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From: Jon Derrick <jonathan.derrick@intel.com>
To: <linux-pci@vger.kernel.org>, <iommu@lists.linux-foundation.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Joerg Roedel <joro@8bytes.org>,
	Nirmal Patel <nirmal.patel@intel.com>,
	Kapil Karkra <kapil.karkra@intel.com>,
	Krzysztof Wilczynski <kw@linux.com>,
	Jon Derrick <jonathan.derrick@intel.com>
Subject: [PATCH v4 0/2] VMD MSI Remapping Bypass
Date: Wed, 10 Feb 2021 09:13:13 -0700	[thread overview]
Message-ID: <20210210161315.316097-1-jonathan.derrick@intel.com> (raw)

The Intel Volume Management Device acts similar to a PCI-to-PCI bridge in that
it changes downstream devices' requester-ids to its own. As VMD supports PCIe
devices, it has its own MSI-X table and transmits child device MSI-X by
remapping child device MSI-X and handling like a demultiplexer.

Some newer VMD devices (Icelake Server) have an option to bypass the VMD MSI-X
remapping table. This allows for better performance scaling as the child device
MSI-X won't be limited by VMD's MSI-X count and IRQ handler.

V3->V4:
Integrated wording suggestions; no functional changes

V2->V3:
Trivial comment fixes
Added acks

V1->V2:
Updated for 5.12-next
Moved IRQ allocation and remapping enable/disable to a more logical location

V1 patches 1-4 were already merged
V1, 5/6: https://patchwork.kernel.org/project/linux-pci/patch/20200728194945.14126-6-jonathan.derrick@intel.com/
V1, 6/6: https://patchwork.kernel.org/project/linux-pci/patch/20200728194945.14126-7-jonathan.derrick@intel.com/


Jon Derrick (2):
  iommu/vt-d: Use Real PCI DMA device for IRTE
  PCI: vmd: Disable MSI-X remapping when possible

 drivers/iommu/intel/irq_remapping.c |  3 +-
 drivers/pci/controller/vmd.c        | 63 +++++++++++++++++++++++------
 2 files changed, 53 insertions(+), 13 deletions(-)

-- 
2.27.0


             reply	other threads:[~2021-02-10 16:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-10 16:13 Jon Derrick [this message]
2021-02-10 16:13 ` [PATCH v4 1/2] iommu/vt-d: Use Real PCI DMA device for IRTE Jon Derrick
2021-02-10 16:13 ` [PATCH v4 2/2] PCI: vmd: Disable MSI-X remapping when possible Jon Derrick
2021-03-17 19:14 ` [PATCH v4 0/2] VMD MSI Remapping Bypass Derrick, Jonathan
2021-03-18  9:07   ` joro
2021-03-18 12:38     ` Lorenzo Pieralisi
2021-03-22 14:11 ` Lorenzo Pieralisi

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