Re: [RFC RESEND v5 2/4] hw/misc: Introduce iommu-testdev for bare-metal IOMMU testing

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 11/26/25 7:45 AM, Tao Tang wrote:
> Add a minimal PCI test device designed to exercise IOMMU translation
> (such as ARM SMMUv3) without requiring guest firmware or OS. The device
> provides MMIO registers to configure and trigger DMA operations with
> controllable attributes (security state, address space), enabling
> deterministic IOMMU testing.
> 
> Key features:
> - Bare-metal IOMMU testing via simple MMIO interface
> - Configurable DMA attributes for security states and address spaces
> - Write-then-read verification pattern with automatic result checking
> 
> The device performs a deterministic DMA test pattern: write a known
> value (0x88888888) to a configured IOVA, read it back, and verify data
> integrity. Results are reported through a dedicated result register,
> eliminating the need for complex interrupt handling or driver
> infrastructure in tests.
> 
> This is purely a test device and not intended for production use or
> machine realism. It complements existing test infrastructure like
> pci-testdev but focuses specifically on IOMMU translation path
> validation.
> 
> Signed-off-by: Tao Tang <tangtao1634@phytium.com.cn>
> ---
>   docs/specs/index.rst            |   1 +
>   docs/specs/iommu-testdev.rst    | 109 +++++++++++++
>   hw/misc/Kconfig                 |   5 +
>   hw/misc/iommu-testdev.c         | 278 ++++++++++++++++++++++++++++++++
>   hw/misc/meson.build             |   1 +
>   hw/misc/trace-events            |  10 ++
>   include/hw/misc/iommu-testdev.h |  70 ++++++++
>   7 files changed, 474 insertions(+)
>   create mode 100644 docs/specs/iommu-testdev.rst
>   create mode 100644 hw/misc/iommu-testdev.c
>   create mode 100644 include/hw/misc/iommu-testdev.h
Overall, the test device looks sane and has a clear interface, that can 
be used for several iommu implementations, beyond Arm smmu.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>