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

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

On 2014/12/8 20:19, Burakov, Anatoly wrote:
>> 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;
>> +}
>> +
> Apologies for not bringing this up before, but do we really want the rte_eal_check_module inline in the header? I think it would be better to declare it in eal_private but move the definition into eal.c.

No need, actually, I'm very appreciate that you can spend your time to
review my patch again and again. I really want to say thank you to you.

For rte_eal_check_module inline in the header, it really no need stay in
header, so ugly. I will make new version of it, and re-post.

 
>>  #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);
> I'm not sure this message is meaningful. That ioctl call can either -1, 0 or 1. We already handle 1 separately; -1 means an error; 0 means IOMMU type 1 is not supported. The return value will *not* indicate which IOMMU types *are* currently supported - it will only indicate that the IOMMU type you requested is not supported. So there's really no point in indicating the return value in case of ret 0 - it is best to just mention that requested IOMMU type support is not enabled in VFIO.

Yes, you are right, I make a mistake.

>
>>  			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
>