Re: [PATCH v10 20/41] KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes
Ackerley Tng <[email protected]>
| Newsgroups | gmane.comp.emulators.kvm.devel,gmane.linux.kernel,gmane.linux.documentation,gmane.linux.kernel.mm |
|---|---|
| Message-ID | <CAEvNRgHpy52iynKfXeEkyCixhhu0_Hnu5jSNT8i+BNxvEoG7Cg@mail.gmail.com> |
"David Hildenbrand (Arm)" <[email protected]> writes: > On 8/7/26 23:52, Ackerley Tng via B4 Relay wrote: >> From: Ackerley Tng <[email protected]> >> >> >> [...snip...] >> >> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig >> index abb108886733a..2c3c22aeafa54 100644 >> --- a/arch/x86/kvm/Kconfig >> +++ b/arch/x86/kvm/Kconfig >> @@ -81,13 +81,21 @@ config KVM_WERROR >> If in doubt, say "N". >> >> config KVM_VM_MEMORY_ATTRIBUTES >> - bool >> + bool "Enable per-VM PRIVATE vs. SHARED attributes (for CoCo VMs)" >> + depends on KVM_SW_PROTECTED_VM || KVM_INTEL_TDX || KVM_AMD_SEV >> + help >> + Enable support for tracking PRIVATE vs. SHARED memory using per-VM >> + memory attributes. Using per-VM attributes is deprecated in favor of >> + tracking PRIVATE state in guest_memfd. Select this if you need to run >> + CoCo VMs using a VMM that doesn't support guest_memfd memory >> + attributes. >> + >> + If unsure, say N. > > Hm, does that imply that a distribution that must support both, cannot ship a > single kernel? > Did you mean this as a documentation comment? Should the above read: help Enable support for tracking PRIVATE vs. SHARED memory using per-VM memory attributes. Using per-VM attributes is deprecated in favor of tracking PRIVATE state in guest_memfd. Select this if you need to run CoCo VMs using a VMM that doesn't support guest_memfd memory - attributes. + attributes. Select this to defer selection of where PRIVATE vs. SHARED + attributes are tracked to KVM module load time, where + gmem_in_place_conversion can be specified as a module parameter. If unsure, say N. I think we should do _without_ the above clarification since using VM memory attributes for shared/private status is intended to be deprecated. Is it fair to say distributions should not support both, and if they _must_ support both, they need to read code to figure this out? > -- > Cheers, > > David