linux-kernel - RE: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor

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Message-ID: <KL1P15301MB0008FB89237C3BB7A6D2BB39BF820@KL1P15301MB0008.APCP153.PROD.OUTLOOK.COM>
Date:   Wed, 16 Aug 2017 18:51:36 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     David Miller <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "Stephen Hemminger" <sthemmin@...rosoft.com>,
        "georgezhang@...are.com" <georgezhang@...are.com>,
        "jhansen@...are.com" <jhansen@...are.com>,
        "mkubecek@...e.cz" <mkubecek@...e.cz>,
        "asias@...hat.com" <asias@...hat.com>,
        "stefanha@...hat.com" <stefanha@...hat.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "cavery@...hat.com" <cavery@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "rolf.neugebauer@...ker.com" <rolf.neugebauer@...ker.com>,
        "dave.scott@...ker.com" <dave.scott@...ker.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "apw@...onical.com" <apw@...onical.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "joe@...ches.com" <joe@...ches.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dan.carpenter@...cle.com" <dan.carpenter@...cle.com>
Subject: RE: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor

> From: David Miller [mailto:davem@...emloft.net]
> Sent: Wednesday, August 16, 2017 11:07
> 
> From: Dexuan Cui <decui@...rosoft.com>
> Date: Tue, 15 Aug 2017 22:13:29 +0000
> 
> > +	/*
> > +	 * Check if we are running on VMware's hypervisor and bail out
> > +	 * if we are not.
> > +	 */
> > +	if (x86_hyper != &x86_hyper_vmware)
> > +		return -ENODEV;
> 
> This symbol is only available when CONFIG_HYPERVISOR_GUEST is defined.
> But this driver does not have a Kconfig dependency on that symbol so
> the build can fail in some configurations.

Hi David,
It looks typically modern Linux distros have CONFIG_HYPERVISOR_GUEST=y
by default, but I agree here we should make the dependency explicit:

--- a/drivers/misc/vmw_vmci/Kconfig
+++ b/drivers/misc/vmw_vmci/Kconfig
@@ -4,7 +4,7 @@

 config VMWARE_VMCI
        tristate "VMware VMCI Driver"
-       depends on X86 && PCI
+       depends on X86 && PCI && HYPERVISOR_GUEST
        help
          This is VMware's Virtual Machine Communication Interface.  It enables
          high-speed communication between host and guest in a virtual

And it looks it's not a bad thing to add the dependency, because some
existing VMWare drivers have had the dependency on CONFIG_HYPERVISOR_GUEST=y:
drivers/input/mouse/vmmouse.c (MOUSE_PS2_VMMOUSE)
drivers/misc/vmw_balloon.c (VMWARE_BALLOON)

Do you want me to submit a v2 for this patch with the Kconfig change?

-- Dexuan