Message-ID: <5003d5e8-a025-4827-b8a0-6fe11877421b@linux.microsoft.com>
Date: Thu, 28 Aug 2025 17:29:16 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: Mukesh Rathor <mrathor@...ux.microsoft.com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-input@...r.kernel.org, linux-hyperv@...r.kernel.org,
 netdev@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-scsi@...r.kernel.org, linux-fbdev@...r.kernel.org,
 linux-arch@...r.kernel.org, virtualization@...ts.linux.dev
Cc: maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
 tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, jikos@...nel.org,
 bentiss@...nel.org, kys@...rosoft.com, haiyangz@...rosoft.com,
 wei.liu@...nel.org, decui@...rosoft.com, dmitry.torokhov@...il.com,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, bhelgaas@...gle.com,
 James.Bottomley@...senPartnership.com, martin.petersen@...cle.com,
 gregkh@...uxfoundation.org, deller@....de, arnd@...db.de,
 sgarzare@...hat.com, horms@...nel.org
Subject: Re: [PATCH V0 1/2] hyper-v: Add CONFIG_HYPERV_VMBUS option

On 8/27/2025 5:59 PM, Mukesh Rathor wrote:
> Somehow vmbus driver is hinged on CONFIG_HYPERV. It appears this is initial
> code that did not get addressed when the scope of CONFIG_HYPERV went beyond
> vmbus. This commit creates a fine grained HYPERV_VMBUS option and updates
> drivers that depend on VMBUS.
> 

The commit message can be improved. The docs are helpful here:
https://docs.kernel.org/process/submitting-patches.html#describe-your-changes

In particular, some clearer reasons for the change.
e.g.
- CONFIG_HYPERV encompasses too much right now. It's not always clear what
  depends on builtin hyperv code and what depends on vmbus.

- Since there is so much builtin hyperv code, building CONFIG_HYPERV as a
  module doesn't make intuitive sense. Building vmbus support as a module does.

- There are actually some real scenarios someone may want to compile with
  CONFIG_HYPERV but without vmbus, like baremetal root partition.

FWIW I think it's a good idea, interested to hear what others think.

