[PATCH v3 0/2] VMD MSI Remapping Bypass

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>,
	Jon Derrick <jonathan.derrick@intel.com>
Subject: [PATCH v3 0/2] VMD MSI Remapping Bypass
Date: Fri,  5 Feb 2021 20:35:00 -0700	[thread overview]
Message-ID: <20210206033502.103964-1-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.

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        | 61 +++++++++++++++++++++++------
 2 files changed, 51 insertions(+), 13 deletions(-)

-- 
2.27.0