Re: [Qemu-devel] [Migration][TCG] Page dirtying and migration in pure-QEMU VM mode

[Pavel Boldin]

A little self-update here.

1. It is seems to be enough to just flush TLB entries with the iothread lock held since the CPUs are stopped here.

2. The upstream version is not vulnerable to the bug due to the following code call path: ram_save_setup -> memory_global_dirty_log_start -> memory_region_transaction_commit -> tcg_commit -> CPU_FOREACH(cpu) tlb_flush(cpu, 1);.

The fix was introduced by the commit [1]

3. QEMU versions 2.0.0 (including Ubuntu's one) and 2.3.1 are vulnerable to the bug. I will report these as appropriate.

[1] http://git.qemu.org/?p=qemu.git;a=commit;h=6f6a5ef3e429f92f987678ea8c396aab4dc6aa19

Pavel
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