From: Xenia Ragiadakou <burzalodowa@gmail.com>

Provide the user with configuration control over the cpu virtualization support
in Xen by making AMD_SVM and INTEL_VMX options user selectable.

To preserve the current default behavior, both options depend on HVM and
default to value of HVM.

To prevent users from unknowingly disabling virtualization support, make the
controls user selectable only if EXPERT is enabled.

No functional change intended.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
changes in v5:
- change kconfig option name SVM/VMX -> AMD_SVM/INTEL_VMX
changes in v3:
 - only tags added
changes in v2:
 - remove dependency of build options IOMMU/AMD_IOMMU on VMX/SVM options
---
 xen/arch/x86/Kconfig | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index eff9eedc19..f6a90d71fb 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -123,11 +123,25 @@ config HVM
 	  If unsure, say Y.
 
 config AMD_SVM
-	def_bool HVM
+	bool "AMD-V" if EXPERT
+	depends on HVM
+	default HVM
+	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
-	def_bool HVM
+	bool "Intel VT-x" if EXPERT
+	depends on HVM
+	default HVM
 	select ARCH_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 XEN_SHSTK
 	bool "Supervisor Shadow Stacks"
-- 
2.25.1

On 30.07.2024 12:41, Sergiy Kibrik wrote:
> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -123,11 +123,25 @@ config HVM
>  	  If unsure, say Y.
>  
>  config AMD_SVM
> -	def_bool HVM
> +	bool "AMD-V" if EXPERT
> +	depends on HVM
> +	default HVM
> +	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
> -	def_bool HVM
> +	bool "Intel VT-x" if EXPERT
> +	depends on HVM
> +	default HVM
>  	select ARCH_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.

Despite my earlier ack: It appears to make little sense to use "default HVM"
when there's also "depends on HVM". "default y" would be more clear imo, even
if just slightly.

Jan

01.08.24 14:39, Jan Beulich:
> On 30.07.2024 12:41, Sergiy Kibrik wrote:
>> --- a/xen/arch/x86/Kconfig
>> +++ b/xen/arch/x86/Kconfig
>> @@ -123,11 +123,25 @@ config HVM
>>   	  If unsure, say Y.
>>   
>>   config AMD_SVM
>> -	def_bool HVM
>> +	bool "AMD-V" if EXPERT
>> +	depends on HVM
>> +	default HVM
>> +	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
>> -	def_bool HVM
>> +	bool "Intel VT-x" if EXPERT
>> +	depends on HVM
>> +	default HVM
>>   	select ARCH_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.
> 
> Despite my earlier ack: It appears to make little sense to use "default HVM"
> when there's also "depends on HVM". "default y" would be more clear imo, even
> if just slightly.
> 

indeed, I'll fix it in v6 series

   -Sergiy