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Date:   Mon, 1 Jun 2020 17:02:36 -0700
From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        David Woodhouse <dwmw2@infradead.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Clark <robdclark@gmail.com>,
        Heiko Stuebner <heiko@sntech.de>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
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Subject: Re: [PATCH v2 00/33] iommu: Move iommu_group setup to IOMMU core code
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Reply-To: Jerry Snitselaar <jsnitsel@redhat.com>
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        Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
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        Marek Szyprowski <m.szyprowski@samsung.com>,
        Kukjin Kim <kgene@kernel.org>,
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        Bjorn Andersson <bjorn.andersson@linaro.org>,
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        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
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 <20200529221623.qc6twmpzryh7nkvb@cantor>
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On Tue Jun 02 20, Lu Baolu wrote:
>Hi Jerry,
>
>On 6/1/20 6:42 PM, Jerry Snitselaar wrote:
>>>
>>>Hi Joerg,
>>>
>>>With this patchset, I have an epyc system where if I boot with
>>>iommu=nopt and force a dump I will see some io page faults for a nic
>>>on the system. The vmcore is harvested and the system reboots. I
>>>haven't reproduced it on other systems yet, but without the patchset I
>>>don't see the io page faults during the kdump.
>>>
>>>Regards,
>>>Jerry
>>
>>I just hit an issue on a separate intel based system (kdump iommu=nopt),
>>where it panics in during intel_iommu_attach_device, in is_aux_domain,
>>due to device_domain_info being DEFER_DEVICE_DOMAIN_INFO. That doesn't
>>get set to a valid address until the domain_add_dev_info call.
>>
>>Is it as simple as the following?
>
>I guess you won't hit this issue if you use iommu/next branch of Joerg's
>tree. We've changed to use a generic helper to retrieve the valid per
>device iommu data or NULL (if there's no).
>
>Best regards,
>baolu
>

Yeah, that will solve the panic. 

>>
>>diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>>index 29d3940847d3..f1bbeed46a4c 100644
>>--- a/drivers/iommu/intel-iommu.c
>>+++ b/drivers/iommu/intel-iommu.c
>>@@ -5053,8 +5053,8 @@ is_aux_domain(struct device *dev, struct 
>>iommu_domain *domain)
>>  {
>>         struct device_domain_info *info = dev->archdata.iommu;
>>
>>-       return info && info->auxd_enabled &&
>>-                       domain->type == IOMMU_DOMAIN_UNMANAGED;
>>+       return info && info != DEFER_DEVICE_DOMAIN_INFO &&
>>+               info->auxd_enabled && domain->type == 
>>IOMMU_DOMAIN_UNMANAGED;
>>  }
>>
>>  static void auxiliary_link_device(struct dmar_domain *domain,
>>
>>
>>Regards,
>>Jerry
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