On Wed, Oct 28, 2020 at 11:03:05AM -0700, Erdem Aktas wrote:
> I might be missing something here but I think what you say is only
> correct for the kvm_hypercall4 cases. All other functions use a
> smaller number of registers. #VC blindly assumes that all those
> registers are used in the vmcall and exposes them.
Right, I think we should fix that in the guest and zero out the unused
registers. VMMCALL can come from userspace after all, and the #VC
handler does not look at the hypercall numbers.
Further, on the host side KVM will unconditionally read out all 4
registers too, which requires us to set them valid in the GHCB.
Regards,
Joerg
