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* [PATCH v2 0/2] VMD MSI Remapping Bypass
@ 2021-02-04 19:09 Jon Derrick
  2021-02-04 19:09 ` [PATCH v2 1/2] iommu/vt-d: Use Real PCI DMA device for IRTE Jon Derrick
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Jon Derrick @ 2021-02-04 19:09 UTC (permalink / raw)
  To: linux-pci, iommu
  Cc: Bjorn Helgaas, Lorenzo Pieralisi, David Woodhouse, Lu Baolu,
	Joerg Roedel, Nirmal Patel, Kapil Karkra, Will Deacon,
	Jon Derrick

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.

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

-- 
2.27.0


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-02-06  3:25 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-02-04 19:09 [PATCH v2 0/2] VMD MSI Remapping Bypass Jon Derrick
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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