linux-kernel - Re: [PATCH v2 00/33] iommu: Move iommu_group setup to IOMMU core code

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Message-ID: <20200602000236.j4m3jvluzdhjngdc@cantor>
Date:   Mon, 1 Jun 2020 17:02:36 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Clark <robdclark@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        linux-s390@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-rockchip@...ts.infradead.org,
        iommu@...ts.linux-foundation.org,
        linux-mediatek@...ts.infradead.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v2 00/33] iommu: Move iommu_group setup to IOMMU core code

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
>_______________________________________________
>iommu mailing list
>iommu@...ts.linux-foundation.org
>https://lists.linuxfoundation.org/mailman/listinfo/iommu

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