Re: [PATCH v2 4/5] hv: Enable vmbus driver for nested root partition

[Wei Liu <wei.liu@kernel.org>]

On Thu, Nov 03, 2022 at 03:30:35AM +0000, Michael Kelley (LINUX) wrote:
> From: Jinank Jain <jinankjain@linux.microsoft.com> Sent: Wednesday, November 2, 2022 9:36 AM
> > 
> > Currently VMBus driver is not initialized for root partition but we need
> > to enable the VMBus driver for nested root partition. This is required
> > to expose VMBus devices to the L2 guest in the nested setup.
> > 
> > Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> > ---
> >  drivers/hv/vmbus_drv.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index 8b2e413bf19c..2f0cf75e811b 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -2723,7 +2723,7 @@ static int __init hv_acpi_init(void)
> >  	if (!hv_is_hyperv_initialized())
> >  		return -ENODEV;
> > 
> > -	if (hv_root_partition)
> > +	if (hv_root_partition && !hv_nested)
> 
> Note that this code must compile and run when Linux is built
> to run as a guest on Hyper-V for ARM64.  There's currently
> no definition for hv_nested on the ARM64 side, so the compile
> will fail.  But per my comments in Patch 1 in this series, using the
> same technique as for hv_root_partition in hv_common.c should
> solve the ARM64 problem as well.

Jinank, you can use the following commands to cross-compile Linux.

  make ARCH=arm64 mshv_defconfig
  make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- Image

I think there are some follow-up patches in the internal tree which
fixed the arm64 build. You may be able to squash some of those patches
into series.

Thanks,
Wei.