On 9/11/2025 6:42 PM, Chao Gao wrote:
@@ -4941,6 +4947,24 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len, int
if (ctxt->d == 0)
return EMULATION_FAILED;
+ if (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_CET) {
+ u64 u_cet, s_cet;
+ bool stop_em;
+
+ if (ctxt->ops->get_msr(ctxt, MSR_IA32_U_CET, &u_cet) ||
+ ctxt->ops->get_msr(ctxt, MSR_IA32_S_CET, &s_cet))
+ return EMULATION_FAILED;
+
+ stop_em = ((u_cet & CET_SHSTK_EN) || (s_cet & CET_SHSTK_EN)) &&
+ (opcode.flags & ShadowStack);
+
+ stop_em |= ((u_cet & CET_ENDBR_EN) || (s_cet & CET_ENDBR_EN)) &&
+ (opcode.flags & IndirBrnTrk);
Why don't check CPL here? Just for simplicity?
I think so. This is a corner case and we don't want to make it very precise
(and thus complex). The reason is that no one had a strong opinion on whether
to do the CPL check or not. I asked the same question before [*], but I don't
have a strong opinion on this either.
I'm OK with it.
But I think we should at least mention it in the change log. So people
will know that CPL check is skipped intentionally and maintainers are OK
with it so the patch was merged, when they dig the history.
[*]: https://lore.kernel.org/kvm/ZaSQn7RCRTaBK1bc@chao-email/
