SMMU, Unhandled context fault

[Peng Fan <van.freenix@gmail.com>]

Hi Julien, Stefano

I met an issue when passthrough a device to DomU, and have no clear idea what's wrong.
"
(XEN) smmu: /iommu@5c800000: Unhandled context fault: iova=0x42188000, fsynr=0x433, cb=0
(XEN) smmu: /iommu@5c800000: Unhandled context fault: iova=0x42188020, fsynr=0x433, cb=0
"
fsynr is 0x433, PTWF is 1, which means
"An external fault occurred while processing a translation table walk"

My DomU cfg is:
"
kernel = "/root/xen/Image"
device_tree = "/root/xen/sdhc.dtb"
dtdev = [ "/usdhc@5a240000" ]
iomem = [ "0x5a240,0x10@0x1a240"]
irqs = [ 257 ]
memory = "128"
name = "domU-sdhc-test"
vcpus = 1
serial="pty"
disk = [ 'phy:/dev/loop0,xvda,w' ]
extra = "console=hvc0 root=/dev/xvda debug=/bin/sh"
"

I saw this patch: http://www.gossamer-threads.com/lists/xen/devel/428030
"xen/arm: Force broadcast of TLB and instruction cache maintenance instructions"
So I guess should we have a similar fix for SMMU TLB?
From my failure log, It should be that TCU can not find the machine address for iova(guest physical address).
I remember that When create domU for ARM, the memory is allocated from heap, so machine pages
should be there allocated. Also SMMU share the mmu table with domU mmu table.
I guess there maybe something wrong with SMMU TLB related handling. But I have no
clear idea on this. Please advise.

Thanks in advance,
Peng.

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