drm/i915: Use struct vma_resource instead of struct vma_snapshot

There is always a struct vma_resource guaranteed to be alive when we
access a corresponding struct vma_snapshot.

So ditch the latter and instead of allocating vma_snapshots, reference
the already existning vma_resource.

This requires a couple of extra members in struct vma_resource but that's
a small price to pay for the simplification.

v2:
- Fix a missing include and declaration (kernel test robot <lkp@intel.com>)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220110172219.107131-7-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/i915/Makefile

@@ -175,7 +175,6 @@ i915-y += \
 	  i915_ttm_buddy_manager.o \
 	  i915_vma.o \
 	  i915_vma_resource.o \
-	  i915_vma_snapshot.o \
 	  intel_wopcm.o
 
 # general-purpose microcontroller (GuC) support

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -29,7 +29,6 @@
 #include "i915_gem_ioctls.h"
 #include "i915_trace.h"
 #include "i915_user_extensions.h"
-#include "i915_vma_snapshot.h"
 
 struct eb_vma {
 	struct i915_vma *vma;
@@ -1941,7 +1940,6 @@ static void eb_capture_stage(struct i915_execbuffer *eb)
 {
 	const unsigned int count = eb->buffer_count;
 	unsigned int i = count, j;
-	struct i915_vma_snapshot *vsnap;
 
 	while (i--) {
 		struct eb_vma *ev = &eb->vma[i];
@@ -1951,11 +1949,6 @@ static void eb_capture_stage(struct i915_execbuffer *eb)
 		if (!(flags & EXEC_OBJECT_CAPTURE))
 			continue;
 
-		vsnap = i915_vma_snapshot_alloc(GFP_KERNEL);
-		if (!vsnap)
-			continue;
-
-		i915_vma_snapshot_init(vsnap, vma, "user");
 		for_each_batch_create_order(eb, j) {
 			struct i915_capture_list *capture;
 
@@ -1964,10 +1957,9 @@ static void eb_capture_stage(struct i915_execbuffer *eb)
 				continue;
 
 			capture->next = eb->capture_lists[j];
-			capture->vma_snapshot = i915_vma_snapshot_get(vsnap);
+			capture->vma_res = i915_vma_resource_get(vma->resource);
 			eb->capture_lists[j] = capture;
 		}
-		i915_vma_snapshot_put(vsnap);
 	}
 }
 
@@ -3270,9 +3262,8 @@ eb_requests_create(struct i915_execbuffer *eb, struct dma_fence *in_fence,
 		 * _onstack interface.
 		 */
 		if (eb->batches[i]->vma)
-			i915_vma_snapshot_init_onstack(&eb->requests[i]->batch_snapshot,
-						       eb->batches[i]->vma,
-						       "batch");
+			eb->requests[i]->batch_res =
+				i915_vma_resource_get(eb->batches[i]->vma->resource);
 		if (eb->batch_pool) {
 			GEM_BUG_ON(intel_context_is_parallel(eb->context));
 			intel_gt_buffer_pool_mark_active(eb->batch_pool,

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -1708,18 +1708,15 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
 
 static void print_request_ring(struct drm_printer *m, struct i915_request *rq)
 {
-	struct i915_vma_snapshot *vsnap = &rq->batch_snapshot;
+	struct i915_vma_resource *vma_res = rq->batch_res;
 	void *ring;
 	int size;
 
-	if (!i915_vma_snapshot_present(vsnap))
-		vsnap = NULL;
-
 	drm_printf(m,
 		   "[head %04x, postfix %04x, tail %04x, batch 0x%08x_%08x]:\n",
 		   rq->head, rq->postfix, rq->tail,
-		   vsnap ? upper_32_bits(vsnap->vma_resource->start) : ~0u,
-		   vsnap ? lower_32_bits(vsnap->vma_resource->start) : ~0u);
+		   vma_res ? upper_32_bits(vma_res->start) : ~0u,
+		   vma_res ? lower_32_bits(vma_res->start) : ~0u);
 
 	size = rq->tail - rq->head;
 	if (rq->tail < rq->head)

