On Tue, Sep 30, 2025 at 12:49:21PM -0700, H. Peter Anvin wrote: > /* Xen code, stub sets CF = 1 on failure */ > > 0: e8 xx xx xx xx call asm_xen_pv_wrmsr > 5: 73 03 jnc 0xa > 7: 0f 0b ud2 > 9: 90 nop > a: > > The trap point even ends up in the same place! UD2 can be any 1-, 2-, or > 3-byte trapping instruction.
Please don't rely on flags to be retained by RET. The various mitigations have trouble with that.
