On Mon, Mar 28, 2022, Nakajima, Jun wrote:

quoted

On Mar 28, 2022, at 1:16 PM, Andy Lutomirski [off-list ref] wrote:

On Thu, Mar 10, 2022 at 6:09 AM Chao Peng [off-list ref] wrote:

quoted

This is the v5 of this series which tries to implement the fd-based KVM
guest private memory. The patches are based on latest kvm/queue branch
commit:

 d5089416b7fb KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2

Can this series be run and a VM booted without TDX?  A feature like
that might help push it forward.

—Andy

Since the userspace VMM (e.g. QEMU) loses direct access to private memory of
the VM, the guest needs to avoid using the private memory for (virtual) DMA
buffers, for example. Otherwise, it would need to use bounce buffers, i.e. we
would need changes to the VM. I think we can try that (i.e. add only bounce
buffer changes). What do you think?

I would love to be able to test this series and run full-blown VMs without TDX or
SEV hardware.

The other option for getting test coverage is KVM selftests, which don't have an
existing guest that needs to be enlightened.  Vishal is doing work on that front,
though I think it's still in early stages.  Long term, selftests will also be great
for negative testing.