RE: [PATCH 06/11] Drivers: hv: Make sint vector architecture neutral in MSHV_VTL

Michael Kelley
2026-04-01T16:57:48Z

From: Naman Jain <namjain@linux.microsoft.com> Sent: Monday, March 16, 2026 5:13 AM
>
> Generalize Synthetic interrupt source vector (sint) to use
> vmbus_interrupt variable instead, which automatically takes care of
> architectures where HYPERVISOR_CALLBACK_VECTOR is not present (arm64).

Sashiko AI raised an interesting question about the startup timing --
whether the vmbus_platform_driver_probe() is guaranteed to have
set vmbus_interrupt before the VTL functions below run and use it.
What causes the mshv_vtl.ko module to be loaded, and hence run
mshv_vtl_init()?

>
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
> ---
> drivers/hv/mshv_vtl_main.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
> index b607b6e7e121..91517b45d526 100644
> --- a/drivers/hv/mshv_vtl_main.c
> +++ b/drivers/hv/mshv_vtl_main.c
> @@ -234,7 +234,7 @@ static void mshv_vtl_synic_enable_regs(unsigned int cpu)
> union hv_synic_sint sint;
>
> sint.as_uint64 = 0;
> - sint.vector = HYPERVISOR_CALLBACK_VECTOR;
> + sint.vector = vmbus_interrupt;
> sint.masked = false;
> sint.auto_eoi = hv_recommend_using_aeoi();
>
> @@ -753,7 +753,7 @@ static void mshv_vtl_synic_mask_vmbus_sint(void *info)
> const u8 *mask = info;
>
> sint.as_uint64 = 0;
> - sint.vector = HYPERVISOR_CALLBACK_VECTOR;
> + sint.vector = vmbus_interrupt;
> sint.masked = (*mask != 0);
> sint.auto_eoi = hv_recommend_using_aeoi();
>
> --
> 2.43.0
>

Assuming there's no timing problem vs. the VMBus driver,

Reviewed-by: Michael Kelley <mhklinux@outlook.com>