Re: [dpdk-dev] [PATCH v5] VFIO: Avoid to enable vfio while the module not loaded

["Burakov, Anatoly" <anatoly.burakov@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>
> ---
>  v5 --> v4
> 	1. Move rte_eal_check_module() body to eal.c
> 	2. Clean up "unsupported IOMMU type" log
> 
> 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        | 15 +++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal.c          | 27 +++++++++++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_pci_vfio.c | 26
> +++++++++++++++++++++++---
>  3 files changed, 65 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_eal/common/eal_private.h
> b/lib/librte_eal/common/eal_private.h
> index 232fcec..4183b54 100644
> --- a/lib/librte_eal/common/eal_private.h
> +++ b/lib/librte_eal/common/eal_private.h
> @@ -203,4 +203,19 @@ 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
> + */
> +inline int
> +rte_eal_check_module(const char *module_name);

Just curious - why inline?

> +
>  #endif /* _EAL_PRIVATE_H_ */
> diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
> index 89f3b5e..40b462e 100644
> --- a/lib/librte_eal/linuxapp/eal/eal.c
> +++ b/lib/librte_eal/linuxapp/eal/eal.c
> @@ -859,3 +859,30 @@ int rte_eal_has_hugepages(void)  {
>  	return ! internal_config.no_hugetlbfs;  }
> +
> +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, "%30s %*[^\n]", mod_name);

As far as I know, in fscanf terms, %30s will result in at most 30 character string, i.e. 31 bytes (30 characters + null terminator). So it probably should be %29s.

> +		if(!strcmp(mod_name, module_name)) {
> +			ret = 1;
> +			break;
> +		}
> +	}
> +	fclose(fd);
> +
> +	return ret;
> +}
> diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> index c1246e8..16fe10f 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 +340,12 @@ 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");
> +				RTE_LOG(ERR, EAL, "  unsupported IOMMU
> type"
> +					" detected in VFIO\n");
>  			close(vfio_container_fd);
>  			return -1;
>  		}
> @@ -783,11 +786,28 @@ 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