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Subject: Re: [PATCH 1/5] arm64: entry: isb in el1_irq
References: <20180405171800.5648-1-ynorov@caviumnetworks.com>
 <20180405171800.5648-2-ynorov@caviumnetworks.com>
 <5036b99a-9faa-c220-27dd-e0d73f8b3fc7@arm.com>
 <20180406165402.nq3sabeku2mp3hpb@yury-thinkpad>
 <20180406172211.r42reit2bnpocab2@lakrids.cambridge.arm.com>
From: James Morse <james.morse@arm.com>
Message-ID: <1ef13053-c3eb-deea-a4cc-67723fdf47f8@arm.com>
Date: Fri, 6 Apr 2018 18:30:50 +0100
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To: Mark Rutland <mark.rutland@arm.com>
Cc: Yury Norov <ynorov@caviumnetworks.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Will Deacon <will.deacon@arm.com>, Chris Metcalf <cmetcalf@mellanox.com>, Christopher Lameter <cl@linux.com>, Russell King - ARM Linux <linux@armlinux.org.uk>, Steven Rostedt <rostedt@goodmis.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Catalin Marinas <catalin.marinas@arm.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Alexey Klimov <klimov.linux@gmail.com>, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org

Hi Mark,

On 06/04/18 18:22, Mark Rutland wrote:
> Digging a bit, I also thing that our ct_user_exit and ct_user_enter
> usage is on dodgy ground today.

[...]

> I think similar applies to SDEI; we don't negotiate with RCU prior to
> invoking handlers, which might need RCU.

The arch code's __sdei_handler() calls nmi_enter() -> rcu_nmi_enter(), which
does a rcu_dynticks_eqs_exit().


Thanks,

James