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

["Xie, Huawei" <huawei.xie@intel.com>]

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