i386/sev: Set CPU state to protected once SNP guest payload is finalized

Once KVM_SNP_LAUNCH_FINISH is called the vCPU state is copied into the
vCPU's VMSA page and measured/encrypted. Any attempt to read/write CPU
state afterward will only be acting on the initial data and so are
effectively no-ops.

Set the vCPU state to protected at this point so that QEMU don't
continue trying to re-sync vCPU data during guest runtime.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Message-ID: <20240530111643.1091816-18-pankaj.gupta@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/sev.c b/target/i386/sev.c
index ef2e592ca765c2b34ae2e8ca7359430a1e9ab581..e84e4395a53d3c2647f97b6e901debcc2a9fc890 100644 (file)
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -997,6 +997,7 @@ sev_snp_launch_finish(SevCommonState *sev_common)
         exit(1);
     }
 
+    kvm_mark_guest_state_protected();
     sev_set_guest_state(sev_common, SEV_STATE_RUNNING);
 
     /* add migration blocker */