if (bo)
+			return bo;
 	}
 
 	if (bucket >= NUM_CACHE_BUCKETS) {
@@ -4420,8 +4508,11 @@ bool kgem_check_bo_fenced(struct kgem *kgem, struct kgem_bo *bo)
 {
 	uint32_t size;
 
+	assert(bo->refcnt);
 	while (bo->proxy)
 		bo = bo->proxy;
+	assert(bo->refcnt);
+
 	if (bo->exec) {
 		if (kgem->gen < 040 &&
 		    bo->tiling != I915_TILING_NONE &&
@@ -4488,8 +4579,10 @@ bool kgem_check_many_bo_fenced(struct kgem *kgem, ...)
 
 	va_start(ap, kgem);
 	while ((bo = va_arg(ap, struct kgem_bo *))) {
+		assert(bo->refcnt);
 		while (bo->proxy)
 			bo = bo->proxy;
+		assert(bo->refcnt);
 		if (bo->exec) {
 			if (kgem->gen >= 040 || bo->tiling == I915_TILING_NONE)
 				continue;
@@ -4565,8 +4658,6 @@ uint32_t kgem_add_reloc(struct kgem *kgem,
 	kgem->reloc[index].offset = pos * sizeof(kgem->batch[0]);
 	if (bo) {
 		assert(bo->refcnt);
-		assert(!bo->purged);
-
 		while (bo->proxy) {
 			DBG(("%s: adding proxy [delta=%d] for handle=%d\n",
 			     __FUNCTION__, bo->delta, bo->handle));
@@ -4586,8 +4677,8 @@ uint32_t kgem_add_reloc(struct kgem *kgem,
 
 			bo = bo->proxy;
 			assert(bo->refcnt);
-			assert(!bo->purged);
 		}
+		assert(bo->refcnt);
 
 		if (bo->exec == NULL)
 			kgem_add_bo(kgem, bo);
@@ -4689,7 +4780,6 @@ void *kgem_bo_map__async(struct kgem *kgem, struct kgem_bo *bo)
 	DBG(("%s: handle=%d, offset=%d, tiling=%d, map=%p, domain=%d\n", __FUNCTION__,
 	     bo->handle, bo->presumed_offset, bo->tiling, bo->map, bo->domain));
 
-	assert(!bo->purged);
 	assert(bo->proxy == NULL);
 	assert(list_is_empty(&bo->list));
 	assert(!IS_USER_MAP(bo->map));
@@ -4733,7 +4823,6 @@ void *kgem_bo_map(struct kgem *kgem, struct kgem_bo *bo)
 	DBG(("%s: handle=%d, offset=%d, tiling=%d, map=%p, domain=%d\n", __FUNCTION__,
 	     bo->handle, bo->presumed_offset, bo->tiling, bo->map, bo->domain));
 
-	assert(!bo->purged);
 	assert(bo->proxy == NULL);
 	assert(list_is_empty(&bo->list));
 	assert(!IS_USER_MAP(bo->map));
@@ -4802,7 +4891,6 @@ void *kgem_bo_map__gtt(struct kgem *kgem, struct kgem_bo *bo)
 	DBG(("%s: handle=%d, offset=%d, tiling=%d, map=%p, domain=%d\n", __FUNCTION__,
 	     bo->handle, bo->presumed_offset, bo->tiling, bo->map, bo->domain));
 
-	assert(!bo->purged);
 	assert(bo->exec == NULL);
 	assert(list_is_empty(&bo->list));
 	assert(!IS_USER_MAP(bo->map));
@@ -5041,8 +5129,12 @@ void kgem_bo_sync__cpu(struct kgem *kgem, struct kgem_bo *bo)
 	kgem_bo_submit(kgem, bo);
 
 	/* SHM pixmaps use proxies for subpage offsets */
+	assert(!bo->purged);
+	assert(bo->refcnt);
 	while (bo->proxy)
 		bo = bo->proxy;
+	assert(bo->refcnt);
+	assert(!bo->purged);
 
 	if (bo->domain != DOMAIN_CPU || FORCE_MMAP_SYNC & (1 << DOMAIN_CPU)) {
 		struct drm_i915_gem_set_domain set_domain;
@@ -5072,8 +5164,12 @@ void kgem_bo_sync__cpu_full(struct kgem *kgem, struct kgem_bo *bo, bool write)
 		kgem_bo_submit(kgem, bo);
 
 	/* SHM pixmaps use proxies for subpage offsets */
+	assert(!bo->purged);
+	assert(bo->refcnt);
 	while (bo->proxy)
 		bo = bo->proxy;
+	assert(bo->refcnt);
+	assert(!bo->purged);
 
 	if (bo->domain != DOMAIN_CPU || FORCE_MMAP_SYNC & (1 << DOMAIN_CPU)) {
 		struct drm_i915_gem_set_domain set_domain;
@@ -5099,7 +5195,9 @@ void kgem_bo_sync__cpu_full(struct kgem *kgem, struct kgem_bo *bo, bool write)
 void kgem_bo_sync__gtt(struct kgem *kgem, struct kgem_bo *bo)
 {
 	DBG(("%s: handle=%d\n", __FUNCTION__, bo->handle));
+	assert(bo->refcnt);
 	assert(bo->proxy == NULL);
+
 	kgem_bo_submit(kgem, bo);
 
 	if (bo->domain != DOMAIN_GTT || FORCE_MMAP_SYNC & (1 << DOMAIN_GTT)) {
diff --git a/src/sna/kgem.h b/src/sna/kgem.h
index 044dbba0..8e8e883d 100644
--- a/src/sna/kgem.h
+++ b/src/sna/kgem.h
@@ -169,6 +169,7 @@ struct kgem {
 	uint32_t scanout_busy:1;
 	uint32_t busy:1;
 
+	uint32_t has_create2 :1;
 	uint32_t has_userptr :1;
 	uint32_t has_blt :1;
 	uint32_t has_relaxed_fencing :1;