[CRIU] [RFC PATCH 01/20] criu/parse: Treat some unsupported VMAs as regular

[Felix Kuehling]

From: Rajneesh Bhardwaj <rajneesh.bhardwaj at amd.com>

Unsupported VMAs that provide special plugins for backup can be treated
as regular VMAs and criu should save their metadata in the dump files.
There can be several special backup plugins that might run at different
times during checkpoint and restore.

To checkpoint tasks that have opened AMD KFD/RenderDXXX device files
directly directly or via AMD ROCt library, we can use special plugins
such as kfd_plugin.so or similar that implement various EXT and other
new hooks to support checkpointing and restore.

Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj at amd.com>
Signed-off-by: David Yat Sin <david.yatsin at amd.com>
---
 criu/include/proc_parse.h |  3 +++
 criu/proc_parse.c         | 51 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/criu/include/proc_parse.h b/criu/include/proc_parse.h
index c043804b4..ecddf9015 100644
--- a/criu/include/proc_parse.h
+++ b/criu/include/proc_parse.h
@@ -8,6 +8,9 @@
 #define PROC_TASK_COMM_LEN	32
 #define PROC_TASK_COMM_LEN_FMT	"(%31s"
 
+#define DRM_FIRST_RENDER_NODE 128
+#define DRM_LAST_RENDER_NODE 255
+
 struct proc_pid_stat {
 	int			pid;
 	char			comm[PROC_TASK_COMM_LEN];
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index cb47d6fdd..bf71172cc 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -190,6 +190,7 @@ struct vma_file_info {
 	int dev_min;
 	unsigned long ino;
 	struct vma_area *vma;
+	bool has_special_plugin;
 };
 
 static inline int vfi_equal(struct vma_file_info *a, struct vma_file_info *b)
@@ -592,14 +593,49 @@ static int handle_vma(pid_t pid, struct vma_area *vma_area,
 		}
 	} else if (*vm_file_fd >= 0) {
 		struct stat *st_buf = vma_area->vmst;
+		struct stat st_kfd, st_dri_min;
+		char img_path[128];
+		int ret;
 
 		if (S_ISREG(st_buf->st_mode))
 			/* regular file mapping -- supported */;
 		else if (S_ISCHR(st_buf->st_mode) && (st_buf->st_rdev == DEVZERO))
 			/* devzero mapping -- also makes sense */;
 		else {
-			pr_err("Can't handle non-regular mapping on %d's map %"PRIx64"\n", pid, vma_area->e->start);
-			goto err;
+			ret = stat("/dev/kfd", &st_kfd);
+			if (ret == -1) {
+				pr_perror("fstat error for /dev/kfd\n");
+				goto err;
+			}
+			snprintf(img_path, sizeof(img_path), "/dev/dri/renderD%d",
+				 DRM_FIRST_RENDER_NODE);
+
+			ret = stat(img_path, &st_dri_min);
+			if (ret == -1) {
+				pr_perror("fstat error for %s\n", img_path);
+				goto err;
+			}
+
+			if (major(st_buf->st_rdev) == major(st_kfd.st_rdev) ||
+			    ((major(st_buf->st_rdev) == major(st_dri_min.st_rdev)) &&
+			     (minor(st_buf->st_rdev) >= minor(st_dri_min.st_rdev) &&
+			      minor(st_buf->st_rdev) >= DRM_FIRST_RENDER_NODE) )) {
+				pr_debug("Known non-regular mapping, kfd-renderD%d -> OK\n",
+					 minor(st_buf->st_rdev));
+				pr_debug("AMD KFD(maj) = %d, DRI(maj,min) = %d:%d, "
+					 "VMA Device fd(maj,min) = %d:%d\n",
+					 major(st_kfd.st_rdev),
+					 major(st_dri_min.st_rdev),
+					 minor(st_dri_min.st_rdev),
+					 major(st_buf->st_rdev),
+					 minor(st_buf->st_rdev));
+
+				vfi->has_special_plugin = true;
+
+			} else {
+				pr_err("Can't handle non-regular mapping on %d's map %"PRIx64"\n", pid, vma_area->e->start);
+				goto err;
+			}
 		}
 
 		if (is_anon_shmem_map(st_buf->st_dev) && !strncmp(file_path, "/SYSV", 5)) {
@@ -666,9 +702,16 @@ static int vma_list_add(struct vma_area *vma_area,
 			struct vma_file_info *vfi, struct vma_file_info *prev_vfi)
 {
 	if (vma_area->e->status & VMA_UNSUPP) {
-		pr_err("Unsupported mapping found %016"PRIx64"-%016"PRIx64"\n",
+		if (vfi->has_special_plugin) {
+			pr_debug("Device file mapping %016"PRIx64"-%016"PRIx64" "
+				 "must be supported via special plugins\n",
+				 vma_area->e->start, vma_area->e->end);
+
+		} else {
+			pr_err("Unsupported mapping found %016"PRIx64"-%016"PRIx64"\n",
 					vma_area->e->start, vma_area->e->end);
-		return -1;
+			return -1;
+		}
 	}
 
 	/* Add a guard page only if here is enough space for it */
-- 
2.17.1