Re: [PATCH v4 0/3] target/i386: Restrict system-specific features from user emulation

[Paolo Bonzini]

On 9/11/23 23:13, Philippe Mathieu-Daudé wrote:
> Too many system-specific code (and in particular KVM related)
> is pulled in user-only build. This led to adding unjustified
> stubs as kludge to unagressive linker non-optimizations.
>
> This series restrict x86 system-specific features to sysemu,
> so we don't require any stub, and remove all x86 KVM declarations
> from user emulation code (to trigger compile failure instead of
> link one).
>
> Philippe Mathieu-Daudé (3):
>    target/i386: Check kvm_hyperv_expand_features() return value
>    RFC target/i386: Restrict system-specific features from user emulation
>    target/i386: Prohibit target specific KVM prototypes on user emulation

At least, patch 2 should be changed so that the #ifdef'ery is done at a 
higher level.

However, the dependency of user-mode emulation on KVM is really an 
implementation detail of QEMU.  It's very much baked into linux-user and 
hard to remove, but I'm not sure it's a good idea to add more #ifdef 
CONFIG_USER_ONLY around KVM code.

Paolo