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From: Jason Gunthorpe <jgg@nvidia.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Vidya Sagar <vidyas@nvidia.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	Gal Shalom <galshalom@nvidia.com>,
	Leon Romanovsky <leonro@nvidia.com>,
	Thierry Reding <treding@nvidia.com>,
	Jon Hunter <jonathanh@nvidia.com>,
	Masoud Moshref Javadi <mmoshrefjava@nvidia.com>,
	Shahaf Shuler <shahafs@nvidia.com>,
	Vikram Sethi <vsethi@nvidia.com>,
	Shanker Donthineni <sdonthineni@nvidia.com>,
	Jiandi An <jan@nvidia.com>, Tushar Dave <tdave@nvidia.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Krishna Thota <kthota@nvidia.com>,
	Manikanta Maddireddy <mmaddireddy@nvidia.com>,
	"sagar.tv@gmail.com" <sagar.tv@gmail.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>
Subject: Re: [PATCH V3] PCI: Extend ACS configurability
Date: Mon, 10 Jun 2024 08:38:49 -0300	[thread overview]
Message-ID: <20240610113849.GO19897@nvidia.com> (raw)
In-Reply-To: <20240607193055.GA855605@bhelgaas>

On Fri, Jun 07, 2024 at 02:30:55PM -0500, Bjorn Helgaas wrote:
> "Correctly" is not quite the right word here; it's just a fact that
> the ACS settings determined at boot time result in certain IOMMU
> groups.  If the user desires different groups, it's not that something
> is "incorrect"; it's just that the user may have to accept less
> isolation to get the desired IOMMU groups.

That is not quite accurate.. There are HW configurations where ACS
needs to be a certain way for the HW to work with P2P at all. It isn't
just an optimization or the user accepts something, if they want P2P
at all they must get a ACS configuration appropriate for their system.

Jason

  reply	other threads:[~2024-06-10 11:38 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-21 11:09 [PATCH V2] PCI: Extend ACS configurability Vidya Sagar
2024-05-21 15:44 ` kernel test robot
2024-05-23  6:35 ` [PATCH V3] " Vidya Sagar
2024-05-23 14:59   ` Bjorn Helgaas
2024-05-23 15:16     ` Jason Gunthorpe
2024-06-03  7:50       ` Vidya Sagar
2024-06-07 19:30         ` Bjorn Helgaas
2024-06-10 11:38           ` Jason Gunthorpe [this message]
2024-06-12 21:29             ` Bjorn Helgaas
2024-06-12 23:23               ` Jason Gunthorpe
2024-06-13 22:05                 ` Bjorn Helgaas
2024-06-13 23:36                   ` Jason Gunthorpe
2024-06-13 22:38                 ` Alex Williamson
2024-06-12 12:19   ` Jason Gunthorpe
2024-06-25 15:31   ` [PATCH V4] " Vidya Sagar
2024-06-25 16:26     ` Lukas Wunner
2024-06-25 16:39       ` Jason Gunthorpe
2024-06-26  6:02       ` Leon Romanovsky
2024-06-26  7:40     ` Tian, Kevin
2024-06-26 11:50       ` Jason Gunthorpe
2024-07-08 14:39     ` Jason Gunthorpe
2024-07-12 21:57     ` Bjorn Helgaas
2024-09-25  5:06     ` Jiri Slaby
2024-09-25  5:29       ` Jiri Slaby
2024-09-25  5:49         ` Jiri Slaby
2024-10-01 19:33           ` Jason Gunthorpe
2024-10-07 16:36             ` Steffen Dirkwinkel
2024-10-07 20:43       ` Bjorn Helgaas

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