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 for <linuxppc-dev@lists.ozlabs.org> from <vaibhav@linux.ibm.com>;
 Wed, 1 Aug 2018 10:28:57 +0100
From: Vaibhav Jain <vaibhav@linux.ibm.com>
To: Frederic Barrat <fbarrat@linux.ibm.com>, linuxppc-dev@lists.ozlabs.org,
 npiggin@gmail.com
Cc: felix@linux.ibm.com, clombard@linux.ibm.com
Subject: Re: [PATCH] powerpc/64s/radix: Fix missing global invalidations when
 removing copro
In-Reply-To: <20180731132452.15994-1-fbarrat@linux.ibm.com>
References: <20180731132452.15994-1-fbarrat@linux.ibm.com>
Date: Wed, 01 Aug 2018 14:58:45 +0530
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Frederic Barrat <fbarrat@linux.ibm.com> writes:

> With the optimizations for TLB invalidation from commit 0cef77c7798a
> ("powerpc/64s/radix: flush remote CPUs out of single-threaded
> mm_cpumask"), the scope of a TLBI (global vs. local) can now be
> influenced by the value of the 'copros' counter of the memory context.
>
> When calling mm_context_remove_copro(), the 'copros' counter is
> decremented first before flushing. It may have the unintended side
> effect of sending local TLBIs when we explicitly need global
> invalidations in this case. Thus breaking any nMMU user in a bad and
> unpredictable way.
>
> Fix it by flushing first, before updating the 'copros' counter, so
> that invalidations will be global.
>
> Fixes: 0cef77c7798a ("powerpc/64s/radix: flush remote CPUs out of single-threaded mm_cpumask")
> Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
> ---
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>

-- 
Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Linux Technology Center, IBM India Pvt. Ltd.