Re: [PATCH for-8.0 07/29] accel/tcg: Honor atomicity of loads

[Richard Henderson]

On 11/22/22 06:35, Peter Maydell wrote:
> > +    /*
> > +     * Here we have the architectural atomicity of the operation.
> > +     * However, when executing in a serial context, we need no extra
> > +     * host atomicity in order to avoid racing.  This reduction
> > +     * avoids looping with cpu_loop_exit_atomic.
> > +     */
> > +    if (cpu_in_serial_context(env_cpu(env))) {
>
> Is it OK to use cpu_in_serial_context() here ? Even if
> there's no other vCPU executing in parallel, there might
> be device model code doing a memory write in the iothread,
> I think.

Well, it's no different from how we currently treat compare-and-swap expansion.  But you 
have a point -- we should probably be doing something with the iothread lock for both 
EXCP_ATOMIC and round-robin mode.


r~