Re: [dpdk-dev] [PATCH v2] VFIO: Avoid to enable vfio while the module not loaded

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

Hi Michael,

Few nitpicks :-) (wording of the log message I guess is up to Thomas, I won't comment on that)

>  lib/librte_eal/common/eal_private.h        | 36
> ++++++++++++++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_pci_vfio.c | 24 +++++++++++++++++---
>  2 files changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_eal/common/eal_private.h
> b/lib/librte_eal/common/eal_private.h
> index 232fcec..e741bdb 100644
> --- a/lib/librte_eal/common/eal_private.h
> +++ b/lib/librte_eal/common/eal_private.h
> @@ -35,6 +35,7 @@
>  #define _EAL_PRIVATE_H_
> 
>  #include <stdio.h>
> +#include <string.h>
> 
>  /**
>   * Initialize the memzone subsystem (private to eal).
> @@ -203,4 +204,39 @@ 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 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 (fd == NULL)
> +		return -1;

Can we add RTE_LOG statement here, with an strerror(errno) like in other places? Fopen failed, we should at least know why :-)

> +	while(!feof(fd)) {
> +		fscanf(fd, "%s %*[^\n]", mod_name);
> +		if(!strcmp(mod_name, module_name)) {

Probably should use strncmp instead of strcmp.

> +			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..52ab2d0 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 +340,13 @@ 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! "
> +					"expect: VFIO_TYPE1_IOMMU, "
> +					"actual: %d\n", ret);

I'm not even sure we need this "expected" bit at all. We don't get back the IOMMU type VFIO currently supports; rather, this code checks if VFIO's support for VFIO_TYPE1_IOMMU is enabled or not. So I would change the error message to something more descriptive, such as " required IOMMU type support not present in VFIO!\n", and get rid of the "expected".

>  			close(vfio_container_fd);
>  			return -1;
>  		}
> @@ -788,6 +792,20 @@ pci_vfio_enable(void)
>  		vfio_cfg.vfio_groups[i].fd = -1;
>  		vfio_cfg.vfio_groups[i].group_no = -1;
>  	}
> +
> +	/* return error directly */
> +	if (rte_eal_check_module("vfio") == -1 ||
> +	    rte_eal_check_module("vfio_iommu_type1") == -1)
> +		return -1;
> +
> +	/* return 0 if not all VFIO modules loaded */
> +	if (rte_eal_check_module("vfio") == 0 ||
> +	    rte_eal_check_module("vfio_iommu_type1") == 0) {
> +		RTE_LOG(INFO, EAL, "VFIO modules not all loaded,"
> +			" skip VFIO support ...\n");
> +		return 0;
> +	}

Can we perhaps make one call per module instead of two? i.e. something like:

int vfio_ret, vfio_ type1_ret;
vfio_ret = rte_eal_check_module("vfio");
vfio_type1_ret = rte_eal_check_module("vfio_iommu_type1");

if (vfio_ret == -1 || vfio_type1_ret == -1)
    return -1;
else if (vfio_ret == 0 || vfio_type1_ret == 0) {
     ....
    return 0;
}

> +
>  	vfio_cfg.vfio_container_fd = pci_vfio_get_container_fd();
> 
>  	/* check if we have VFIO driver enabled */
> --
> 1.9.3