From: Andrea Parri <parri.andrea@gmail.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: paulmck@kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org, mmaas@google.com,
hboehm@google.com, striker@us.ibm.com
Subject: Re: [RFC PATCH] membarrier: riscv: Provide core serializing command
Date: Fri, 4 Aug 2023 02:16:59 +0200 [thread overview]
Message-ID: <ZMxDe0gXKYbY5jgt@andrea> (raw)
In-Reply-To: <4bf79f06-4593-134a-04dd-b8f89e96a1b8@efficios.com>
> Can you double-check that riscv switch_mm() implies a fence.i or equivalent
> on the CPU doing the switch_mm ?
AFAICT, (riscv) switch_mm() does not guarantee that.
> AFAIR membarrier use of sync_core_before_usermode relies on switch_mm
> issuing a core serializing instruction.
I see. Thanks for the clarification.
BTW, the comment in __schedule() suggests that membarrier also relies on
switch_mm() issuing a full memory barrier: I don't think this holds.
Removing the "deferred icache flush" logic in switch_mm() - in favour of
a "plain" MB; FENCE.I - would meet both of these requirements.
Other ideas?
Andrea
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next prev parent reply other threads:[~2023-08-04 0:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-03 4:01 [RFC PATCH] membarrier: riscv: Provide core serializing command Andrea Parri
2023-08-03 15:45 ` Andrea Parri
2023-08-03 20:28 ` Mathieu Desnoyers
2023-08-04 0:16 ` Andrea Parri [this message]
2023-08-04 14:20 ` Mathieu Desnoyers
2023-08-04 14:59 ` Andrea Parri
2023-08-04 18:05 ` Mathieu Desnoyers
2023-08-04 19:16 ` Andrea Parri
2023-08-04 20:06 ` Mathieu Desnoyers
2023-08-07 13:19 ` Andrea Parri
2023-10-13 17:29 ` Palmer Dabbelt
2023-10-13 18:49 ` Mathieu Desnoyers
2023-10-16 18:27 ` Robbin Ehn
2023-11-09 19:24 ` Andrea Parri
2023-11-10 6:33 ` [PATCH 1/2] locking: Introduce prepare_sync_core_cmd() kernel test robot
2023-11-23 1:07 ` [RFC PATCH] membarrier: riscv: Provide core serializing command Charlie Jenkins
2023-11-23 2:13 ` Mathieu Desnoyers
2023-11-27 10:44 ` Andrea Parri
2023-11-23 6:52 ` Robbin Ehn
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