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> > > > - this_cpu(stubs.addr) = alloc_stub_page(smp_processor_id(), > > - &this_cpu(stubs).mfn); > > - BUG_ON(!this_cpu(stubs.addr)); > > + init_stub(); > > While I hate to nitpick further, "stubs".  There are 4 per CPU, and I'm > reasonably sure we're consistently plural elsewhere. Funny you ask - I had it as "stubs" initially, but then realized the existing function is named alloc_stub_page(), and hence switched back to use "stub" as that seemed more inline with the existing usage. I will adjust on commit. > Otherwise (and with Jan's grammar note in the commit message too), > Reviewed-by: Andrew Cooper Thanks, yes, that's been adjusted in the commit message. > One further thought, which would be for a followup patch if we decide to > do it. > > We do now use UDB for bugframes.  It's also marginally better than INT3 > because if we do ever end up finding ourselves executing it, because > we'll #UD on the first one, rather than try to brute force our way > through the #BPs printing a log message per instruction. > > One thing I didn't check and I really need to is whether UDB has the > same speculation-halting properties that UD2 has.  It's not a guarantee, > given that the encoding is valid in other modes. Hm, yes, let's see if I find some time to change it, or whether someone else beats me to it :). Roger.