From: Matthew Wilcox <willy@infradead.org>
Date: Tue, 23 Oct 2018 18:36:36 +0000 (-0400)
Subject: drm/i915: Convert spt_tree to XArray
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=edc671dc6483dbccf4e54e99d73c578998575ac8;p=users%2Fwilly%2Fxarray.git

drm/i915: Convert spt_tree to XArray

A straightforward conversion.  Notice the XArray does not suffer from
exposing the RCU problem to its users like the radix tree did.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 4b04af569c05c..87a77bad6e6da 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -741,7 +741,7 @@ static void ppgtt_free_spt(struct intel_vgpu_ppgtt_spt *spt)
 	dma_unmap_page(kdev, spt->shadow_page.mfn << I915_GTT_PAGE_SHIFT, 4096,
 		       PCI_DMA_BIDIRECTIONAL);
 
-	radix_tree_delete(&spt->vgpu->gtt.spt_tree, spt->shadow_page.mfn);
+	xa_erase(&spt->vgpu->gtt.spts, spt->shadow_page.mfn);
 
 	if (spt->guest_page.gfn) {
 		if (spt->guest_page.oos_page)
@@ -756,19 +756,10 @@ static void ppgtt_free_spt(struct intel_vgpu_ppgtt_spt *spt)
 
 static void ppgtt_free_all_spt(struct intel_vgpu *vgpu)
 {
-	struct intel_vgpu_ppgtt_spt *spt, *spn;
-	struct radix_tree_iter iter;
-	LIST_HEAD(all_spt);
-	void __rcu **slot;
-
-	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &vgpu->gtt.spt_tree, &iter, 0) {
-		spt = radix_tree_deref_slot(slot);
-		list_move(&spt->post_shadow_list, &all_spt);
-	}
-	rcu_read_unlock();
+	struct intel_vgpu_ppgtt_spt *spt;
+	unsigned long index;
 
-	list_for_each_entry_safe(spt, spn, &all_spt, post_shadow_list)
+	xa_for_each(&vgpu->gtt.spts, index, spt)
 		ppgtt_free_spt(spt);
 }
 
@@ -810,7 +801,7 @@ static struct intel_vgpu_ppgtt_spt *intel_vgpu_find_spt_by_gfn(
 static inline struct intel_vgpu_ppgtt_spt *intel_vgpu_find_spt_by_mfn(
 		struct intel_vgpu *vgpu, unsigned long mfn)
 {
-	return radix_tree_lookup(&vgpu->gtt.spt_tree, mfn);
+	return xa_load(&vgpu->gtt.spts, mfn);
 }
 
 static int reclaim_one_ppgtt_mm(struct intel_gvt *gvt);
@@ -852,13 +843,13 @@ retry:
 	spt->shadow_page.vaddr = page_address(spt->shadow_page.page);
 	spt->shadow_page.mfn = daddr >> I915_GTT_PAGE_SHIFT;
 
-	ret = radix_tree_insert(&vgpu->gtt.spt_tree, spt->shadow_page.mfn, spt);
-	if (ret)
+	if (xa_store(&vgpu->gtt.spts, spt->shadow_page.mfn, spt, GFP_KERNEL))
 		goto err_unmap_dma;
 
 	return spt;
 
 err_unmap_dma:
+	ret = -ENOMEM;
 	dma_unmap_page(kdev, daddr, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
 err_free_spt:
 	free_spt(spt);
@@ -2454,7 +2445,7 @@ int intel_vgpu_init_gtt(struct intel_vgpu *vgpu)
 {
 	struct intel_vgpu_gtt *gtt = &vgpu->gtt;
 
-	INIT_RADIX_TREE(&gtt->spt_tree, GFP_KERNEL);
+	xa_init(&gtt->spts);
 
 	INIT_LIST_HEAD(&gtt->ppgtt_mm_list_head);
 	INIT_LIST_HEAD(&gtt->oos_page_list_head);
@@ -2486,7 +2477,7 @@ static void intel_vgpu_destroy_all_ppgtt_mm(struct intel_vgpu *vgpu)
 	if (GEM_WARN_ON(!list_empty(&vgpu->gtt.ppgtt_mm_list_head)))
 		gvt_err("vgpu ppgtt mm is not fully destroyed\n");
 
-	if (GEM_WARN_ON(!radix_tree_empty(&vgpu->gtt.spt_tree))) {
+	if (GEM_WARN_ON(!xa_empty(&vgpu->gtt.spts))) {
 		gvt_err("Why we still has spt not freed?\n");
 		ppgtt_free_all_spt(vgpu);
 	}
diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
index 42d0394f0de2b..b5834a13c599a 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.h
+++ b/drivers/gpu/drm/i915/gvt/gtt.h
@@ -199,7 +199,7 @@ struct intel_vgpu_gtt {
 	struct intel_vgpu_mm *ggtt_mm;
 	unsigned long active_ppgtt_mm_bitmap;
 	struct list_head ppgtt_mm_list_head;
-	struct radix_tree_root spt_tree;
+	struct xarray spts;
 	struct list_head oos_page_list_head;
 	struct list_head post_shadow_list_head;
 	struct intel_vgpu_scratch_pt scratch_pt[GTT_TYPE_MAX];
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index fe7a6ec2c199c..4998250bb2aaa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -46,6 +46,7 @@
 #include <linux/reservation.h>
 #include <linux/shmem_fs.h>
 #include <linux/stackdepot.h>
+#include <linux/xarray.h>
 
 #include <drm/intel-gtt.h>
 #include <drm/drm_legacy.h> /* for struct drm_dma_handle */