On 31/03/16 16:37, Alex Bennée wrote: > Sergey Fedorov <serge.f...@gmail.com> writes: >> Looks like no matter which approach we use, it's ultimately necessary to >> ensure all CPUs have exited from translated code before the translation >> buffer may be safely flushed. > One approach would be to have multiple translation contexts with their > own buffers and then you can safely flush TBs if no vCPUs are currently > executing in those regions. But I suspect that is a much more complex > future optimisation.
Yes, this is much more complex and its performance impact should be investigated. > Having said that is it safe to flush TBs from a given page if we know > no vCPUs are currently executing in that page? As the execution loop has > to exit the chained TBs as we cross page boundaries we could just keep > account of which vCPUs are currently in which page. It should be safe to invalidate a TB while some other CPU is executing its translated code. But it should be guaranteed that no CPU execute any old TB after tb_flush() since we're going to start reusing those TBs. I see how TB cannot be patched if it spans two pages, is there any on when TCG goto_tb can be generated? Kind regards, Sergey