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -48,7 +48,6 @@
 #include "i915_gpu_error.h"
 #include "i915_memcpy.h"
 #include "i915_scatterlist.h"
-#include "i915_vma_snapshot.h"
 
 #define ALLOW_FAIL (__GFP_KSWAPD_RECLAIM | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)
 #define ATOMIC_MAYFAIL (GFP_ATOMIC | __GFP_NOWARN)
@@ -1013,8 +1012,10 @@ void __i915_gpu_coredump_free(struct kref *error_ref)
 
 static struct i915_vma_coredump *
 i915_vma_coredump_create(const struct intel_gt *gt,
-			 const struct i915_vma_snapshot *vsnap,
-			 struct i915_vma_compress *compress)
+			 const struct i915_vma_resource *vma_res,
+			 struct i915_vma_compress *compress,
+			 const char *name)
+
 {
 	struct i915_ggtt *ggtt = gt->ggtt;
 	const u64 slot = ggtt->error_capture.start;
@@ -1024,7 +1025,7 @@ i915_vma_coredump_create(const struct intel_gt *gt,
 
 	might_sleep();
 
-	if (!vsnap || !vsnap->pages || !compress)
+	if (!vma_res || !vma_res->bi.pages || !compress)
 		return NULL;
 
 	dst = kmalloc(sizeof(*dst), ALLOW_FAIL);
@@ -1037,20 +1038,20 @@ i915_vma_coredump_create(const struct intel_gt *gt,
 	}
 
 	INIT_LIST_HEAD(&dst->page_list);
-	strcpy(dst->name, vsnap->name);
+	strcpy(dst->name, name);
 	dst->next = NULL;
 
-	dst->gtt_offset = vsnap->vma_resource->start;
-	dst->gtt_size = vsnap->vma_resource->node_size;
-	dst->gtt_page_sizes = vsnap->vma_resource->page_sizes_gtt;
+	dst->gtt_offset = vma_res->start;
+	dst->gtt_size = vma_res->node_size;
+	dst->gtt_page_sizes = vma_res->page_sizes_gtt;
 	dst->unused = 0;
 
 	ret = -EINVAL;
 	if (drm_mm_node_allocated(&ggtt->error_capture)) {
 		void __iomem *s;
 		dma_addr_t dma;
 
-		for_each_sgt_daddr(dma, iter, vsnap->pages) {
+		for_each_sgt_daddr(dma, iter, vma_res->bi.pages) {
 			mutex_lock(&ggtt->error_mutex);
 			ggtt->vm.insert_page(&ggtt->vm, dma, slot,
 					     I915_CACHE_NONE, 0);
@@ -1068,11 +1069,11 @@ i915_vma_coredump_create(const struct intel_gt *gt,
 			if (ret)
 				break;
 		}
-	} else if (vsnap->mr && vsnap->mr->type != INTEL_MEMORY_SYSTEM) {
-		struct intel_memory_region *mem = vsnap->mr;
+	} else if (vma_res->bi.lmem) {
+		struct intel_memory_region *mem = vma_res->mr;
 		dma_addr_t dma;
 
-		for_each_sgt_daddr(dma, iter, vsnap->pages) {
+		for_each_sgt_daddr(dma, iter, vma_res->bi.pages) {
 			void __iomem *s;
 
 			s = io_mapping_map_wc(&mem->iomap,
@@ -1088,7 +1089,7 @@ i915_vma_coredump_create(const struct intel_gt *gt,
 	} else {
 		struct page *page;
 
-		for_each_sgt_page(page, iter, vsnap->pages) {
+		for_each_sgt_page(page, iter, vma_res->bi.pages) {
 			void *s;
 
 			drm_clflush_pages(&page, 1);
@@ -1324,33 +1325,32 @@ static bool record_context(struct i915_gem_context_coredump *e,
 
 struct intel_engine_capture_vma {
 	struct intel_engine_capture_vma *next;
-	struct i915_vma_snapshot *vsnap;
+	struct i915_vma_resource *vma_res;
 	char name[16];
 	bool lockdep_cookie;
 };
 
 static struct intel_engine_capture_vma *
 capture_vma_snapshot(struct intel_engine_capture_vma *next,
-		     struct i915_vma_snapshot *vsnap,
-		     gfp_t gfp)
+		     struct i915_vma_resource *vma_res,
+		     gfp_t gfp, const char *name)
 {
 	struct intel_engine_capture_vma *c;
 
