On Nov 11, 2018, at 3:31 AM, Pavel Machek [off-list ref] wrote:

Hi!

quoted

quoted

+/*
+ * State component 12 is Control flow Enforcement kernel states
+ */
+struct cet_kernel_state {
+    u64 kernel_ssp;    /* kernel shadow stack */
+    u64 pl1_ssp;    /* ring-1 shadow stack */
+    u64 pl2_ssp;    /* ring-2 shadow stack */

Just write "privilege level" everywhere - not "ring".

Please just use word "ring". It is well estabilished terminology.

Which ring is priviledge level 1, given that we have SMM and
virtualization support?

To the contrary: CPL, DPL, and RPL are very well defined terms in the architecture manuals. “PL” is privilege level. PL 1 is very well defined.

SMM is SMM, full stop (unless dual mode or whatever it’s called is on, but AFAIK no one uses it).  VMX non-root CPL 1 is *still* privilege level 1.

In contrast, the security community likes to call SMM “ring -1”, which is cute, but wrong from a systems programmer view. For example, SMM’s CPL can still range from 0-3.

                                   Pavel
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