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>,
David Woodhouse <dwmw2@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
Nirmal Patel <nirmal.patel@intel.com>,
Kapil Karkra <kapil.karkra@intel.com>,
Will Deacon <will@kernel.org>,
Jon Derrick <jonathan.derrick@intel.com>
Subject: [PATCH v2 0/2] VMD MSI Remapping Bypass
Date: Thu, 4 Feb 2021 12:09:04 -0700 [thread overview]
Message-ID: <20210204190906.38515-1-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.
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
next 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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