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From: Joerg Roedel <joro@8bytes.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, jean-philippe@linaro.org,
	darren@os.amperecomputing.com, scott@os.amperecomputing.com,
	Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	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, 16 Feb 2023 11:23:29 +0100	[thread overview]
Message-ID: <Y+4EITP08CKPWMWl@8bytes.org> (raw)
In-Reply-To: <20230215205726.GA3213227@bhelgaas>

On Wed, Feb 15, 2023 at 02:57:26PM -0600, Bjorn Helgaas wrote:
> [+cc Will, Robin, Joerg for arm-smmu-v3 page size question]
> 
> On Sun, Feb 12, 2023 at 08:14:48PM +0200, Leon Romanovsky wrote:
> > On Wed, Feb 08, 2023 at 10:43:21AM -0800, Ganapatrao Kulkarni wrote:
> > > As per PCIe specification(section 10.5), If a VF implements an
> > > ATS capability, its associated PF must implement an ATS capability.
> > > The ATS Capabilities in VFs and their associated PFs are permitted to
> > > be enabled independently.

Well, the spec is one thing, existing hardware the other. Have you
checked the history of the PF-before-VF requirement before making that
change?

It is possible that early PASID-capable hardware actually required
PF-before-VF enablement of ATS.

Regards,

	Joerg

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  parent reply	other threads:[~2023-02-16 10:24 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 [this message]
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

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