Re: [dpdk-dev] [PATCH v5 08/11] eal: pci: introduce RTE_KDRV_VFIO_NOIOMMUi driver mode

[Santosh Shukla <sshukla@mvista.com>]

On Tue, Jan 19, 2016 at 7:48 PM, Burakov, Anatoly
<anatoly.burakov@intel.com> wrote:
> Hi Santosh,
>
>> +int
>> +pci_vfio_is_noiommu(struct rte_pci_device *pci_dev) {
>> +     FILE *fp;
>> +     struct rte_pci_addr *loc;
>> +     const char *path =
>> "/sys/module/vfio/parameters/enable_unsafe_noiommu_mode";
>> +     char filename[PATH_MAX] = {0};
>> +     char buf[PATH_MAX] = {0};
>> +
>> +     /*
>> +      * 1. chk vfio-noiommu mode set in kernel driver
>> +      * 2. verify pci device attached to vfio-noiommu driver
>> +      * example:
>> +      * cd /sys/bus/pci/drivers/vfio-pci/<virtio_dev_addr>/iommu_group
>> +      * > cat name
>> +      * > vfio-noiommu --> means virtio_dev attached to vfio-noiommu
>> driver
>> +      */
>> +
>> +     fp = fopen(path, "r");
>> +     if (fp == NULL) {
>> +             RTE_LOG(ERR, EAL, "can't open %s\n", path);
>> +             return -1;
>> +     }
>> +
>> +     if (fread(buf, sizeof(char), 1, fp) != 1) {
>> +             RTE_LOG(ERR, EAL, "can't read from file %s\n", path);
>> +             fclose(fp);
>> +             return -1;
>> +     }
>> +
>> +     if (strncmp(buf, "Y", 1) != 0) {
>> +             RTE_LOG(ERR, EAL, "[%s]: vfio: noiommu mode not set\n",
>> path);
>> +             fclose(fp);
>> +             return -1;
>> +     }
>> +
>> +     fclose(fp);
>> +
>> +     /* 2. chk whether attached driver is vfio-noiommu or not */
>> +     loc = &pci_dev->addr;
>> +     snprintf(filename, sizeof(filename),
>> +                  SYSFS_PCI_DEVICES "/" PCI_PRI_FMT
>> "/iommu_group/name",
>> +                  loc->domain, loc->bus, loc->devid, loc->function);
>> +
>> +     /* check for vfio-noiommu */
>> +     fp = fopen(filename, "r");
>> +     if (fp == NULL) {
>> +             RTE_LOG(ERR, EAL, "can't open %s\n", filename);
>> +             return -1;
>> +     }
>> +
>> +     if (fread(buf, sizeof(char), sizeof("vfio-noiommu"), fp) !=
>> +               sizeof("vfio-noiommu")) {
>> +             RTE_LOG(ERR, EAL, "can't read from file %s\n", filename);
>> +             fclose(fp);
>> +             return -1;
>> +     }
>> +
>> +     if (strncmp(buf, "vfio-noiommu", strlen("vfio-noiommu")) != 0) {
>> +             RTE_LOG(ERR, EAL, "not a vfio-noiommu driver\n");
>> +             fclose(fp);
>> +             return -1;
>> +     }
>> +
>> +     fclose(fp);
>> +
>> +     return 0;
>> +}
>
> Since this is a public non-performance critical API, shouldn't we check if pci_dev is NULL? Otherwise the patch-set seems fine to me as far as VFIO parts are concerned.
>
pci_scan_one() uses this api for now and it populate pci_dev before
pci_vfio_is_noiommu() could use. So didn't though to add a check, But
you are right in case any other module want to use this api. Sending
patch now. Thanks.

> Thanks,
> Anatoly