RE: [PATCH v3 5/5] x86/Kconfig: Add HYPERV_VTL_MODE

Michael Kelley (LINUX)
2023-03-26T15:16:24Z

From: Saurabh Sengar <ssengar@linux.microsoft.com> Sent: Monday, March 20, 2023 3:04 AM
>
> Add HYPERV_VTL_MODE Kconfig flag for VTL mode.
>
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
> arch/x86/Kconfig | 24 ++++++++++++++++++++++++
> arch/x86/hyperv/Makefile | 1 +
> 2 files changed, 25 insertions(+)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 453f462f6c9c..c3faaaea1e31 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -782,6 +782,30 @@ menuconfig HYPERVISOR_GUEST
>
> if HYPERVISOR_GUEST
>
> +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
> +

Is there a reason for putting this in arch/x86/Kconfig instead of in
drivers/hv/Kconfig under the "Microsoft Hyper-V guest support"
menu with the other Hyper-V settings? It seems like grouping
this with the other Hyper-V settings would make it easier to find,
unless there's some reason that doesn't work.

Michael

> config PARAVIRT
> bool "Enable paravirtualization code"
> depends on HAVE_STATIC_CALL
> diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
> index 5d2de10809ae..3a1548054b48 100644
> --- a/arch/x86/hyperv/Makefile
> +++ b/arch/x86/hyperv/Makefile
> @@ -1,6 +1,7 @@
> # SPDX-License-Identifier: GPL-2.0-only
> obj-y := hv_init.o mmu.o nested.o irqdomain.o ivm.o
> obj-$(CONFIG_X86_64) += hv_apic.o hv_proc.o
> +obj-$(CONFIG_HYPERV_VTL_MODE) += hv_vtl.o
>
> ifdef CONFIG_X86_64
> obj-$(CONFIG_PARAVIRT_SPINLOCKS) += hv_spinlock.o
> --
> 2.34.1