From: Leon Romanovsky <leon@kernel.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: 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>,
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, 16 Feb 2023 09:26:15 +0200 [thread overview]
Message-ID: <Y+3al/a3HPrvfNgh@unreal> (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.
> > > Also, it states that the Smallest Translation Unit (STU) for VFs must be
> > > hardwired to Zero and the associated PF's value applies to VFs STU.
> > >
> > > The current code allows to enable ATS on VFs only if it is already
> > > enabled on associated PF, which is not necessary as per the specification.
> > >
> > > It is only required to have valid STU programmed on PF to enable
> > > ATS on VFs. Adding code to write the first VFs STU to a PF's STU
> > > when PFs ATS is not enabled.
> >
> > Can you please add here quotes from the spec and its version? I don't see
> > anything like this in my version of PCIe specification.
>
> See PCIe r6.0, sec 10.5.1.
Awesome, I have old versions.
Thanks
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next prev parent reply other threads:[~2023-02-16 7:27 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 [this message]
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
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