[PATCH v2] gpudev: pin GPU memory

[<eagostini@nvidia.com>]

From: Elena Agostini <eagostini@nvidia.com>

Enable the possibility to make a GPU memory area accessible from
the CPU.

GPU memory has to be allocated via rte_gpu_mem_alloc().

This patch allows the gpudev library to pin, through the GPU driver,
a chunk of GPU memory and to return a memory pointer usable
by the CPU to access the GPU memory area.

Signed-off-by: Elena Agostini <eagostini@nvidia.com>
---
 lib/gpudev/gpudev.c        | 47 +++++++++++++++++++++++++++++++++++
 lib/gpudev/gpudev_driver.h |  6 +++++
 lib/gpudev/rte_gpudev.h    | 50 ++++++++++++++++++++++++++++++++++++++
 lib/gpudev/version.map     |  2 ++
 4 files changed, 105 insertions(+)

diff --git a/lib/gpudev/gpudev.c b/lib/gpudev/gpudev.c
index 9ae36dbae9..ca627e44b3 100644
--- a/lib/gpudev/gpudev.c
+++ b/lib/gpudev/gpudev.c
@@ -634,6 +634,53 @@ rte_gpu_mem_unregister(int16_t dev_id, void *ptr)
 	return GPU_DRV_RET(dev->ops.mem_unregister(dev, ptr));
 }
 
+int
+rte_gpu_mem_pin(int16_t dev_id, size_t size, void *ptr)
+{
+	struct rte_gpu *dev;
+
+	dev = gpu_get_by_id(dev_id);
+	if (dev == NULL) {
+		GPU_LOG(ERR, "pin mem for invalid device ID %d", dev_id);
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
+
+	if (dev->ops.mem_pin == NULL) {
+		GPU_LOG(ERR, "mem pinning not supported");
+		rte_errno = ENOTSUP;
+		return -rte_errno;
+	}
+
+	if (ptr == NULL || size == 0) /* dry-run  */
+		return 0;
+
+	return GPU_DRV_RET(dev->ops.mem_pin(dev, size, ptr));
+}
+
+int
+rte_gpu_mem_unpin(int16_t dev_id, void *ptr)
+{
+	struct rte_gpu *dev;
+
+	dev = gpu_get_by_id(dev_id);
+	if (dev == NULL) {
+		GPU_LOG(ERR, "unpin mem for invalid device ID %d", dev_id);
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
+
+	if (dev->ops.mem_unpin == NULL) {
+		rte_errno = ENOTSUP;
+		return -rte_errno;
+	}
+
+	if (ptr == NULL) /* dry-run */
+		return 0;
+
+	return GPU_DRV_RET(dev->ops.mem_unpin(dev, ptr));
+}
+
 int
 rte_gpu_wmb(int16_t dev_id)
 {
diff --git a/lib/gpudev/gpudev_driver.h b/lib/gpudev/gpudev_driver.h
index cb7b101f2f..13dd8dac43 100644
--- a/lib/gpudev/gpudev_driver.h
+++ b/lib/gpudev/gpudev_driver.h
@@ -31,6 +31,8 @@ typedef int (rte_gpu_mem_alloc_t)(struct rte_gpu *dev, size_t size, void **ptr);
 typedef int (rte_gpu_mem_free_t)(struct rte_gpu *dev, void *ptr);
 typedef int (rte_gpu_mem_register_t)(struct rte_gpu *dev, size_t size, void *ptr);
 typedef int (rte_gpu_mem_unregister_t)(struct rte_gpu *dev, void *ptr);
+typedef int (rte_gpu_mem_pin_t)(struct rte_gpu *dev, size_t size, void *ptr);
+typedef int (rte_gpu_mem_unpin_t)(struct rte_gpu *dev, void *ptr);
 typedef int (rte_gpu_wmb_t)(struct rte_gpu *dev);
 
 struct rte_gpu_ops {
@@ -46,6 +48,10 @@ struct rte_gpu_ops {
 	rte_gpu_mem_register_t *mem_register;
 	/* Unregister CPU memory from device. */
 	rte_gpu_mem_unregister_t *mem_unregister;
+	/* Pin GPU memory. */
+	rte_gpu_mem_pin_t *mem_pin;
+	/* Unpin GPU memory. */
+	rte_gpu_mem_unpin_t *mem_unpin;
 	/* Enforce GPU write memory barrier. */
 	rte_gpu_wmb_t *wmb;
 };
diff --git a/lib/gpudev/rte_gpudev.h b/lib/gpudev/rte_gpudev.h
index fa3f3aad4f..0a9033c6e0 100644
--- a/lib/gpudev/rte_gpudev.h
+++ b/lib/gpudev/rte_gpudev.h
@@ -447,6 +447,56 @@ int rte_gpu_mem_register(int16_t dev_id, size_t size, void *ptr);
 __rte_experimental
 int rte_gpu_mem_unregister(int16_t dev_id, void *ptr);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Pin a chunk of GPU memory to make it accessible from the CPU
+ * using the memory pointer returned by the function.
+ * GPU memory has to be allocated via rte_gpu_mem_alloc().
+ *
+ * @param dev_id
+ *   Device ID requiring pinned memory.
+ * @param size
+ *   Number of bytes to pin.
+ *   Requesting 0 will do nothing.
+ * @param ptr
+ *   Pointer to the GPU memory area to be pinned.
+ *   NULL is a no-op accepted value.
+
+ * @return
+ *   A pointer to the pinned GPU memory usable by the CPU, otherwise NULL and rte_errno is set:
+ *   - ENODEV if invalid dev_id
+ *   - EINVAL if reserved flags
+ *   - ENOTSUP if operation not supported by the driver
+ *   - E2BIG if size is higher than limit
+ *   - ENOMEM if out of space
+ *   - EPERM if driver error
+ */
+__rte_experimental
+int rte_gpu_mem_pin(int16_t dev_id, size_t size, void *ptr);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Unpin a chunk of GPU memory previously pinned with rte_gpu_mem_pin()
+ *
+ * @param dev_id
+ *   Reference device ID.
+ * @param ptr
+ *   Pointer to the memory area to be unpinned.
+ *   NULL is a no-op accepted value.
+ *
+ * @return
+ *   0 on success, -rte_errno otherwise:
+ *   - ENODEV if invalid dev_id
+ *   - ENOTSUP if operation not supported by the driver
+ *   - EPERM if driver error
+ */
+__rte_experimental
+int rte_gpu_mem_unpin(int16_t dev_id, void *ptr);
+
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
diff --git a/lib/gpudev/version.map b/lib/gpudev/version.map
index 2e414c65cc..8fb0f4623b 100644
--- a/lib/gpudev/version.map
+++ b/lib/gpudev/version.map
@@ -21,7 +21,9 @@ EXPERIMENTAL {
 	rte_gpu_is_valid;
 	rte_gpu_mem_alloc;
 	rte_gpu_mem_free;
+	rte_gpu_mem_pin;
 	rte_gpu_mem_register;
+	rte_gpu_mem_unpin;
 	rte_gpu_mem_unregister;
 	rte_gpu_wmb;
 };
-- 
2.17.1