[PATCH v2 4/6] bus/pci: use IOVAs dmak mask check when setting IOVA mode

[Alejandro Lucero <alejandro.lucero@netronome.com>]

Currently the code precludes IOVA mode if IOMMU hardware reports
less addressing bits than necessary for full virtual memory range.

Although VT-d emulation currently only supports 39 bits, it could
be iovas for allocated memlory being within that supported range.
This patch allows IOVA mode in such a case adding a call to
rte_eal_check_dma_mask using the reported addressing bits by the
IOMMU hardware.

Indeed, memory initialization code has been modified for using lower
virtual addresses than those used by the kernel for 64 bits processes
by default, and therefore memsegs iovas can use 39 bits or less for
most systems. And this is likely 100% true for VMs.

Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
---
 drivers/bus/pci/linux/pci.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index a871549..5cf78d7 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -588,10 +588,8 @@
 	fclose(fp);
 
 	mgaw = ((vtd_cap_reg & VTD_CAP_MGAW_MASK) >> VTD_CAP_MGAW_SHIFT) + 1;
-	if (mgaw < X86_VA_WIDTH)
-		return false;
 
-	return true;
+	return rte_eal_check_dma_mask(mgaw) == 0 ? true : false;
 }
 #elif defined(RTE_ARCH_PPC_64)
 static bool
-- 
1.9.1