Re: [RFC PATCH 0/8] KVM: Prepopulate guest memory API

[David Matlack]

On 2024-03-01 09:28 AM, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> 
> Implementation:
> - x86 KVM MMU
>   In x86 KVM MMU, I chose to use kvm_mmu_do_page_fault().  It's not confined to
>   KVM TDP MMU.  We can restrict it to KVM TDP MMU and introduce an optimized
>   version.

Restricting to TDP MMU seems like a good idea. But I'm not quite sure
how to reliably do that from a vCPU context. Checking for TDP being
enabled is easy, but what if the vCPU is in guest-mode?

Perhaps we can just return an error out to userspace if the vCPU is in
guest-mode or TDP is disabled, and make it userspace's problem to do
memory mapping before loading any vCPU state.