-	if (!i915_vma_snapshot_present(vsnap))
+	if (!vma_res)
 		return next;
 
 	c = kmalloc(sizeof(*c), gfp);
 	if (!c)
 		return next;
 
-	if (!i915_vma_snapshot_resource_pin(vsnap, &c->lockdep_cookie)) {
+	if (!i915_vma_resource_hold(vma_res, &c->lockdep_cookie)) {
 		kfree(c);
 		return next;
 	}
 
-	strcpy(c->name, vsnap->name);
-	c->vsnap = vsnap;
-	i915_vma_snapshot_get(vsnap);
+	strcpy(c->name, name);
+	c->vma_res = i915_vma_resource_get(vma_res);
 
 	c->next = next;
 	return c;
@@ -1362,8 +1362,6 @@ capture_vma(struct intel_engine_capture_vma *next,
 	    const char *name,
 	    gfp_t gfp)
 {
-	struct i915_vma_snapshot *vsnap;
-
 	if (!vma)
 		return next;
 
@@ -1372,19 +1370,10 @@ capture_vma(struct intel_engine_capture_vma *next,
 	 * to a struct i915_vma_snapshot at command submission time.
 	 * Not here.
 	 */
-	GEM_WARN_ON(!i915_vma_is_pinned(vma));
-	if (!i915_vma_is_pinned(vma))
-		return next;
-
-	vsnap = i915_vma_snapshot_alloc(gfp);
-	if (!vsnap)
+	if (GEM_WARN_ON(!i915_vma_is_pinned(vma)))
 		return next;
 
-	i915_vma_snapshot_init(vsnap, vma, name);
-	next = capture_vma_snapshot(next, vsnap, gfp);
-
-	/* FIXME: Replace on async unbind. */
-	i915_vma_snapshot_put(vsnap);
+	next = capture_vma_snapshot(next, vma->resource, gfp, name);
 
 	return next;
 }
@@ -1397,7 +1386,8 @@ capture_user(struct intel_engine_capture_vma *capture,
 	struct i915_capture_list *c;
 
 	for (c = rq->capture_list; c; c = c->next)
-		capture = capture_vma_snapshot(capture, c->vma_snapshot, gfp);
+		capture = capture_vma_snapshot(capture, c->vma_res, gfp,
+					       "user");
 
 	return capture;
 }
@@ -1415,16 +1405,19 @@ static struct i915_vma_coredump *
 create_vma_coredump(const struct intel_gt *gt, struct i915_vma *vma,
 		    const char *name, struct i915_vma_compress *compress)
 {
-	struct i915_vma_coredump *ret;
-	struct i915_vma_snapshot tmp;
+	struct i915_vma_coredump *ret = NULL;
+	struct i915_vma_resource *vma_res;
+	bool lockdep_cookie;
 
 	if (!vma)
 		return NULL;
 
-	GEM_WARN_ON(!i915_vma_is_pinned(vma));
-	i915_vma_snapshot_init_onstack(&tmp, vma, name);
-	ret = i915_vma_coredump_create(gt, &tmp, compress);
-	i915_vma_snapshot_put_onstack(&tmp);
+	vma_res = vma->resource;
+
+	if (i915_vma_resource_hold(vma_res, &lockdep_cookie)) {
+		ret = i915_vma_coredump_create(gt, vma_res, compress, name);
+		i915_vma_resource_unhold(vma_res, lockdep_cookie);
+	}
 
