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[v2,0/2] VMD MSI Remapping Bypass

Message ID 20210204190906.38515-1-jonathan.derrick@intel.com (mailing list archive)
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Series VMD MSI Remapping Bypass | expand

Message

Jon Derrick Feb. 4, 2021, 7:09 p.m. UTC 
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(-)

Comments

Joerg Roedel Feb. 5, 2021, 8:45 a.m. UTC | #1 
On Thu, Feb 04, 2021 at 12:09:04PM -0700, Jon Derrick wrote:
> 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(-)

This probably goes via Bjorn's tree, so

	Acked-by: Joerg Roedel <jroedel@suse.de>