Re: [PATCH for-8.1 0/6] Fix endianness issues in the intel-iommu device

[Michael S. Tsirkin]

On Wed, Aug 02, 2023 at 03:57:17PM +0200, Thomas Huth wrote:
> The intel-iommu device is currently unusable on big endian hosts.
> When doing something like this on a s390x host:
> 
>  wget 
> https://download.fedoraproject.org/pub/fedora/linux/releases/38/Server/x86_64/images/Fedora-Server-KVM-38-1.6.x86_64.qcow2
>  ./qemu-system-x86_64 -M q35 -device intel-iommu -m 2G \
>         -hda ~/Fedora-Server-KVM-38-1.6.x86_64.qcow2 -trace "vtd_*"
> 
> ... the guest kernel crashes during boot, complaining about some
> problems with the iommu, and you can see clearly in the traces that
> some values are wrong when compared to running this on a x86 host.
> 
> After spending quite some time hunting down the problems one by one,
> I think I now found them all - at least I can successfully boot the
> above kernel after I applied these patches.
> 
> Thomas Huth (6):
>   hw/i386/intel_iommu: Fix trivial endianness problems
>   hw/i386/intel_iommu: Fix endianness problems related to
>     VTD_IR_TableEntry
>   hw/i386/intel_iommu: Fix struct VTDInvDescIEC on big endian hosts
>   hw/i386/intel_iommu: Fix index calculation in
>     vtd_interrupt_remap_msi()
>   hw/i386/x86-iommu: Fix endianness issue in
>     x86_iommu_irq_to_msi_message()
>   include/hw/i386/x86-iommu: Fix struct X86IOMMU_MSIMessage for big
>     endian hosts
> 
>  hw/i386/intel_iommu_internal.h |  9 ++++++
>  include/hw/i386/intel_iommu.h  | 50 ++++++++++++++++++----------------
>  include/hw/i386/x86-iommu.h    | 50 ++++++++++++++++++----------------
>  hw/i386/intel_iommu.c          | 23 ++++++++++------
>  hw/i386/x86-iommu.c            |  2 +-
>  5 files changed, 76 insertions(+), 58 deletions(-)

I guess it's ok as a hack for 8.1. But we really need better
APIs. Annotating field endianness with __bitwise would be
a start.


> -- 
> 2.39.3