linux-kernel - [PATCH v1 2/3] Documentation: Update the new SIGBUS behaviour for tasks

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Date:   Wed, 18 Nov 2020 10:49:33 +1100
From:   Balbir Singh <sblbir@...zon.com>
To:     <tglx@...utronix.de>, <mingo@...hat.com>
CC:     <peterz@...radead.org>, <linux-kernel@...r.kernel.org>,
        <keescook@...omium.org>, Balbir Singh <sblbir@...zon.com>
Subject: [PATCH v1 2/3] Documentation: Update the new SIGBUS behaviour for tasks

Update the documentation to mention that a SIGBUS will be sent
to tasks that opt-into L1D flushing and execute on non-SMT cores.

Signed-off-by: Balbir Singh <sblbir@...zon.com>
---
To be applied on top of tip commit id
767d46ab566dd489733666efe48732d523c8c332

 Documentation/admin-guide/hw-vuln/l1d_flush.rst | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/hw-vuln/l1d_flush.rst b/Documentation/admin-guide/hw-vuln/l1d_flush.rst
index adc4ecc72361..c6a0713c8271 100644
--- a/Documentation/admin-guide/hw-vuln/l1d_flush.rst
+++ b/Documentation/admin-guide/hw-vuln/l1d_flush.rst
@@ -63,8 +63,8 @@ This can be addressed by controlled placement of processes on physical CPU
 cores or by disabling SMT. See the relevant chapter in the L1TF mitigation
 document: :ref:`Documentation/admin-guide/hw-vuln/l1tf.rst <smt_control>`.
 
-**NOTE** : Checks have been added to ensure that the prctl API associated
+**NOTE** : Checks have been added to ensure that the L1D flush associated
 with the opt-in will work only when the task affinity of the task opting
-in, is limited to cores running in non-SMT mode. The same checks are made
-when L1D is flushed.  Changing the affinity after opting in, would result
-in flushes not working on cores that are in non-SMT mode.
+in, is limited to cores running in non-SMT mode. Changing the affinity after
+opting in, would result in the task getting a SIGBUS when it executes on
+the flush is needed and the task is executing on the non-SMT core.
-- 
2.17.1