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Message-ID: <20241030205703.GA1219329@bhelgaas>
Date: Wed, 30 Oct 2024 15:57:03 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Jan Kiszka <jan.kiszka@...mens.com>
Cc: Nishanth Menon <nm@...com>, Santosh Shilimkar <ssantosh@...nel.org>,
Vignesh Raghavendra <vigneshr@...com>,
Tero Kristo <kristo@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-pci@...r.kernel.org, Siddharth Vadapalli <s-vadapalli@...com>,
Bao Cheng Su <baocheng.su@...mens.com>,
Hua Qian Li <huaqian.li@...mens.com>,
Diogo Ivo <diogo.ivo@...mens.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Krzysztof Wilczyński <kw@...ux.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>
Subject: Re: [PATCH v6 0/7] soc: ti: Add and use PVU on K3-AM65 for DMA
isolation
On Mon, Sep 09, 2024 at 07:03:53PM +0200, Jan Kiszka wrote:
> Changes in v6:
> - make restricted DMA memory-region available to all pci-keystone
> devices, moving property to unconditional section (patch 2)
>
> Changes in v5:
> - resolve review comments on pci-host bindings
> - reduce DMA memory regions to 1 - swiotlb does not support more
> - move activation into overlay (controlled via firmware)
> - use ks_init_vmap helper instead of loop in
> rework ks_init_restricted_dma
> - add more comments to pci-keystone
> - use 2 chained TLBs of PVU to support maximum of swiotlb (320 MB)
>
> Changes in v4:
> - reorder patch queue, moving all DTS changes to the back
> - limit activation to IOT2050 Advanced variants
> - move DMA pool to allow firmware-based expansion it up to 512M
>
> Changes in v3:
> - fix ti,am654-pvu.yaml according to review comments
> - address review comments on ti,am65-pci-host.yaml
> - differentiate between different compatibles in ti,am65-pci-host.yaml
> - move pvu nodes to k3-am65-main.dtsi
> - reorder patch series, pulling bindings and generic DT bits to the front
>
> Changes in v2:
> - fix dt_bindings_check issues (patch 1)
> - address first review comments (patch 2)
> - extend ti,am65-pci-host bindings for PVU (new patch 3)
>
> Only few of the K3 SoCs have an IOMMU and, thus, can isolate the system
> against DMA-based attacks of external PCI devices. The AM65 is without
> an IOMMU, but it comes with something close to it: the Peripheral
> Virtualization Unit (PVU).
>
> The PVU was originally designed to establish static compartments via a
> hypervisor, isolate those DMA-wise against each other and the host and
> even allow remapping of guest-physical addresses. But it only provides
> a static translation region, not page-granular mappings. Thus, it cannot
> be handled transparently like an IOMMU.
>
> Now, to use the PVU for the purpose of isolated PCI devices from the
> Linux host, this series takes a different approach. It defines a
> restricted-dma-pool for the PCI host, using swiotlb to map all DMA
> buffers from a static memory carve-out. And to enforce that the devices
> actually follow this, a special PVU soc driver is introduced. The driver
> permits access to the GIC ITS and otherwise waits for other drivers that
> detect devices with constrained DMA to register pools with the PVU.
>
> For the AM65, the first (and possibly only) driver where this is
> introduced is the pci-keystone host controller. Finally, this series
> provides a DT overlay for the IOT2050 Advanced devices (all have
> MiniPCIe or M.2 extension slots) to make use of this protection scheme.
> Application of this overlay will be handled by firmware.
>
> Due to the cross-cutting nature of these changes, multiple subsystems
> are affected. However, I wanted to present the whole thing in one series
> to allow everyone to review with the complete picture in hands. If
> preferred, I can also split the series up, of course.
I'm not sure where this ended up.
The pci-keystone.c patch looks OK to me, and I don't see any comments
from the PCI folks who normally take care of host controller drivers.
I guess it depends on the soc PVU driver, so I'll ack the keystone
part and whoever takes the soc part can include it.
> CC: Bjorn Helgaas <bhelgaas@...gle.com>
> CC: "Krzysztof Wilczyński" <kw@...ux.com>
> CC: linux-pci@...r.kernel.org
> CC: Lorenzo Pieralisi <lpieralisi@...nel.org>
>
> Jan Kiszka (7):
> dt-bindings: soc: ti: Add AM65 peripheral virtualization unit
> dt-bindings: PCI: ti,am65: Extend for use with PVU
> soc: ti: Add IOMMU-like PVU driver
> PCI: keystone: Add support for PVU-based DMA isolation on AM654
> arm64: dts: ti: k3-am65-main: Add PVU nodes
> arm64: dts: ti: k3-am65-main: Add VMAP registers to PCI root complexes
> arm64: dts: ti: iot2050: Add overlay for DMA isolation for devices
> behind PCI RC
>
> .../bindings/pci/ti,am65-pci-host.yaml | 28 +-
> .../bindings/soc/ti/ti,am654-pvu.yaml | 51 ++
> arch/arm64/boot/dts/ti/Makefile | 5 +
> arch/arm64/boot/dts/ti/k3-am65-main.dtsi | 38 +-
> ...am6548-iot2050-advanced-dma-isolation.dtso | 33 ++
> drivers/pci/controller/dwc/pci-keystone.c | 108 ++++
> drivers/soc/ti/Kconfig | 4 +
> drivers/soc/ti/Makefile | 1 +
> drivers/soc/ti/ti-pvu.c | 500 ++++++++++++++++++
> include/linux/ti-pvu.h | 16 +
> 10 files changed, 777 insertions(+), 7 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/soc/ti/ti,am654-pvu.yaml
> create mode 100644 arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced-dma-isolation.dtso
> create mode 100644 drivers/soc/ti/ti-pvu.c
> create mode 100644 include/linux/ti-pvu.h
>
> --
> 2.43.0
>
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