Re: [Qemu-devel] [PULL 15/36] memory: fix race between TCG and accesses to dirty bitmap

[Paolo Bonzini]

Il gio 12 set 2019, 19:43 Richard Henderson <address@hidden>
ha scritto:

> >>> Fortunately, in order to fix it, no change is required to the
> >>> vCPU thread.  However, the reader thread must delay the read after
> >>> the vCPU thread has finished the write.  This can be approximated
> >>> conservatively by run_on_cpu, which waits for the end of the current
> >>> translation block.
>
> If we are going to delay any read of the dirty flags until vCPU has
> completed
> any active TranslationBlock, then we can simplify the TCG operation so
> that we
> do not (ab)use the mmio path, and can promote this into the tlb slow path
> as we
> have recently done with watchpoints.


Uh, that's true and I agree it would be great. Die notdirty_mem_ops die...

Paolo