Nuno

> Signed-off-by: Mukesh Rathor <mrathor@...ux.microsoft.com>
> ---
>  drivers/gpu/drm/Kconfig        |  2 +-
>  drivers/hid/Kconfig            |  2 +-
>  drivers/hv/Kconfig             | 12 +++++++++---
>  drivers/hv/Makefile            |  2 +-
>  drivers/input/serio/Kconfig    |  4 ++--
>  drivers/net/hyperv/Kconfig     |  2 +-
>  drivers/pci/Kconfig            |  2 +-
>  drivers/scsi/Kconfig           |  2 +-
>  drivers/uio/Kconfig            |  2 +-
>  drivers/video/fbdev/Kconfig    |  2 +-
>  include/asm-generic/mshyperv.h |  8 +++++---
>  net/vmw_vsock/Kconfig          |  2 +-
>  12 files changed, 25 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index f7ea8e895c0c..58f34da061c6 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -398,7 +398,7 @@ source "drivers/gpu/drm/imagination/Kconfig"
>  
>  config DRM_HYPERV
>  	tristate "DRM Support for Hyper-V synthetic video device"
> -	depends on DRM && PCI && HYPERV
> +	depends on DRM && PCI && HYPERV_VMBUS
>  	select DRM_CLIENT_SELECTION
>  	select DRM_KMS_HELPER
>  	select DRM_GEM_SHMEM_HELPER
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index a57901203aeb..fe3dc8c0db99 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -1162,7 +1162,7 @@ config GREENASIA_FF
>  
>  config HID_HYPERV_MOUSE
>  	tristate "Microsoft Hyper-V mouse driver"
> -	depends on HYPERV
> +	depends on HYPERV_VMBUS
>  	help
>  	Select this option to enable the Hyper-V mouse driver.
>  
> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> index 2e8df09db599..08c4ed005137 100644
> --- a/drivers/hv/Kconfig
> +++ b/drivers/hv/Kconfig
> @@ -44,18 +44,24 @@ config HYPERV_TIMER
>  
>  config HYPERV_UTILS
>  	tristate "Microsoft Hyper-V Utilities driver"
> -	depends on HYPERV && CONNECTOR && NLS
> +	depends on HYPERV_VMBUS && CONNECTOR && NLS
>  	depends on PTP_1588_CLOCK_OPTIONAL
>  	help
>  	  Select this option to enable the Hyper-V Utilities.
>  
>  config HYPERV_BALLOON
>  	tristate "Microsoft Hyper-V Balloon driver"
> -	depends on HYPERV
> +	depends on HYPERV_VMBUS
>  	select PAGE_REPORTING
>  	help
>  	  Select this option to enable Hyper-V Balloon driver.
>  
> +config HYPERV_VMBUS
> +	tristate "Microsoft Hyper-V Vmbus driver"
> +	depends on HYPERV
> +	help
> +	  Select this option to enable Hyper-V Vmbus driver.
> +
>  config MSHV_ROOT
>  	tristate "Microsoft Hyper-V root partition support"
>  	depends on HYPERV && (X86_64 || ARM64)
> @@ -75,7 +81,7 @@ config MSHV_ROOT
>  
>  config MSHV_VTL
>  	tristate "Microsoft Hyper-V VTL driver"
> -	depends on X86_64 && HYPERV_VTL_MODE
> +	depends on X86_64 && HYPERV_VTL_MODE && HYPERV_VMBUS
>  	# Mapping VTL0 memory to a userspace process in VTL2 is supported in OpenHCL.
>  	# VTL2 for OpenHCL makes use of Huge Pages to improve performance on VMs,
>  	# specially with large memory requirements.
> diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
> index c53a0df746b7..050517756a82 100644
> --- a/drivers/hv/Makefile
> +++ b/drivers/hv/Makefile
> @@ -1,5 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
> -obj-$(CONFIG_HYPERV)		+= hv_vmbus.o
> +obj-$(CONFIG_HYPERV_VMBUS)	+= hv_vmbus.o
>  obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
>  obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
>  obj-$(CONFIG_MSHV_ROOT)		+= mshv_root.o
> diff --git a/drivers/input/serio/Kconfig b/drivers/input/serio/Kconfig
> index 17edc1597446..c7ef347a4dff 100644
> --- a/drivers/input/serio/Kconfig
> +++ b/drivers/input/serio/Kconfig
> @@ -276,8 +276,8 @@ config SERIO_OLPC_APSP
>  
>  config HYPERV_KEYBOARD
>  	tristate "Microsoft Synthetic Keyboard driver"
> -	depends on HYPERV
> -	default HYPERV
> +	depends on HYPERV_VMBUS
> +	default HYPERV_VMBUS
>  	help
>  	  Select this option to enable the Hyper-V Keyboard driver.
>  
> diff --git a/drivers/net/hyperv/Kconfig b/drivers/net/hyperv/Kconfig
> index c8cbd85adcf9..982964c1a9fb 100644
> --- a/drivers/net/hyperv/Kconfig
> +++ b/drivers/net/hyperv/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config HYPERV_NET
>  	tristate "Microsoft Hyper-V virtual network driver"
> -	depends on HYPERV
> +	depends on HYPERV_VMBUS
>  	select UCS2_STRING
>  	select NLS
>  	help
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 9a249c65aedc..7065a8e5f9b1 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -221,7 +221,7 @@ config PCI_LABEL
>  
>  config PCI_HYPERV
>  	tristate "Hyper-V PCI Frontend"
> -	depends on ((X86 && X86_64) || ARM64) && HYPERV && PCI_MSI && SYSFS
> +	depends on ((X86 && X86_64) || ARM64) && HYPERV_VMBUS && PCI_MSI && SYSFS
>  	select PCI_HYPERV_INTERFACE
>  	select IRQ_MSI_LIB
>  	help
> diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
> index 5522310bab8d..19d0884479a2 100644
> --- a/drivers/scsi/Kconfig
> +++ b/drivers/scsi/Kconfig
> @@ -589,7 +589,7 @@ config XEN_SCSI_FRONTEND
>  
>  config HYPERV_STORAGE
>  	tristate "Microsoft Hyper-V virtual storage driver"
> -	depends on SCSI && HYPERV
> +	depends on SCSI && HYPERV_VMBUS
>  	depends on m || SCSI_FC_ATTRS != m
>  	default HYPERV
>  	help
> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> index b060dcd7c635..6f86a61231e6 100644
> --- a/drivers/uio/Kconfig
> +++ b/drivers/uio/Kconfig
> @@ -140,7 +140,7 @@ config UIO_MF624
>  
>  config UIO_HV_GENERIC
>  	tristate "Generic driver for Hyper-V VMBus"
> -	depends on HYPERV
> +	depends on HYPERV_VMBUS
>  	help
>  	  Generic driver that you can bind, dynamically, to any
>  	  Hyper-V VMBus device. It is useful to provide direct access
> diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> index c21484d15f0c..72c63eaeb983 100644
> --- a/drivers/video/fbdev/Kconfig
> +++ b/drivers/video/fbdev/Kconfig
> @@ -1774,7 +1774,7 @@ config FB_BROADSHEET
>  
>  config FB_HYPERV
>  	tristate "Microsoft Hyper-V Synthetic Video support"
> -	depends on FB && HYPERV
> +	depends on FB && HYPERV_VMBUS
>  	select DMA_CMA if HAVE_DMA_CONTIGUOUS && CMA
>  	select FB_IOMEM_HELPERS_DEFERRED
>  	help
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index 1d2ad1304ad4..66c58c91b530 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -165,6 +165,7 @@ static inline u64 hv_generate_guest_id(u64 kernel_version)
>  
>  void __init hv_mark_resources(void);
>  
> +#if IS_ENABLED(CONFIG_HYPERV_VMBUS)
>  /* Free the message slot and signal end-of-message if required */
>  static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
>  {
> @@ -200,6 +201,10 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
>  	}
>  }
>  
> +extern int vmbus_interrupt;
> +extern int vmbus_irq;
> +#endif /* CONFIG_HYPERV_VMBUS */
> +
>  int hv_get_hypervisor_version(union hv_hypervisor_version_info *info);
>  
>  void hv_setup_vmbus_handler(void (*handler)(void));
> @@ -213,9 +218,6 @@ void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs));
>  void hv_remove_crash_handler(void);
>  void hv_setup_mshv_handler(void (*handler)(void));
>  
> -extern int vmbus_interrupt;
> -extern int vmbus_irq;
> -
>  #if IS_ENABLED(CONFIG_HYPERV)
>  /*
>   * Hypervisor's notion of virtual processor ID is different from
> diff --git a/net/vmw_vsock/Kconfig b/net/vmw_vsock/Kconfig
> index 56356d2980c8..8e803c4828c4 100644
> --- a/net/vmw_vsock/Kconfig
> +++ b/net/vmw_vsock/Kconfig
> @@ -72,7 +72,7 @@ config VIRTIO_VSOCKETS_COMMON
>  
>  config HYPERV_VSOCKETS
>  	tristate "Hyper-V transport for Virtual Sockets"
> -	depends on VSOCKETS && HYPERV
> +	depends on VSOCKETS && HYPERV_VMBUS
>  	help
>  	  This module implements a Hyper-V transport for Virtual Sockets.
>  

Powered by blists - more mailing lists