[Xen-users] DMA Crash when I test GPL Windows PV Driver by iperf

[Qian Huibin <qianhb@xxxxxxxxx>]

Hey All,

 

When I did a test of GPL Windows PV Driver on Windows XP SP2 by iperf, I found a DMA Crash.

And the Crash occurs every times.

The test is as following:

I install GPL Windows PV Driver (0.10.0.130) for XP as DomU , and Suse 11 as Dom0 on Xen 3.3.1.

When I set DomU as iperf's Client and Dom0 as Server.

 

iperf client on DomU (XP):

iperf -c $SERVER_IP -i 1 -l 1 -w 64k

iperf server on Dom0 (Suse 11 & xen 3.3.1)

iperf -s -l 1 l -w 64k

 

Scatter/gather enabled

 

IF I SET -l (buff size ) as 1 byte ( in fact from 1 byte to 9 bytes), the DomU (XP) crashed everything (Scatter/gather enabled).

 

I use windbg to analyze the Windows Mem Dump, I found the crash callstack  as following:

 

XenNet_RxBufferCheck() -> ... ->  XenPci_DOP_BuildScatterGatherList() -> XenPci_DOP_BuildScatterGatherListButDontExecute()

 

        for (i = 0; remaining > 0; i++)
        {
          pfn = MmGetMdlPfnArray(curr_mdl)[pfn_offset + i];
          ASSERT(pfn);
          gref = (grant_ref_t)GntTbl_GrantAccess(xpdd, 0, (ULONG)pfn, FALSE, INVALID_GRANT_REF);
          ASSERT(gref != INVALID_GRANT_REF); // gref gets a value of INVALID_GRANT_REF, Crash occurs!!!
          sglist->Elements[sg_element].Address.QuadPart = (LONGLONG)(gref << PAGE_SHIFT) | offset;
          sglist->Elements[sg_element].Length = min(min(PAGE_SIZE - offset, remaining), total_remaining);
          total_remaining -= sglist->Elements[sg_element].Length;
          remaining -= sglist->Elements[sg_element].Length;
          offset = 0;
          sg_element++;
        }

I donot know how to fix it.

I think the Satter/Gather is related to transfer NOT receive, why crash when receving data.

because of  -l set as 1 byte, then using more gref to store outgoing data, and gref is NOT enough?

 

pls have a look at this problem.

 

Thanks

--
Huibin.QIAN
Hangzhou,China

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