Re: [dpdk-dev] [PATCH v2] vfio: Fix overflow while assigning vfio BAR region offset and size

[Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>]

Hi Alejandro,

On Mon, Jul 06, 2015 at 16:45:01 +0100, Alejandro Lucero wrote:
> Hi all,
> 
> From the kernel VFIO maintainer:
> 
> "I suppose in the short term, mmap should not be advertised as available
> on 32bit hosts.  Thanks,"
> 
> So, as VFIO support for 32bit systems is broken, DPDK should not configure
> VFIO in that case.
> 

Thank you very much for the clarification.

> 
> If we need to support 4G BARs, our only choice is really to extend the
> vfio region support for a separate file descriptor per region.  The only
> devices I'm aware of with 4G BARs are Nvidia Tesla.  This is possible,
> but I would expect such devices would be extremely rare on 32bit hosts.
> 

Our Chelsio T5 cards can also have 4G bar size. So, it seems this won't work
on 32-bit with current state of kernel vfio driver.

Nevertheless, updating your patch with below diff works fine on 64-bit
for vfio testing on Chelsio T5 cards and it compiles for 32-bit targets
as well.


diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
index 426953a..6127f5f 100644
--- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
@@ -728,7 +728,7 @@ pci_vfio_map_resource(struct rte_pci_device *dev)
                struct vfio_region_info reg = { .argsz = sizeof(reg) };
                void *bar_addr;
                struct memreg {
-                       uint32_t offset, size;
+                       unsigned long offset, size;
                } memreg[2] = {};

                reg.index = i;
@@ -771,7 +771,7 @@ pci_vfio_map_resource(struct rte_pci_device *dev)
                                RTE_LOG(DEBUG, EAL,
                                        "Trying to map BAR %d that contains the MSI-X "
                                        "table. Trying offsets: "
-                                       "%04x:%04x, %04x:%04x\n", i,
+                                       "0x%04lx:0x%04lx, 0x%04lx:0x%04lx\n", i,
                                        memreg[0].offset, memreg[0].size,
                                        memreg[1].offset, memreg[1].size);
                        }


Thanks,
Rahul