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

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

On 12/10/2014 8:17 AM, Xie, Huawei wrote:
> Hi Michael:
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Qiu, Michael
>> Sent: Monday, December 08, 2014 8:28 AM
>> To: Burakov, Anatoly; dev@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH v4] VFIO: Avoid to enable vfio while the module
>> not loaded
>>
>> 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);
> I see it is already discussed in the other mail that we could limit the count to avoid overflow.
> I don't understand why you don't apply it here.


Yes, I have reply in this thread with below:
  fscanf(fd, "%30s %*[^\n]", mod_name);

> There are already several existing modules that has 20+ length. 

Yes, would you think 30 length is enough? Otherwise I need to increase
the length

Thanks,
Michael
>>>> +		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
>