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

On Tue, Jan 19, 2016 at 7:48 PM, Burakov, Anatoly
[off-list ref] wrote:

Hi Santosh,

quoted

+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