vvmx: Handle INVVPID_SINGLE_CONTEXT_RETAINING_GLOBAL properly

The feature is already advertised in NVPID_CAP_BITS, yet the handling
in nvmx_handle_invvpid() was missing.

Fixes: aa1b9dfdff ("nEPT: Expose EPT & VPID capablities to L1 VMM")
Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/vmx/vvmx.c

@@ -2053,6 +2053,7 @@ static int nvmx_handle_invvpid(struct cpu_user_regs *regs)
     case INVVPID_INDIVIDUAL_ADDR:
     case INVVPID_SINGLE_CONTEXT:
     case INVVPID_ALL_CONTEXT:
+    case INVVPID_SINGLE_CONTEXT_RETAINING_GLOBAL:
         hvm_asid_flush_vcpu_asid(&vcpu_nestedhvm(current).nv_n2asid);
         break;
     default: