From 781bb36add9e43907a16a1303a13808ae53cfa31 Mon Sep 17 00:00:00 2001

From: Maxime Coquelin <maxime.coquelin@redhat.com>

Date: Fri, 12 Jan 2018 11:22:20 +0100

Subject: [PATCH] bus/pci: forbid IOVA mode if IOMMU address width too small

[ upstream commit 54a328f552ff2e0098c3f96f9e32302675f2bcf4 ]

Intel VT-d supports different address widths for the IOVAs, from

39 bits to 56 bits.

While recent processors support at least 48 bits, VT-d emulation

currently only supports 39 bits. It makes DMA mapping to fail in this

case when using VA as IOVA mode, as user-space virtual addresses uses

up to 47 bits (see kernel's Documentation/x86/x86_64/mm.txt).

This patch parses VT-d CAP register value available in sysfs, and

forbid VA as IOVA mode if the GAW is 39 bits or unknown.

Fixes: f37dfab21c98 ("drivers/net: enable IOVA mode for Intel PMDs")

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Tested-by: Chas Williams <chas3@att.com>

---

 drivers/bus/pci/linux/pci.c | 90 ++++++++++++++++++++++++++++++++++++++++-----

 1 file changed, 81 insertions(+), 9 deletions(-)

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c

index ec31216..74deef3 100644

--- a/drivers/bus/pci/linux/pci.c

+++ b/drivers/bus/pci/linux/pci.c

@@ -577,4 +577,80 @@

 }

+#if defined(RTE_ARCH_X86)

+static bool

+pci_one_device_iommu_support_va(struct rte_pci_device *dev)

+{

+#define VTD_CAP_MGAW_SHIFT	16

+#define VTD_CAP_MGAW_MASK	(0x3fULL << VTD_CAP_MGAW_SHIFT)

+#define X86_VA_WIDTH 47 /* From Documentation/x86/x86_64/mm.txt */

+	struct rte_pci_addr *addr = &dev->addr;

+	char filename[PATH_MAX];

+	FILE *fp;

+	uint64_t mgaw, vtd_cap_reg = 0;

+

+	snprintf(filename, sizeof(filename),

+		 "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",

+		 rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,

+		 addr->function);

+	if (access(filename, F_OK) == -1) {

+		/* We don't have an Intel IOMMU, assume VA supported*/

+		return true;

+	}

+

+	/* We have an intel IOMMU */

+	fp = fopen(filename, "r");

+	if (fp == NULL) {

+		RTE_LOG(ERR, EAL, "%s(): can't open %s\n", __func__, filename);

+		return false;

+	}

+

+	if (fscanf(fp, "%" PRIx64, &vtd_cap_reg) != 1) {

+		RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);

+		fclose(fp);

+		return false;

+	}

+

+	fclose(fp);

+

+	mgaw = ((vtd_cap_reg & VTD_CAP_MGAW_MASK) >> VTD_CAP_MGAW_SHIFT) + 1;

+	if (mgaw < X86_VA_WIDTH)

+		return false;

+

+	return true;

+}

+#elif defined(RTE_ARCH_PPC_64)

+static bool

+pci_one_device_iommu_support_va(__rte_unused struct rte_pci_device *dev)

+{

+	return false;

+}

+#else

+static bool

+pci_one_device_iommu_support_va(__rte_unused struct rte_pci_device *dev)

+{

+	return true;

+}

+#endif

+

+/*

+ * All devices IOMMUs support VA as IOVA

+ */

+static bool

+pci_devices_iommu_support_va(void)

+{

+	struct rte_pci_device *dev = NULL;

+	struct rte_pci_driver *drv = NULL;

+

+	FOREACH_DRIVER_ON_PCIBUS(drv) {

+		FOREACH_DEVICE_ON_PCIBUS(dev) {

+			if (!rte_pci_match(drv, dev))

+				continue;

+			if (!pci_one_device_iommu_support_va(dev))

+				return false;

+		}

+	}

+	return true;

+}

+

 /*

  * Get iommu class of PCI devices on the bus.

@@ -587,10 +663,5 @@ enum rte_iova_mode

 	bool has_iova_va;

 	bool is_bound_uio;

-	bool spapr_iommu =

-#if defined(RTE_ARCH_PPC_64)

-		true;

-#else

-		false;

-#endif

+	bool iommu_no_va;

 	is_bound = pci_one_device_is_bound();

@@ -600,4 +671,5 @@ enum rte_iova_mode

 	has_iova_va = pci_one_device_has_iova_va();

 	is_bound_uio = pci_one_device_bound_uio();

+	iommu_no_va = !pci_devices_iommu_support_va();

 #ifdef VFIO_PRESENT

 	is_vfio_noiommu_enabled = rte_vfio_noiommu_is_enabled() == true ?

@@ -606,5 +678,5 @@ enum rte_iova_mode

 	if (has_iova_va && !is_bound_uio && !is_vfio_noiommu_enabled &&

-			!spapr_iommu)

+			!iommu_no_va)

 		return RTE_IOVA_VA;

@@ -615,6 +687,6 @@ enum rte_iova_mode

 		if (is_bound_uio)

 			RTE_LOG(WARNING, EAL, "few device bound to UIO\n");

-		if (spapr_iommu)

-			RTE_LOG(WARNING, EAL, "sPAPR IOMMU does not support IOVA as VA\n");

+		if (iommu_no_va)

+			RTE_LOG(WARNING, EAL, "IOMMU does not support IOVA as VA\n");

 	}

-- 

1.8.3.1