bus/pci: support IOVA as VA on PowerNV systems

All recent POWER systems, Power 8 and 9 specifically, support an IOMMU
(it can't be disabled). The functionality of the IOMMU is different
depending on whether it's running on a bare metal PowerNV system or in
a virtual environment (PowerVM LPAR or KVM/QEMU).  DPDK currently
supports the IOMMU found on PowerNV platforms, sPAPRv2, so IOVA=VA
mode can be enabled when the correct platform is detected.

The POWER IOMMU type can't be detected through mechanisms such as
parsing files in the /sys hierarchy like x86_64 systems so the
/proc/cpuinfo file is parsed to determine whether Linux is running
on bare metal (i.e. PowerNV) or in a virtual environment (KVM/QEMU).

Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index 71b0a30..ca783b1 100644 (file)
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -554,7 +554,40 @@ pci_device_iommu_support_va(const struct rte_pci_device *dev)
 bool
 pci_device_iommu_support_va(__rte_unused const struct rte_pci_device *dev)
 {
-       return false;
+       /*
+        * IOMMU is always present on a PowerNV host (IOMMUv2).
+        * IOMMU is also present in a KVM/QEMU VM (IOMMUv1) but is not
+        * currently supported by DPDK. Test for our current environment
+        * and report VA support as appropriate.
+        */
+
+       char *line = NULL;
+       size_t len = 0;
+       char filename[PATH_MAX] = "/proc/cpuinfo";
+       FILE *fp = fopen(filename, "r");
+       bool ret = false;
+
+       if (fp == NULL) {
+               RTE_LOG(ERR, EAL, "%s(): can't open %s: %s\n",
+                       __func__, filename, strerror(errno));
+               return ret;
+       }
+
+       /* Check for a PowerNV platform */
+       while (getline(&line, &len, fp) != -1) {
+               if (strstr(line, "platform") != NULL)
+                       continue;
+
+               if (strstr(line, "PowerNV") != NULL) {
+                       RTE_LOG(DEBUG, EAL, "Running on a PowerNV system\n");
+                       ret = true;
+                       break;
+               }
+       }
+
+       free(line);
+       fclose(fp);
+       return ret;
 }
 #else
 bool