On 10/13/25 06:01, Alejandro Vallejo wrote: > On Wed Oct 8, 2025 at 6:04 PM CEST, Jan Beulich wrote: >> On 30.09.2025 14:52, 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 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. >> >> What is "paravirtualized I/O" about in this context? > > Hypervisor-assisted IPIs, TLB flushes, etc. Or so I understood back when I > said > that looked ok. I see there could be confusion with Xen PV device protocols, > but as far as the user of the help message is concerned it makes no > difference. > > One could even remove the examples and leave it as "... for Hyper-V guests. > This > is to...". They are truly inconsequential. > > All that matters is that (modern) Windows won't run without it, and that it > provides some indeterminate hypervisor-provided assists to try to reduce some > virtualization overheads.
Qubes OS doesn't expose Viridian at all, which is why it wasn't vulnerable to XSA-472. It still runs Windows guests just fine. -- Sincerely, Demi Marie Obenour (she/her/hers)
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