Hi David, On Wed, 22 Jan 2025 at 15:41, David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 22.01.25 16:35, David Hildenbrand wrote: > > On 22.01.25 16:27, Fuad Tabba wrote: > >> The purpose of this series is to serve as a potential base for > >> restricted mmap() support for guest_memfd [1]. It would allow > >> experimentation with what that support would be like, in the safe > >> environment of a new VM type used for testing. > >> > >> This series adds a new VM type for arm64, > >> KVM_VM_TYPE_ARM_SW_PROTECTED, analogous to the x86 > >> KVM_X86_SW_PROTECTED_VM. This type is to serve as a development > >> and testing vehicle for Confidential (CoCo) VMs. > >> > >> Similar to the x86 type, this is currently only for development > >> and testing. It's not meant to be used for "real" VMs, and > >> especially not in production. The behavior and effective ABI for > >> software-protected VMs is unstable. > >> > >> This series enables mmap() support for guest_memfd specifically > >> for the new software-protected VM type, only when explicitly > >> enabled in the config. > > > > Hi! > > > > IIUC, in this series, there is no "private" vs "shared" distinction, > > right? So all pages are mappable, and "conversion" does not exist? You're right. This is a simplified version of my series that allows mmaping of the new KVM_VM_TYPE_ARM_SW_PROTECTED vms to use for experimentation. Cheers, /fuad > > Ah, I spot: > > +#define kvm_arch_private_mem_inplace(kvm) \ > + (IS_ENABLED(CONFIG_KVM_GMEM_MAPPABLE) && \ > + ((kvm)->arch.vm_type & KVM_VM_TYPE_ARM_SW_PROTECTED)) > > Which makes me wonder, why don't we need the same way of making sure all > references/mappings are gone (+ new page type) when doing the shared -> > private conversion? Or is this somewhere in here where I didn't spot it yet? This is new to this series. The idea, based on a request from Patrick Roy, was to have a VM in arm64 we could use to experiment with. Since it allows the unconditional mmaping, it's only useful for experiments or for non-confidential VMs that want to use guest_memfd. This series isn't meant to replace the other one, more to supplement it and facilitate experimentation while that's going. Cheers, /fuad > -- > Cheers, > > David / dhildenb >
