[dpdk-dev] [PATCH] bus/pci: Add VA support for PowerVM system LPARs

[David Christensen]

Add IOMMU detection logic for PowerVM LPARs.

PowerNV $ cat /proc/cpuinfo
...
timebase     : 512000000
platform     : PowerNV
model        : 8335-GTW

PowerVM LPAR $ cat /proc/cpuinfo
...
timebase     : 512000000
platform     : pSeries
model        : IBM,9009-22A
machine      : CHRP IBM,9009-22A
MMU          : Hash

PowerNV KVM Guest $ cat /proc/cpuinfo
...
timebase     : 512000000
platform     : pSeries
model        : IBM pSeries (emulated by qemu)
machine      : CHRP IBM pSeries (emulated by qemu)
MMU          : Radix

Signed-off-by: David Christensen <drc at linux.vnet.ibm.com>
Reviewed-by: Thinh Tran <thinhtr at linux.vnet.ibm.com>
---
 drivers/bus/pci/linux/pci.c | 41 ++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index 0dc99e9cb2..4a0904a53a 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -549,16 +549,22 @@ bool
 pci_device_iommu_support_va(__rte_unused const struct rte_pci_device *dev)
 {
 	/*
-	 * 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.
+	 * All POWER systems support an IOMMU, but only IOMMUv2 supports
+	 * IOVA = VA in DPDK. Check contents of /proc/cpuinfo to find the
+	 * system.
+	 *
+	 * Platform | Model |  IOMMU  | VA? |             Comment
+	 * ---------+-------+---------+-----+---------------------------------
+	 *  PowerNV |  N/A  | IOMMUv2 | Yes | OpenPOWER (Bare Metal)
+	 *  pSeries | ~qemu | IOMMUv2 | Yes | PowerVM Logical Partition (LPAR)
+	 *  pSeries |  qemu | IOMMUv1 |  No | QEMU Virtual Machine
 	 */
 
 	char *line = NULL;
 	size_t len = 0;
 	char filename[PATH_MAX] = "/proc/cpuinfo";
 	FILE *fp = fopen(filename, "r");
+	bool pseries = false, powernv = false, qemu = false;
 	bool ret = false;
 
 	if (fp == NULL) {
@@ -567,20 +573,31 @@ pci_device_iommu_support_va(__rte_unused const struct rte_pci_device *dev)
 		return ret;
 	}
 
-	/* Check for a PowerNV platform */
+	/* Check the "platform" and "model" fields */
 	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;
+		if (strstr(line, "platform") != NULL) {
+			if (strstr(line, "PowerNV") != NULL) {
+				RTE_LOG(DEBUG, EAL, "Running on a PowerNV "
+						"platform\n");
+				powernv = true;
+			} else if (strstr(line, "pSeries") != NULL) {
+				RTE_LOG(DEBUG, EAL, "Running on a pSeries "
+						"platform\n");
+				pseries = true;
+			}
+		} else if (strstr(line, "model") != NULL) {
+			if (strstr(line, "qemu") != NULL) {
+				RTE_LOG(DEBUG, EAL, "Found qemu emulation\n");
+				qemu = true;
+			}
 		}
 	}
 
 	free(line);
 	fclose(fp);
+
+	if (powernv || (pseries && !qemu))
+		ret = true;
 	return ret;
 }
 #else
-- 
2.27.0