Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 3 Nov 2022 14:16:36 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     Jinank Jain <jinankjain@linux.microsoft.com>,
        Jinank Jain <jinankjain@microsoft.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "sthemmin@microsoft.com" <sthemmin@microsoft.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        Dexuan Cui <decui@microsoft.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>, "hpa@zytor.com" <hpa@zytor.com>,
        "arnd@arndb.de" <arnd@arndb.de>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "jpoimboe@kernel.org" <jpoimboe@kernel.org>,
        "seanjc@google.com" <seanjc@google.com>,
        "kirill.shutemov@linux.intel.com" <kirill.shutemov@linux.intel.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        "sathyanarayanan.kuppuswamy@linux.intel.com" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v2 4/5] hv: Enable vmbus driver for nested root partition
Message-ID: <Y2PNRKLTnbHUPPFq@liuwe-devbox-debian-v2>
References: <cover.1667406350.git.jinankjain@linux.microsoft.com>
 <b5ea40f7e84e17a4338a313ab74292a293b1efa4.1667406350.git.jinankjain@linux.microsoft.com>
 <BYAPR21MB16880A610264D54C141B7D79D7389@BYAPR21MB1688.namprd21.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <BYAPR21MB16880A610264D54C141B7D79D7389@BYAPR21MB1688.namprd21.prod.outlook.com>
Precedence: bulk

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.