 	return ret;
 }
@@ -1471,7 +1464,7 @@ intel_engine_coredump_add_request(struct intel_engine_coredump *ee,
 	 * as the simplest method to avoid being overwritten
 	 * by userspace.
 	 */
-	vma = capture_vma_snapshot(vma, &rq->batch_snapshot, gfp);
+	vma = capture_vma_snapshot(vma, rq->batch_res, gfp, "batch");
 	vma = capture_user(vma, rq, gfp);
 	vma = capture_vma(vma, rq->ring->vma, "ring", gfp);
 	vma = capture_vma(vma, rq->context->state, "HW context", gfp);
@@ -1492,14 +1485,14 @@ intel_engine_coredump_add_vma(struct intel_engine_coredump *ee,
 
 	while (capture) {
 		struct intel_engine_capture_vma *this = capture;
-		struct i915_vma_snapshot *vsnap = this->vsnap;
+		struct i915_vma_resource *vma_res = this->vma_res;
 
 		add_vma(ee,
-			i915_vma_coredump_create(engine->gt,
-						 vsnap, compress));
+			i915_vma_coredump_create(engine->gt, vma_res,
+						 compress, this->name));
 
-		i915_vma_snapshot_resource_unpin(vsnap, this->lockdep_cookie);
-		i915_vma_snapshot_put(vsnap);
+		i915_vma_resource_unhold(vma_res, this->lockdep_cookie);
+		i915_vma_resource_put(vma_res);
 
 		capture = this->next;
 		kfree(this);

drivers/gpu/drm/i915/i915_request.c

@@ -115,8 +115,10 @@ static void i915_fence_release(struct dma_fence *fence)
 		   rq->guc_prio != GUC_PRIO_FINI);
 
 	i915_request_free_capture_list(fetch_and_zero(&rq->capture_list));
-	if (i915_vma_snapshot_present(&rq->batch_snapshot))
-		i915_vma_snapshot_put_onstack(&rq->batch_snapshot);
+	if (rq->batch_res) {
+		i915_vma_resource_put(rq->batch_res);
+		rq->batch_res = NULL;
+	}
 
 	/*
 	 * The request is put onto a RCU freelist (i.e. the address
@@ -307,7 +309,7 @@ void i915_request_free_capture_list(struct i915_capture_list *capture)
 	while (capture) {
 		struct i915_capture_list *next = capture->next;
 
-		i915_vma_snapshot_put(capture->vma_snapshot);
+		i915_vma_resource_put(capture->vma_res);
 		kfree(capture);
 		capture = next;
 	}
@@ -853,7 +855,7 @@ static void __i915_request_ctor(void *arg)
 	i915_sw_fence_init(&rq->semaphore, semaphore_notify);
 
 	clear_capture_list(rq);
-	rq->batch_snapshot.present = false;
+	rq->batch_res = NULL;
 
 	init_llist_head(&rq->execute_cb);
 }
@@ -959,7 +961,7 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
 	__rq_init_watchdog(rq);
 	assert_capture_list_is_null(rq);
 	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
-	GEM_BUG_ON(i915_vma_snapshot_present(&rq->batch_snapshot));
+	GEM_BUG_ON(rq->batch_res);
 
 	/*
 	 * Reserve space in the ring buffer for all the commands required to

drivers/gpu/drm/i915/i915_request.h

@@ -40,7 +40,7 @@
 #include "i915_scheduler.h"
 #include "i915_selftest.h"
 #include "i915_sw_fence.h"
-#include "i915_vma_snapshot.h"
+#include "i915_vma_resource.h"
 
 #include <uapi/drm/i915_drm.h>
 
@@ -52,7 +52,7 @@ struct i915_request;
 
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
 struct i915_capture_list {
-	struct i915_vma_snapshot *vma_snapshot;
+	struct i915_vma_resource *vma_res;
 	struct i915_capture_list *next;
 };
 
@@ -300,7 +300,7 @@ struct i915_request {
 	/** Batch buffer pointer for selftest internal use. */
 	I915_SELFTEST_DECLARE(struct i915_vma *batch);
 
-	struct i915_vma_snapshot batch_snapshot;
+	struct i915_vma_resource *batch_res;
 
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
 	/**