Re: [PATCH] target/ppc: Fix tlbie

[Leandro Lupori]

On 5/3/22 13:54, Cédric Le Goater wrote:

> On 5/3/22 18:39, Leandro Lupori wrote:
> > Commit 74c4912f097bab98 changed check_tlb_flush() to use
> > tlb_flush_all_cpus_synced() instead of calling tlb_flush() on each
> > CPU. However, as side effect of this, a CPU executing a ptesync
> > after a tlbie will have its TLB flushed only after exiting its
> > current Translation Block (TB).
> >
> > This causes memory accesses to invalid pages to succeed, if they
> > happen to be on the same TB as the ptesync.
>
> How did you track the issue ? Do you have a test case ?

I've initially found it with a hacked Linux kernel module that I was 
using to test tlbie behavior, before trying to improve its 
implementation to only invalidate the needed entries.

Now I've added a new test to those MMU tests from pnv-test, to be able 
to reproduce and test it more easily. I've not included it because it 
depends on other code from MMU tests and semihosting or attn. But you 
can check it here:

https://github.com/PPC64/qemu/commit/ccb60e4b950d1376b7f5d72843f6ce082a1a9edb 
(mmu_test_18)

Thanks,
Leandro

> Thanks,
>
> C.