Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Mark Brown <broonie@kernel.org>
Date:   Wed, 07 Jun 2023 21:30:51 +0100
Subject: [PATCH] arm64/fpsimd: Exit streaming mode when flushing tasks
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <20230607-arm64-flush-svcr-v1-1-7821a6199e0a@kernel.org>
To:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Anders Roxell <anders.roxell@linaro.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Mark Brown <broonie@kernel.org>
Precedence: bulk

Ensure there is no path where we might attempt to save SME state after we
flush a task by updating the SVCR register state as well as updating our
in memory state. I haven't seen a specific case where this is happening or
seen a path where it might happen but for the cost of a single low overhead
instruction it seems sensible to close the potential gap.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/fpsimd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 2fbafa5cc7ac..1627e0efe39a 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1649,6 +1649,7 @@ void fpsimd_flush_thread(void)
 
 		fpsimd_flush_thread_vl(ARM64_VEC_SME);
 		current->thread.svcr = 0;
+		sme_smstop_sm();
 	}
 
 	current->thread.fp_type = FP_STATE_FPSIMD;

---
base-commit: 44c026a73be8038f03dbdeef028b642880cf1511
change-id: 20230607-arm64-flush-svcr-47cc76a8cbbc

Best regards,
-- 
Mark Brown <broonie@kernel.org>