On Thu Sep 18, 2025 at 7:13 PM CEST, Grygorii Strashko wrote: > > > On 18.09.25 18:19, Jan Beulich wrote: >> On 18.09.2025 17:15, Grygorii Strashko wrote: >>> On 16.09.25 16:41, Grygorii Strashko wrote: >>>> --- a/xen/arch/x86/hvm/Kconfig >>>> +++ b/xen/arch/x86/hvm/Kconfig >>>> @@ -62,6 +62,16 @@ config ALTP2M >>>> >>>> If unsure, stay with defaults. >>>> >>>> +config HVM_VIRIDIAN >>>> + bool "Hyper-V enlightenments for guests" if EXPERT >>>> + default y >>>> + help >>>> + Support optimizations for Hyper-V guests such as faster hypercalls, >>>> + efficient timer and interrupt handling, and enhanced paravirtualized >>>> + I/O. This is to improve performance and compatibility of Windows VMs. >>>> + >>>> + If unsure, say Y. >>>> + >>> >>> Actually there is a question for x86 Experts - >>> Does it make sense to have HVM_VIRIDIAN enabled without enabled >>> AMD_SVM/INTEL_VMX Virtualization extensions? >> >> It makes as much or as little sense as HVM=y with both of the ones you >> mention >> turned off. Iirc Andrew in particular wanted to permit such configurations, >> to >> allow to prove the (abstract) correctness of building them, even if the >> resulting hypervisor may be of little use. > > I've been thinking about adding "depends on AMD_SVM || INTEL_VMX" > to cleanly note dependency.
If anything, it would be CONFIG_HVM. Pretty sure one can't sanely implement minimal viridian fully on PV. Certain extensions assume some degree of hardware emulation. > It's very hard to understand dependencies within x86 code :( They are very sparsely documented, you're not wrong. Cheers, Alejandro
