RE: [PATCH v4 4/5] Drivers: hv: Kconfig: Add HYPERV_VTL_MODE

[Michael Kelley (LINUX)]

From: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx> Sent: Tuesday, April 4, 2023 2:01 AM
> 
> Add HYPERV_VTL_MODE Kconfig flag for VTL mode.
> 
> Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/hv/Kconfig | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> index 0747a8f1fcee..511f2e012c59 100644
> --- a/drivers/hv/Kconfig
> +++ b/drivers/hv/Kconfig
> @@ -13,6 +13,30 @@ config HYPERV
>  	  Select this option to run Linux as a Hyper-V client operating
>  	  system.
> 
> +config HYPERV_VTL_MODE
> +	bool "Enable Linux to boot in VTL context"
> +	depends on X86_64 && HYPERV
> +	default n
> +	help
> +	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and
> +	  enlightenments offered to host and guest partitions which enables
> +	  the creation and management of new security boundaries within
> +	  operating system software.
> +
> +	  VSM achieves and maintains isolation through Virtual Trust Levels
> +	  (VTLs). Virtual Trust Levels are hierarchical, with higher levels
> +	  being more privileged than lower levels. VTL0 is the least privileged
> +	  level, and currently only other level supported is VTL2.
> +
> +	  Select this option to build a Linux kernel to run at a VTL other than
> +	  the normal VTL0, which currently is only VTL2.  This option
> +	  initializes the x86 platform for VTL2, and adds the ability to boot
> +	  secondary CPUs directly into 64-bit context as required for VTLs other
> +	  than 0.  A kernel built with this option must run at VTL2, and will
> +	  not run as a normal guest.
> +
> +	  If unsure, say N
> +
>  config HYPERV_TIMER
>  	def_bool HYPERV && X86
> 
> --
> 2.34.1

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>