linux-kernel - [PATCH v3 31/33] drm/msm: Split out map/unmap ops

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Message-ID: <20250428205619.227835-32-robdclark@gmail.com>
Date: Mon, 28 Apr 2025 13:54:38 -0700
From: Rob Clark <robdclark@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: freedreno@...ts.freedesktop.org,
	linux-arm-msm@...r.kernel.org,
	Connor Abbott <cwabbott0@...il.com>,
	Rob Clark <robdclark@...omium.org>,
	Rob Clark <robdclark@...il.com>,
	Abhinav Kumar <quic_abhinavk@...cinc.com>,
	Dmitry Baryshkov <lumag@...nel.org>,
	Sean Paul <sean@...rly.run>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v3 31/33] drm/msm: Split out map/unmap ops

From: Rob Clark <robdclark@...omium.org>

With async VM_BIND, the actual pgtable updates are deferred.
Synchronously, a list of map/unmap ops will be generated, but the
actual pgtable changes are deferred.  To support that, split out
op handlers and change the existing non-VM_BIND paths to use them.

Note in particular, the vma itself may already be destroyed/freed
by the time an UNMAP op runs (or even a MAP op if there is a later
queued UNMAP).  For this reason, the op handlers cannot reference
the vma pointer.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_gem_vma.c | 63 +++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_vma.c b/drivers/gpu/drm/msm/msm_gem_vma.c
index 5b8769e152c9..f3903825e0b6 100644
--- a/drivers/gpu/drm/msm/msm_gem_vma.c
+++ b/drivers/gpu/drm/msm/msm_gem_vma.c
@@ -8,6 +8,34 @@
 #include "msm_gem.h"
 #include "msm_mmu.h"
 
+#define vm_dbg(fmt, ...) pr_debug("%s:%d: "fmt"\n", __func__, __LINE__, ##__VA_ARGS__)
+
+/**
+ * struct msm_vm_map_op - create new pgtable mapping
+ */
+struct msm_vm_map_op {
+	/** @iova: start address for mapping */
+	uint64_t iova;
+	/** @range: size of the region to map */
+	uint64_t range;
+	/** @offset: offset into @sgt to map */
+	uint64_t offset;
+	/** @sgt: pages to map, or NULL for a PRR mapping */
+	struct sg_table *sgt;
+	/** @prot: the mapping protection flags */
+	int prot;
+};
+
+/**
+ * struct msm_vm_unmap_op - unmap a range of pages from pgtable
+ */
+struct msm_vm_unmap_op {
+	/** @iova: start address for unmap */
+	uint64_t iova;
+	/** @range: size of region to unmap */
+	uint64_t range;
+};
+
 static void
 msm_gem_vm_free(struct drm_gpuvm *gpuvm)
 {
@@ -21,28 +49,45 @@ msm_gem_vm_free(struct drm_gpuvm *gpuvm)
 	kfree(vm);
 }
 
+static void
+vm_unmap_op(struct msm_gem_vm *vm, const struct msm_vm_unmap_op *op)
+{
+	vm_dbg("%p: %016llx %016llx", vm, op->iova, op->iova + op->range);
+
+	vm->mmu->funcs->unmap(vm->mmu, op->iova, op->range);
+}
+
 /* Actually unmap memory for the vma */
 void msm_gem_vma_unmap(struct drm_gpuva *vma)
 {
 	struct msm_gem_vma *msm_vma = to_msm_vma(vma);
-	struct msm_gem_vm *vm = to_msm_vm(vma->vm);
-	unsigned size = vma->va.range;
 
 	/* Don't do anything if the memory isn't mapped */
 	if (!msm_vma->mapped)
 		return;
 
-	vm->mmu->funcs->unmap(vm->mmu, vma->va.addr, size);
+	vm_unmap_op(to_msm_vm(vma->vm), &(struct msm_vm_unmap_op){
+		.iova = vma->va.addr,
+		.range = vma->va.range,
+	});
 
 	msm_vma->mapped = false;
 }
 
+static int
+vm_map_op(struct msm_gem_vm *vm, const struct msm_vm_map_op *op)
+{
+	vm_dbg("%p: %016llx %016llx", vm, op->iova, op->iova + op->range);
+
+	return vm->mmu->funcs->map(vm->mmu, op->iova, op->sgt, op->offset,
+				   op->range, op->prot);
+}
+
 /* Map and pin vma: */
 int
 msm_gem_vma_map(struct drm_gpuva *vma, int prot, struct sg_table *sgt)
 {
 	struct msm_gem_vma *msm_vma = to_msm_vma(vma);
-	struct msm_gem_vm *vm = to_msm_vm(vma->vm);
 	int ret;
 
 	if (GEM_WARN_ON(!vma->va.addr))
@@ -62,9 +107,13 @@ msm_gem_vma_map(struct drm_gpuva *vma, int prot, struct sg_table *sgt)
 	 * Revisit this if we can come up with a scheme to pre-alloc pages
 	 * for the pgtable in map/unmap ops.
 	 */
-	ret = vm->mmu->funcs->map(vm->mmu, vma->va.addr, sgt,
-				  vma->gem.offset, vma->va.range,
-				  prot);
+	ret = vm_map_op(to_msm_vm(vma->vm), &(struct msm_vm_map_op){
+		.iova = vma->va.addr,
+		.range = vma->va.range,
+		.offset = vma->gem.offset,
+		.sgt = sgt,
+		.prot = prot,
+	});
 	if (ret) {
 		msm_vma->mapped = false;
 	}
-- 
2.49.0