Emilio G. Cota <c...@braap.org> writes: > On Tue, Sep 27, 2016 at 18:16:45 +0200, Paolo Bonzini wrote: >> Anyhow, the next step is to merge either cmpxchg-based atomics >> or iothread-free single-threaded TCG. Either will do. :) >> >> I think that even iothread-free single-threaded TCG requires this >> TLB stuff, because the iothread's address_space_write (and hence >> invalidate_and_set_dirty) can race against the TCG thread's >> code generation. > > What's a quick-and-dirty way to disable the fast-path TLB lookups? > Alex: you told me the monitor has an option for this, but I can't > find it. I'm looking for something that'd go in tcg/i386 to simply > bypass the fast path.
Hack up tlb_set_page_with_attrs() to always set one of the TLB_FOO bits (you might want to invent a new one as the other do have meanings). > > Forcing the slow TLB lookup would be an easy way to then implement > a per-TLB seqlock. I think TLB corruption might explain the crashes I > see when booting Ubuntu in a many-core guest (running on a many-core > host). TLB corruption is suspected but I've never come up with a clean test case to force it. I find heavy compiles in a system image can do it but my SMC torture test never crashes. > > Thanks, > > Emilio -- Alex Bennée
