On 11.11.2025 18:54, Grygorii Strashko wrote:
> This series introduces possibility to disable 32-bit (COMPAT) interface 
> support
> in the following cases:

The use of plural here ...

>       - Only PVH domains are used
>       - Guests (OS) are started by using direct Direct Kernel Boot
>       - Guests (OS) are 64-bit and Guest early boot code, which is running not
>         in 64-bit mode, does not access Xen interfaces
>         (hypercalls, shared_info, ..)

... makes this an OR list, which I don't think would be correct. PVH domains,
for example, can well be 32-bit ones, can't they? Otoh the latter two points
look as if they really enumerate alternatives. Can you clarify please what is
meant?

Jan

> If above criterias are met the COMPAT HVM interface become unreachable and 
> can be disabled.
> Coverage reports analyze and adding guard (debug) exceptions in 
> hvm_hypercall/hvm_do_multicall_call
> and hvm_latch_shinfo_size() confirm that COMPAT HVM interface is unused for 
> safety use-case.
> 
> Grygorii Strashko (5):
>   x86: hvm: dm: factor out compat code under ifdefs
>   x86: hvm: compat: introduce vcpu_is_hcall_compat() helper
>   x86: hvm: factor out compat code under ifdefs
>   x86: pvh: allow to disable 32-bit interface support
>   x86: constify has_32bit_shinfo() if !CONFIG_COMPAT
> 
>  xen/arch/x86/hvm/Kconfig          | 19 +++++++++++++++-
>  xen/arch/x86/hvm/dm.c             |  2 ++
>  xen/arch/x86/hvm/hvm.c            | 22 +++++++++++++-----
>  xen/arch/x86/hvm/hypercall.c      | 37 +++++++++++++++++++++++--------
>  xen/arch/x86/hypercall.c          |  6 +----
>  xen/arch/x86/include/asm/domain.h |  3 ++-
>  xen/common/kernel.c               |  2 +-
>  xen/include/xen/sched.h           |  9 ++++++++
>  8 files changed, 78 insertions(+), 22 deletions(-)
> 


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