From: Alexander Duyck <alexander.duyck@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
iommu@lists.linux.dev
Subject: Re: Question about reserved_regions w/ Intel IOMMU
Date: Wed, 7 Jun 2023 16:03:54 -0700 [thread overview]
Message-ID: <CAKgT0UfMeVOz6AOqSvVvzpsedGDiXCNQrjM+4KDv7qJJ1orpsw@mail.gmail.com> (raw)
In-Reply-To: <CAKgT0UezciLjHacOx372+v8MZkDf22D5Thn82n-07xxKy_0FTQ@mail.gmail.com>
On Wed, Jun 7, 2023 at 3:40 PM Alexander Duyck
<alexander.duyck@gmail.com> wrote:
>
> I am running into a DMA issue that appears to be a conflict between
> ACS and IOMMU. As per the documentation I can find, the IOMMU is
> supposed to create reserved regions for MSI and the memory window
> behind the root port. However looking at reserved_regions I am not
> seeing that. I only see the reservation for the MSI.
>
> So for example with an enabled NIC and iommu enabled w/o passthru I am seeing:
> # cat /sys/bus/pci/devices/0000\:83\:00.0/iommu_group/reserved_regions
> 0x00000000fee00000 0x00000000feefffff msi
>
> Shouldn't there also be a memory window for the region behind the root
> port to prevent any possible peer-to-peer access?
Since the iommu portion of the email bounced I figured I would fix
that and provide some additional info.
I added some instrumentation to the kernel to dump the resources found
in iova_reserve_pci_windows. From what I can tell it is finding the
correct resources for the Memory and Prefetchable regions behind the
root port. It seems to be calling reserve_iova which is successfully
allocating an iova to reserve the region.
However still no luck on why it isn't showing up in reserved_regions.
next prev parent reply other threads:[~2023-06-07 23:04 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-07 22:40 Question about reserved_regions w/ Intel IOMMU Alexander Duyck
2023-06-07 23:03 ` Alexander Duyck [this message]
2023-06-08 3:03 ` Baolu Lu
2023-06-08 14:33 ` Alexander Duyck
2023-06-08 15:38 ` Ashok Raj
2023-06-08 17:10 ` Alexander Duyck
2023-06-08 17:52 ` Ashok Raj
2023-06-08 18:15 ` Alexander Duyck
2023-06-08 18:02 ` Robin Murphy
2023-06-08 18:17 ` Alexander Duyck
2023-06-08 15:28 ` Robin Murphy
2023-06-13 15:54 ` Jason Gunthorpe
2023-06-16 8:39 ` Tian, Kevin
2023-06-16 12:20 ` Jason Gunthorpe
2023-06-16 15:27 ` Alexander Duyck
2023-06-16 16:34 ` Robin Murphy
2023-06-16 18:59 ` Jason Gunthorpe
2023-06-19 10:20 ` Robin Murphy
2023-06-19 14:02 ` Jason Gunthorpe
2023-06-20 14:57 ` Alexander Duyck
2023-06-20 16:55 ` Jason Gunthorpe
2023-06-20 17:47 ` Alexander Duyck
2023-06-21 11:30 ` Robin Murphy
2023-06-16 18:48 ` Jason Gunthorpe
2023-06-21 8:16 ` Tian, Kevin
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