From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Leon Romanovsky <leon@kernel.org>,
Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
bhelgaas@google.com, darren@os.amperecomputing.com,
scott@os.amperecomputing.com, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev
Subject: Re: [PATCH] PCI/ATS: Allow to enable ATS on VFs even if it is not enabled on PF
Date: Thu, 23 Feb 2023 15:45:20 +0000 [thread overview]
Message-ID: <Y/eKEMo1moXt3pPP@myrica> (raw)
In-Reply-To: <20230221154624.GA3701506@bhelgaas>
On Tue, Feb 21, 2023 at 09:46:24AM -0600, Bjorn Helgaas wrote:
> It's weird to me that the SMMU is between PCI and memory, but the
> driver seems to insert itself in the middle after PCI enumeration.
> And maybe even after some PCI device driver binding?
No this shouldn't happen, because device drivers expect DMA to be
operational in their probe() function, so at that point the IOMMU must be
configured. The core and IOMMU subsystems enforce probe dependency between
the SMMU and the PCI device, using links described by ACPI or device tree.
Thanks,
Jean
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prev parent reply other threads:[~2023-02-23 15:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Y+ksmNWJdWNkGAU9@unreal>
2023-02-15 20:57 ` [PATCH] PCI/ATS: Allow to enable ATS on VFs even if it is not enabled on PF Bjorn Helgaas
2023-02-16 7:26 ` Leon Romanovsky
2023-02-16 7:46 ` Leon Romanovsky
2023-02-16 10:47 ` Jean-Philippe Brucker
2023-02-16 10:23 ` Joerg Roedel
2023-02-16 11:12 ` Jean-Philippe Brucker
2023-02-16 11:36 ` Ganapatrao Kulkarni
2023-02-21 9:13 ` Ganapatrao Kulkarni
2023-02-21 15:46 ` Bjorn Helgaas
2023-02-23 15:45 ` Jean-Philippe Brucker [this message]
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