On 16/09/20 00:44, Sean Christopherson wrote:
KVM doesn't have control of them. They are part of the guest's encrypted
state and that is what the guest uses. KVM can't alter the value that the
guest is using for them once the VMSA is encrypted. However, KVM makes
some decisions based on the values it thinks it knows. For example, early
on I remember the async PF support failing because the CR0 that KVM
thought the guest had didn't have the PE bit set, even though the guest
was in protected mode. So KVM didn't include the error code in the
exception it injected (is_protmode() was false) and things failed. Without
syncing these values after live migration, things also fail (probably for
the same reason). So the idea is to just keep KVM apprised of the values
that the guest has.
Ah, gotcha. Migrating tracked state through the VMSA would probably be ideal.
The semantics of __set_sregs() kinda setting state but not reaaaally setting
state would be weird.
How would that work with TDX?
Paolo
