Re: [PATCH v2 0/9] memory: Sanity checks memory transaction when releasing BQL

[Peter Xu <peterx@redhat.com>]

On Fri, Jul 23, 2021 at 03:34:35PM -0400, Peter Xu wrote:
> This is v2 of the series.  It was actually got forgotten for months until it
> was used to identify another potential issue of bql usage here (besides it
> could still be helpful when debugging a previous kvm dirty ring issue in that
> series):
> 
> https://lore.kernel.org/qemu-devel/CH0PR02MB7898BBD73D0F3F7D5003BB178BE19@CH0PR02MB7898.namprd02.prod.outlook.com/
> 
> So I figured maybe it's still worth to have it, hence a repost.
> 
> There're some changes against v1:
> 
>   - patch "cpus: Introduce qemu_cond_timedwait_iothread()" is dropped because
>     it's introduced in another commit already (b0c3cf9407e64).
> 
>   - two more patches to move do_run_on_cpu() into softmmu/ to fix a linux-user
>     compliation issue.
> 
> Please review, thanks.
> 
> === Original Cover letter ===
> 
> This is a continuous work of previous discussion on memory transactions [1].
> It should be helpful to fail QEMU far earlier if there's misuse of BQL against
> the QEMU memory model.
> 
> One example is run_on_cpu() during memory commit.  That'll work previously, but
> it'll fail with very strange errors (like KVM ioctl failure due to memslot
> already existed, and it's not guaranteed to trigger constantly).  Now it'll
> directly fail when run_on_cpu() is called.
> 
> Please have a look, thanks.
> 
> [1] https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg03205.html

CC Phil too.

-- 
Peter Xu