Re: [PATCH] x86/hvm: add HVM-specific Kconfig

[Denis Mukhin <dmkhn@xxxxxxxxx>]

On Friday, February 7th, 2025 at 2:03 PM, dmkhn@xxxxxxxxx <dmkhn@xxxxxxxxx> 
wrote:

> 
> 
> Add separate menu for configuring HVM build-time settings to help organizing
> HVM-specific options.
> 
> Signed-off-by: Denis Mukhin dmukhin@xxxxxxxx

Can I get a review please?

> 
> 
> ---
> Link to the original patch:
> https://lore.kernel.org/xen-devel/20250103-vuart-ns8250-v3-v1-20-c5d36b31d66c@xxxxxxxx/
> ---
> ---
> xen/arch/x86/Kconfig | 76 +---------------------------------------
> xen/arch/x86/hvm/Kconfig | 73 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 74 insertions(+), 75 deletions(-)
> create mode 100644 xen/arch/x86/hvm/Kconfig
> 
> diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
> index 9cdd04721a..37362c205d 100644
> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -30,7 +30,6 @@ config X86
> select HAS_SCHED_GRANULARITY
> select HAS_UBSAN
> select HAS_VMAP
> - select HAS_VPCI if HVM
> select NEEDS_LIBELF
> 
> config ARCH_DEFCONFIG
> @@ -107,42 +106,7 @@ config PV_LINEAR_PT
> 
> If unsure, say Y.
> 
> -config HVM
> - bool "HVM support"
> - depends on !PV_SHIM_EXCLUSIVE
> - default !PV_SHIM
> - select COMPAT
> - select IOREQ_SERVER
> - select MEM_ACCESS_ALWAYS_ON
> - help
> - Interfaces to support HVM domains. HVM domains require hardware
> - virtualisation extensions (e.g. Intel VT-x, AMD SVM), but can boot
> - guests which have no specific Xen knowledge.
> -
> - This option is needed if you want to run HVM or PVH domains.
> -
> - If unsure, say Y.
> -
> -config AMD_SVM
> - bool "AMD-V" if EXPERT
> - depends on HVM
> - default y
> - help
> - Enables virtual machine extensions on platforms that implement the
> - AMD Virtualization Technology (AMD-V).
> - If your system includes a processor with AMD-V support, say Y.
> - If in doubt, say Y.
> -
> -config INTEL_VMX
> - bool "Intel VT-x" if EXPERT
> - depends on HVM
> - default y
> - select ARCH_VCPU_IOREQ_COMPLETION
> - help
> - Enables virtual machine extensions on platforms that implement the
> - Intel Virtualization Technology (Intel VT-x).
> - If your system includes a processor with Intel VT-x support, say Y.
> - If in doubt, say Y.
> +source "arch/x86/hvm/Kconfig"
> 
> config XEN_SHSTK
> bool "Supervisor Shadow Stacks"
> @@ -201,25 +165,6 @@ config BIGMEM
> 
> If unsure, say N.
> 
> -config HVM_FEP
> - bool "HVM Forced Emulation Prefix support (UNSUPPORTED)" if UNSUPPORTED
> - default DEBUG
> - depends on HVM
> - help
> -
> - Compiles in a feature that allows HVM guest to arbitrarily
> - exercise the instruction emulator.
> -
> - This feature can only be enabled during boot time with
> - appropriate hypervisor command line option. Please read
> - hypervisor command line documentation before trying to use
> - this feature.
> -
> - This is strictly for testing purposes, and not appropriate
> - for use in production.
> -
> - If unsure, say N.
> -
> config TBOOT
> bool "Xen tboot support (UNSUPPORTED)"
> depends on INTEL && UNSUPPORTED
> @@ -348,14 +293,6 @@ config HYPERV_GUEST
> 
> endif
> 
> -config MEM_PAGING
> - bool "Xen memory paging support (UNSUPPORTED)" if UNSUPPORTED
> - depends on HVM
> -
> -config MEM_SHARING
> - bool "Xen memory sharing support (UNSUPPORTED)" if UNSUPPORTED
> - depends on HVM
> -
> config REQUIRE_NX
> bool "Require NX (No eXecute) support"
> help
> @@ -372,17 +309,6 @@ config REQUIRE_NX
> was unavailable. However, if enabled, Xen will no longer boot on
> any CPU which is lacking NX support.
> 
> -config ALTP2M
> - bool "Alternate P2M support" if EXPERT
> - depends on INTEL_VMX
> - default y
> - help
> - Alternate-p2m allows a guest to manage multiple p2m guest physical
> - "memory views" (as opposed to a single p2m).
> - Useful for memory introspection.
> -
> - If unsure, stay with defaults.
> -
> endmenu
> 
> source "common/Kconfig"
> diff --git a/xen/arch/x86/hvm/Kconfig b/xen/arch/x86/hvm/Kconfig
> new file mode 100644
> index 0000000000..cbfeb5e4f4
> --- /dev/null
> +++ b/xen/arch/x86/hvm/Kconfig
> @@ -0,0 +1,73 @@
> +menuconfig HVM
> + bool "HVM support"
> + depends on !PV_SHIM_EXCLUSIVE
> + default !PV_SHIM
> + select COMPAT
> + select HAS_VPCI
> + select IOREQ_SERVER
> + select MEM_ACCESS_ALWAYS_ON
> + help
> + Interfaces to support HVM domains. HVM domains require hardware
> + virtualisation extensions (e.g. Intel VT-x, AMD SVM), but can boot
> + guests which have no specific Xen knowledge.
> +
> + This option is needed if you want to run HVM or PVH domains.
> +
> + If unsure, say Y.
> +
> +if HVM
> +
> +config AMD_SVM
> + bool "AMD-V" if EXPERT
> + default y
> + help
> + Enables virtual machine extensions on platforms that implement the
> + AMD Virtualization Technology (AMD-V).
> + If your system includes a processor with AMD-V support, say Y.
> + If in doubt, say Y.
> +
> +config INTEL_VMX
> + bool "Intel VT-x" if EXPERT
> + default y
> + select ARCH_VCPU_IOREQ_COMPLETION
> + help
> + Enables virtual machine extensions on platforms that implement the
> + Intel Virtualization Technology (Intel VT-x).
> + If your system includes a processor with Intel VT-x support, say Y.
> + If in doubt, say Y.
> +
> +config ALTP2M
> + bool "Alternate P2M support" if EXPERT
> + depends on INTEL_VMX
> + default y
> + help
> + Alternate-p2m allows a guest to manage multiple p2m guest physical
> + "memory views" (as opposed to a single p2m).
> + Useful for memory introspection.
> +
> + If unsure, stay with defaults.
> +
> +config MEM_PAGING
> + bool "Xen memory paging support (UNSUPPORTED)" if UNSUPPORTED
> +
> +config MEM_SHARING
> + bool "Xen memory sharing support (UNSUPPORTED)" if UNSUPPORTED
> +
> +config HVM_FEP
> + bool "HVM Forced Emulation Prefix support (UNSUPPORTED)" if UNSUPPORTED
> + default DEBUG
> + help
> + Compiles in a feature that allows HVM guest to arbitrarily
> + exercise the instruction emulator.
> +
> + This feature can only be enabled during boot time with
> + appropriate hypervisor command line option. Please read
> + hypervisor command line documentation before trying to use
> + this feature.
> +
> + This is strictly for testing purposes, and not appropriate
> + for use in production.
> +
> + If unsure, say N.
> +
> +endif
> --
> 2.34.1