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Re: [Xen-devel] SMMU, Unhandled context fault

Hi Julien,

On Thu, Apr 28, 2016 at 10:37:54AM +0800, Peng Fan wrote:
>Hi Julien,
>On Wed, Apr 27, 2016 at 10:58:28AM +0100, Julien Grall wrote:
>>Hello Peng,
>>On 27/04/2016 03:02, Peng Fan wrote:
>>>On Tue, Apr 26, 2016 at 04:30:03PM +0200, Edgar E. Iglesias wrote:
>>>>On Tue, Apr 26, 2016 at 09:56:33PM +0800, Peng Fan wrote:
>>>>>You mean the PNU bit(Privileged Not Unprivileged) is 1?
>>>>>I did not met Unhandled context fault each time.
>>>>>Actually during my serveral boot test, I only met two times.
>>>>I meant the NSSTATE and NSATTR bits in FSYNR are set to zero. I get the
>>>>impression that the TrustZone state for the SD controller may be
>>>oh. The NSATTR bit is 0. I did not find NSSTATE in my Issue D SMMU spec.
>>>If without xen, only one linux boots up, sd controller can access memory 
>>>DMA without issue.
>>IIRC, by default Linux baremetal does not protect the devices with the SMMU.
>>I would recommend you to check whether the SMMUs are in-used and configured
>>to generate a fault (disable_bypass = 1).
>Ok. I'll set S2CRn to generate fault in xen smmu driver to see whether SMMUs 
>in-used or not.
>I found a patch for errata of mmu-500,
>Do you know this?
>I suspect the unstable issue on my platform seems related to this errata,
>but i do not have details about this errata.

I do the following change:
        //s2cr = S2CR_TYPE_TRANS | S2CR_PRIVCFG_UNPRIV |
                (smmu_domain->cfg.cbndx << S2CR_CBNDX_SHIFT);

Now XEN SMMU driver reports that:
(XEN) smmu: /iommu@5c800000: Unexpected global fault, this could be serious
(XEN) smmu: /iommu@5c800000:    GFSR 0x00000001, GFSYNR0 0x00000004, GFSYNR1 
0x00000011, GFSYNR2 0x00000000

So I think SMMU is working.


>>Julien Grall

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