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From: Jon Derrick <>
To: <>, <>
Cc: Bjorn Helgaas <>,
	Lorenzo Pieralisi <>,
	David Woodhouse <>,
	Lu Baolu <>,
	Joerg Roedel <>,
	Nirmal Patel <>,
	Kapil Karkra <>,
	Will Deacon <>,
	Jon Derrick <>
Subject: [PATCH v2 0/2] VMD MSI Remapping Bypass
Date: Thu,  4 Feb 2021 12:09:04 -0700	[thread overview]
Message-ID: <> (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.

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:
V1, 6/6:

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        | 60 +++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 13 deletions(-)


             reply	other threads:[~2021-02-04 19:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 19:09 Jon Derrick [this message]
2021-02-04 19:09 ` [PATCH v2 1/2] iommu/vt-d: Use Real PCI DMA device for IRTE Jon Derrick
2021-02-05  1:39   ` Lu Baolu
2021-02-04 19:09 ` [PATCH v2 2/2] PCI: vmd: Disable MSI/X remapping when possible Jon Derrick
2021-02-05 21:57   ` Bjorn Helgaas
2021-02-06  2:50     ` Derrick, Jonathan
2021-02-05  8:45 ` [PATCH v2 0/2] VMD MSI Remapping Bypass Joerg Roedel

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