[dpdk-dev] [PATCH v4] VFIO: Avoid to enable vfio while the module not loaded

[Michael Qiu <michael.qiu@intel.com>]

When vfio module is not loaded when kernel support vfio feature,
the routine still try to open the container to get file
description.

This action is not safe, and of cause got error messages:

EAL: Detected 40 lcore(s)
EAL:   unsupported IOMMU type!
EAL: VFIO support could not be initialized
EAL: Setting up memory...

This may make user confuse, this patch make it reasonable
and much more soomth to user.

Signed-off-by: Michael Qiu <michael.qiu@intel.com>
---
v4 --> v3:
	1. Remove RTE_LOG for params check
	2. Remove "vfio" module check as "vfio_iommu_type1"
	   loaded indecated "vfio" loaded

v3 --> v2:
        1. Add error log in rte_eal_check_module()
        2. Some code clean up.

v2 --> v1:
        1. Move check_module() from rte_common.h to eal_private.h
           and rename to rte_eal_check_module().
           To make it linuxapp only.
        2. Some code clean up.

 lib/librte_eal/common/eal_private.h        | 42 ++++++++++++++++++++++++++++++
 lib/librte_eal/linuxapp/eal/eal_pci_vfio.c | 29 ++++++++++++++++++---
 2 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index 232fcec..e877a25 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -35,6 +35,9 @@
 #define _EAL_PRIVATE_H_
 
 #include <stdio.h>
+#include <string.h>
+#include <rte_log.h>
+#include <errno.h>
 
 /**
  * Initialize the memzone subsystem (private to eal).
@@ -203,4 +206,43 @@ int rte_eal_alarm_init(void);
  */
 int rte_eal_dev_init(void);
 
+/**
+ * Function is to check if the kernel module(like, vfio, vfio_iommu_type1,
+ * etc.) loaded.
+ *
+ * @param module_name
+ *	The module's name which need to be checked
+ *
+ * @return
+ * 	-1 means some error happens(NULL pointer or open failure)
+ * 	0  means the module not loaded
+ * 	1  means the module loaded
+ */
+static inline int
+rte_eal_check_module(const char *module_name)
+{
+	char mod_name[30]; /* Any module names can be longer than 30 bytes? */
+	int ret = 0;
+
+	if (NULL == module_name)
+		return -1;
+
+	FILE * fd = fopen("/proc/modules", "r");
+	if (NULL == fd) {
+		RTE_LOG(ERR, EAL, "Open /proc/modules failed!"
+			" error %i (%s)\n", errno, strerror(errno));
+		return -1;
+	}
+	while(!feof(fd)) {
+		fscanf(fd, "%s %*[^\n]", mod_name);
+		if(!strcmp(mod_name, module_name)) {
+			ret = 1;
+			break;
+		}
+	}
+	fclose(fd);
+
+	return ret;
+}
+
 #endif /* _EAL_PRIVATE_H_ */
diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
index c1246e8..8c54d2a 100644
--- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
@@ -44,6 +44,7 @@
 #include <rte_tailq.h>
 #include <rte_eal_memconfig.h>
 #include <rte_malloc.h>
+#include <eal_private.h>
 
 #include "eal_filesystem.h"
 #include "eal_pci_init.h"
@@ -339,10 +340,15 @@ pci_vfio_get_container_fd(void)
 		ret = ioctl(vfio_container_fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU);
 		if (ret != 1) {
 			if (ret < 0)
-				RTE_LOG(ERR, EAL, "  could not get IOMMU type, "
-						"error %i (%s)\n", errno, strerror(errno));
+				RTE_LOG(ERR, EAL, "  could not get IOMMU type,"
+					" error %i (%s)\n", errno,
+					strerror(errno));
 			else
-				RTE_LOG(ERR, EAL, "  unsupported IOMMU type!\n");
+				/* Better to show the IOMMU type return from
+				 * kernel for easy debug
+				 */
+				RTE_LOG(ERR, EAL, "  unsupported IOMMU type"
+					" detected: %d in VFIO\n", ret);
 			close(vfio_container_fd);
 			return -1;
 		}
@@ -783,11 +789,28 @@ pci_vfio_enable(void)
 {
 	/* initialize group list */
 	int i;
+	int module_vfio_type1;
 
 	for (i = 0; i < VFIO_MAX_GROUPS; i++) {
 		vfio_cfg.vfio_groups[i].fd = -1;
 		vfio_cfg.vfio_groups[i].group_no = -1;
 	}
+
+	module_vfio_type1 = rte_eal_check_module("vfio_iommu_type1");
+
+	/* return error directly */
+	if (module_vfio_type1 == -1) {
+		RTE_LOG(INFO, EAL, "Could not get loaded module details!\n");
+		return -1;
+	}
+
+	/* return 0 if VFIO modules not loaded */
+	if (module_vfio_type1 == 0) {
+		RTE_LOG(INFO, EAL, "VFIO modules not all loaded,"
+			" skip VFIO support ...\n");
+		return 0;
+	}
+
 	vfio_cfg.vfio_container_fd = pci_vfio_get_container_fd();
 
 	/* check if we have VFIO driver enabled */
-- 
1.9.3