From: James Dong <xmdong@google.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
Joerg Roedel <joro@8bytes.org>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
Jis Ben <jisben@google.com>, James Dong <xmdong@google.com>
Subject: RE: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
Date: Fri, 22 Feb 2019 07:36:58 +0000 [thread overview]
Message-ID: <20190222073658.66798-1-xmdong@google.com> (raw)
In-Reply-To: <fe6dcb4e-03c4-0bbf-c51f-5964b20593dd@linux.intel.com>
Baolu:
Sorry that my last reply email seems not text format. Resend it now.
Thanks for your comments and your patch. Please find below our responses to
each of your comments:
> What does "I/O operation won't work" exactly mean here? Do you see any
> IOMMU fault message? Or, something doesn't work as expected?
Yes, DMAR fault messages as following came out:
[ 354.939896] DMAR: DMAR:[DMA Read] Request device [03:00.1]fault addr 1fdfe80000
[ 354.939896] DMAR:[fault reason 02] Present bit in context entry is clear
> Do you mind checking this?
>
> index 6ecdcf8fc8c0..f62f30bc1339 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -2632,6 +2632,9 @@ static struct dmar_domain
> *find_or_alloc_domain(struct device *dev, int gaw)
> goto out;
> }
>
> + if (!iommu_should_identity_map(dev, 0))
> + return si_domain;
> +
> /* Allocate and initialize new domain for the device */
> domain = alloc_domain(0);
> if (!domain)
Tried this patch, and the same DMAR fault message came out.
Guess it is because of the iommu code path for hotplug devices. If a hotplug
device is rescanned after removal, iommu_bus_notifier will be called as part
of the notifier chains to handle BUS_NOTIFY_ADD_DEVICE event. Along the code
path, intel_iommu_ops->add_device() created an iommu group for this hotplug
device, but failed to create an iommu domain because of the default domain
type IOMMU_DOMAIN_IDENTITY imposed by current IOMMU command line option got
declined by intel_iommu_ops->domain_alloc().
Since si_domain is type of "struct dmar_domain", which is platform dependent,
it is hard to make this change in intel_iommu_ops->domain_alloc().
In your patch, function find_or_alloc_domain() is not in the code path of
BUS_NOTIFY_ADD_DEVICE event notifier chain.
Please let us know if your have more concerns and suggestions.
Best Regards,
James
next prev parent reply other threads:[~2019-02-22 7:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-22 2:44 [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting James Dong
2019-02-22 5:06 ` Lu Baolu
2019-02-22 5:30 ` Lu Baolu
2019-02-22 7:36 ` James Dong [this message]
2019-02-24 8:51 ` Lu Baolu
2019-02-24 16:10 ` James Dong
[not found] ` <CADcZez2q7aUL=ahHSGnfO2QDjKL052AePd=TsxkCK-O7EcW77Q@mail.gmail.com>
2019-02-22 7:42 ` Lu Baolu
2019-02-22 8:28 ` James Dong
2019-02-22 18:10 ` Jis Ben
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