[PATCH v3 3/4] dma-mapping: benchmark: add support for dma_map_sg

[Qinxin Xia <xiaqinxin@huawei.com>]

Support for dma scatter-gather mapping and is intended for testing
mapping performance. It achieves by introducing the dma_sg_map_param
structure and related functions, which enable the implementation of
scatter-gather mapping preparation, mapping, and unmapping operations.
Additionally, the dma_map_benchmark_ops array is updated to include
operations for scatter-gather mapping. This commit aims to provide
a wider range of mapping performance test to cater to different scenarios.

Signed-off-by: Qinxin Xia <xiaqinxin@huawei.com>
---
 include/linux/map_benchmark.h |  43 ++++++++++----
 kernel/dma/map_benchmark.c    | 103 ++++++++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+), 12 deletions(-)

diff --git a/include/linux/map_benchmark.h b/include/linux/map_benchmark.h
index 5294dfd1870f..bf8c9ade43fd 100644
--- a/include/linux/map_benchmark.h
+++ b/include/linux/map_benchmark.h
@@ -17,22 +17,41 @@
 
 enum {
 	DMA_MAP_SINGLE_MODE,
+	DMA_MAP_SG_MODE,
 	DMA_MAP_MODE_MAX
 };
 
+/**
+ * struct map_benchmark - Benchmarking data for DMA mapping operations.
+ * @avg_map_100ns: Average map latency in 100ns.
+ * @map_stddev: Standard deviation of map latency.
+ * @avg_unmap_100ns: Average unmap latency in 100ns.
+ * @unmap_stddev: Standard deviation of unmap latency.
+ * @threads: Number of threads performing map/unmap operations in parallel.
+ * @seconds: Duration of the test in seconds.
+ * @node: NUMA node on which this benchmark will run.
+ * @dma_bits: DMA addressing capability.
+ * @dma_dir: DMA data direction.
+ * @dma_trans_ns: Time for DMA transmission in ns.
+ * @granule: Number of PAGE_SIZE units to map/unmap at once.
+	     In SG mode, this represents the number of scatterlist entries.
+	     In single mode, this represents the total size of the mapping.
+ * @map_mode: Mode of DMA mapping.
+ * @expansion: Reserved for future use.
+ */
 struct map_benchmark {
-	__u64 avg_map_100ns; /* average map latency in 100ns */
-	__u64 map_stddev; /* standard deviation of map latency */
-	__u64 avg_unmap_100ns; /* as above */
+	__u64 avg_map_100ns;
+	__u64 map_stddev;
+	__u64 avg_unmap_100ns;
 	__u64 unmap_stddev;
-	__u32 threads; /* how many threads will do map/unmap in parallel */
-	__u32 seconds; /* how long the test will last */
-	__s32 node; /* which numa node this benchmark will run on */
-	__u32 dma_bits; /* DMA addressing capability */
-	__u32 dma_dir; /* DMA data direction */
-	__u32 dma_trans_ns; /* time for DMA transmission in ns */
-	__u32 granule;  /* how many PAGE_SIZE will do map/unmap once a time */
-	__u8  map_mode; /* the mode of dma map */
-	__u8 expansion[75];     /* For future use */
+	__u32 threads;
+	__u32 seconds;
+	__s32 node;
+	__u32 dma_bits;
+	__u32 dma_dir;
+	__u32 dma_trans_ns;
+	__u32 granule;
+	__u8  map_mode;
+	__u8 expansion[75];
 };
 #endif /* _KERNEL_DMA_BENCHMARK_H */
diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
index 47a06b891db8..3a996be9fb22 100644
--- a/kernel/dma/map_benchmark.c
+++ b/kernel/dma/map_benchmark.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/timekeeping.h>
 
@@ -111,8 +112,110 @@ static struct map_benchmark_ops dma_single_map_benchmark_ops = {
 	.do_unmap = dma_single_map_benchmark_do_unmap,
 };
 
+struct dma_sg_map_param {
+	struct sg_table sgt;
+	struct device *dev;
+	void **buf;
+	u32 npages;
+	u32 dma_dir;
+};
+
+static void *dma_sg_map_benchmark_prepare(struct map_benchmark_data *map)
+{
+	struct scatterlist *sg;
+	int i;
+
+	struct dma_sg_map_param *params __free(kfree) = kzalloc(sizeof(*params), GFP_KERNEL);
+	if (!params)
+		return NULL;
+
+	/*
+	 * Set the number of scatterlist entries based on the granule.
+	 * In SG mode, 'granule' represents the number of scatterlist entries.
+	 * Each scatterlist entry corresponds to a single page.
+	 */
+	params->npages = map->bparam.granule;
+	params->dma_dir = map->bparam.dma_dir;
+	params->dev = map->dev;
+	params->buf = kmalloc_array(params->npages, sizeof(*params->buf),
+				    GFP_KERNEL);
+	if (!params->buf)
+		goto out;
+
+	if (sg_alloc_table(&params->sgt, params->npages, GFP_KERNEL))
+		goto free_buf;
+
+	for_each_sgtable_sg(&params->sgt, sg, i) {
+		params->buf[i] = (void *)__get_free_page(GFP_KERNEL);
+		if (!params->buf[i])
+			goto free_page;
+
+		if (params->dma_dir != DMA_FROM_DEVICE)
+			memset(params->buf[i], 0x66, PAGE_SIZE);
+
+		sg_set_buf(sg, params->buf[i], PAGE_SIZE);
+	}
+
+	return_ptr(params);
+
+free_page:
+	while (i-- > 0)
+		free_page((unsigned long)params->buf[i]);
+
+	sg_free_table(&params->sgt);
+free_buf:
+	kfree(params->buf);
+out:
+	return NULL;
+}
+
+static void dma_sg_map_benchmark_unprepare(void *mparam)
+{
+	struct dma_sg_map_param *params = mparam;
+	int i;
+
+	for (i = 0; i < params->npages; i++)
+		free_page((unsigned long)params->buf[i]);
+
+	sg_free_table(&params->sgt);
+
+	kfree(params->buf);
+	kfree(params);
+}
+
+static int dma_sg_map_benchmark_do_map(void *mparam)
+{
+	struct dma_sg_map_param *params = mparam;
+	int ret = 0;
+
+	int sg_mapped = dma_map_sg(params->dev, params->sgt.sgl,
+				   params->npages, params->dma_dir);
+	if (!sg_mapped) {
+		pr_err("dma_map_sg failed on %s\n", dev_name(params->dev));
+		ret = -ENOMEM;
+	}
+
+	return ret;
+}
+
+static void dma_sg_map_benchmark_do_unmap(void *mparam)
+{
+	struct dma_sg_map_param *params = mparam;
+
+	dma_unmap_sg(params->dev, params->sgt.sgl, params->npages,
+		     params->dma_dir);
+}
+
+static struct map_benchmark_ops dma_sg_map_benchmark_ops = {
+	.prepare = dma_sg_map_benchmark_prepare,
+	.unprepare = dma_sg_map_benchmark_unprepare,
+	.do_map = dma_sg_map_benchmark_do_map,
+	.do_unmap = dma_sg_map_benchmark_do_unmap,
+};
+
 static struct map_benchmark_ops *dma_map_benchmark_ops[DMA_MAP_MODE_MAX] = {
 	[DMA_MAP_SINGLE_MODE] = &dma_single_map_benchmark_ops,
+	[DMA_MAP_SG_MODE] = &dma_sg_map_benchmark_ops,
 };
 
 static int map_benchmark_thread(void *data)
-- 
2.33.0