[SRU][U/O][N][PATCH 1/1] UBUNTU: [Config] Set IOMMU_DEFAULT_DMA_STRICT=n and IOMMU_DEFAULT_DMA_LAZY=yes for s390x

[Kleber Souza]

On 03.07.24 11:19, frank.heimes at canonical.com wrote:
> From: Frank Heimes <frank.heimes at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2071471
> 
> Align the Ubuntu kernel config options to the modified defaults from upstream
> b2b97a62f055 "Revert "s390: update defconfigs""
> and set IOMMU_DEFAULT_DMA_STRICT=n and IOMMU_DEFAULT_DMA_LAZY=yes for s390x.
> This is required to avoid significant PCIe network throughput degradation
> with the changed dma-iommu implementation in c76c067e488c
> "s390/pci: Use dma-iommu layer" since v6.7.
> 
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>

LGTM. Performance improvement on s390x confirmed by the vendor.


Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

Thanks

> ---
>   debian.master/config/annotations | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/debian.master/config/annotations b/debian.master/config/annotations
> index dbecd432d4a6..6b039eb3b264 100644
> --- a/debian.master/config/annotations
> +++ b/debian.master/config/annotations
> @@ -345,6 +345,12 @@ CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON     note<'LP: #1951440'>
>   CONFIG_IOMMU_DEBUGFS                            policy<{'amd64': 'n', 'arm64': 'n', 'armhf': 'n', 'ppc64el': 'n', 'riscv64': 'n', 's390x': 'n'}>
>   CONFIG_IOMMU_DEBUGFS                            note<'LP: #1861057'>
>   
> +CONFIG_IOMMU_DEFAULT_DMA_LAZY                   policy<{'amd64': 'y', 'arm64': 'n', 'armhf': 'n', 'ppc64el': 'n', 'riscv64': 'n', 's390x': 'y'}>
> +CONFIG_IOMMU_DEFAULT_DMA_LAZY                   note<'LP: #2071471'>
> +
> +CONFIG_IOMMU_DEFAULT_DMA_STRICT                 policy<{'amd64': 'n', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y', 's390x': 'n'}>
> +CONFIG_IOMMU_DEFAULT_DMA_STRICT                 note<'LP: #2071471'>
> +
>   CONFIG_IPMMU_VMSA                               policy<{'arm64': 'n', 'armhf': 'n', 'riscv64': '-'}>
>   CONFIG_IPMMU_VMSA                               note<'LP: #1718734'>
>   
> @@ -6734,8 +6740,6 @@ CONFIG_IOMMUFD                                  policy<{'amd64': 'm', 'arm64': '
>   CONFIG_IOMMUFD_DRIVER                           policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y'}>
>   CONFIG_IOMMU_API                                policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y', 's390x': 'y'}>
>   CONFIG_IOMMU_DEBUG                              policy<{'amd64': 'n'}>
> -CONFIG_IOMMU_DEFAULT_DMA_LAZY                   policy<{'amd64': 'y', 'arm64': 'n', 'armhf': 'n', 'ppc64el': 'n', 'riscv64': 'n', 's390x': 'n'}>
> -CONFIG_IOMMU_DEFAULT_DMA_STRICT                 policy<{'amd64': 'n', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y', 's390x': 'y'}>
>   CONFIG_IOMMU_DEFAULT_PASSTHROUGH                policy<{'amd64': 'n', 'arm64': 'n', 'armhf': 'n', 'ppc64el': 'n', 'riscv64': 'n', 's390x': 'n'}>
>   CONFIG_IOMMU_DMA                                policy<{'amd64': 'y', 'arm64': 'y', 's390x': 'y'}>
>   CONFIG_IOMMU_HELPER                             policy<{'amd64': 'y', 'ppc64el': 'y', 's390x': 'y'}>