On 4/27/2026 11:09 AM, Michael Kelley wrote:

From: Naman Jain <redacted> Sent: Thursday, April 23, 2026 5:42 AM

quoted

Move hv_call_get_vp_registers() and hv_call_set_vp_registers()
declarations from drivers/hv/mshv.h to include/asm-generic/mshyperv.h.

These functions are defined in mshv_common.c and are going to be called
from both drivers/hv/ and arch/x86/hyperv/hv_vtl.c. The latter never
included mshv.h, relying on implicit declaration visibility. Moving the
declarations to the arch-generic Hyper-V header makes them properly
visible to all architecture-specific callers.

Provide static inline stubs returning -EOPNOTSUPP when neither
CONFIG_MSHV_ROOT nor CONFIG_MSHV_VTL is enabled.

Looking at the drivers/hv/Kconfig, it's possible to build with
CONFIG_HYPERV_VTL_MODE=y, but not CONFIG_MSHV_VTL. In such a
case, mshv_common.o doesn't get built, which is why the stubs are
needed. Is such a configuration desirable for some scenarios?

I wonder if having CONFIG_HYPERV_VTL_MODE force the building of
mshv_common.o would be a better approach. Then the stubs wouldn't
be needed. The "ifneq" statement in drivers/hv/Makefile could use
CONFIG_HYPERV_VTL_MODE instead of CONFIG_MSHV_VTL, and
everything would be good since CONFIG_MSHV_VTL depends on
CONFIG_HYPERV_VTL_MODE.

This looks good. I'll try this and make the changes. In case there are 
some challenges with that, I'll revert back.


Regards,
Naman