[PATCH v2] pci: read amd iommu virtual address width

[Michael Piszczek <mpiszczek@ddn.com>]

Add code to read the virtual address width for AMD processors.

Signed-off-by: Michael Piszczek <mpiszczek@ddn.com>
---
 drivers/bus/pci/linux/pci.c | 43 +++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index e521459870..0c6d79ca74 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -4,6 +4,7 @@
 
 #include <string.h>
 #include <dirent.h>
+#include <sys/stat.h>
 
 #include <rte_log.h>
 #include <rte_bus.h>
@@ -492,6 +493,38 @@ rte_pci_scan(void)
 }
 
 #if defined(RTE_ARCH_X86)
+
+static uint64_t
+pci_device_amd_iommu_support_va(const struct rte_pci_addr *addr)
+{
+#define RD_AMD_CAP_VASIZE_SHIFT 15
+#define RD_AMD_CAP_VASIZE_MASK (0x7F << RD_AMD_CAP_VASIZE_SHIFT)
+
+	char filename[PATH_MAX];
+	FILE *fp;
+	uint64_t amd_cap_reg = 0;
+
+	snprintf(filename, sizeof(filename),
+		"%s/" PCI_PRI_FMT "/iommu/amd-iommu/cap",
+		rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
+		addr->function);
+
+	fp = fopen(filename, "r");
+	if (fp == NULL)
+		return 0;
+
+	/* We have an Amd IOMMU */
+	if (fscanf(fp, "%" PRIx64, &amd_cap_reg) != 1) {
+		RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);
+		fclose(fp);
+		return 0;
+	}
+
+	fclose(fp);
+
+	return ((amd_cap_reg & RD_AMD_CAP_VASIZE_MASK) >> RD_AMD_CAP_VASIZE_SHIFT) + 1;
+}
+
 bool
 pci_device_iommu_support_va(const struct rte_pci_device *dev)
 {
@@ -501,6 +534,16 @@ pci_device_iommu_support_va(const struct rte_pci_device *dev)
 	char filename[PATH_MAX];
 	FILE *fp;
 	uint64_t mgaw, vtd_cap_reg = 0;
+	struct stat s;
+
+	if (stat("/sys/class/iommu/ivhd2/amd-iommu", &s) == 0) {
+		mgaw = pci_device_amd_iommu_support_va(addr);
+		if (mgaw > 0) {
+			rte_mem_set_dma_mask(mgaw);
+			return true;
+		}
+		return false;
+	}
 
 	snprintf(filename, sizeof(filename),
 		 "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
-- 
2.34.1