Re: [PATCH v3] Drivers: hv: ioctl for self targeted passthrough hvcalls

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

On 11/19/2025 9:17 AM, Anirudh Rayabharam wrote:
> From: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
> 
> Allow MSHV_ROOT_HVCALL IOCTL on the /dev/mshv fd. This IOCTL would
> execute a passthrough hypercall targeting the root/parent partition
> i.e. HV_PARTITION_ID_SELF.
> 
> This will be useful for the VMM to query things like supported
> synthetic processor features, supported VMM capabiliites etc.
> 
> Since hypercalls targeting the host partition could potentially perform
> privileged operations, allow only a limited set of hypercalls. To begin
> with, allow only:
> 
> 	HVCALL_GET_PARTITION_PROPERTY
> 	HVCALL_GET_PARTITION_PROPERTY_EX
> 
> Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
> ---
> 
> v3: restricted the allowed self-targeted passthrough hypercalls to
>     smaller, carefully selected list.
> v2: rebased on latest hyperv-next
> 
> ---
>  drivers/hv/mshv_root_main.c | 47 ++++++++++++++++++++++++++++++-------
>  1 file changed, 38 insertions(+), 9 deletions(-)
> 
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>