linux-kernel - [PATCH v2 2/2] arm64/sme: Restore SMCR

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Message-Id: <20240203-arm64-sme-resume-v2-2-a1fbaddc4425@kernel.org>
Date: Sat, 03 Feb 2024 13:00:41 +0000
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>
Cc: Dave Martin <Dave.Martin@....com>, 
 Jackson Cooper-Driver <Jackson.Cooper-Driver@....com>, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Mark Brown <broonie@...nel.org>
Subject: [PATCH v2 2/2] arm64/sme: Restore SMCR_EL1.EZT0 on exit from
 suspend

The fields in SMCR_EL1 reset to an architecturally UNKNOWN value. Since we
do not otherwise manage the traps configured in this register at runtime we
need to reconfigure them after a suspend in case nothing else was kind
enough to preserve them for us. Do so for SMCR_EL1.EZT0.

Fixes: d4913eee152d (arm64/sme: Add basic enumeration for SME2)
Reported-by: Jackson Cooper-Driver <Jackson.Cooper-Driver@....com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/kernel/fpsimd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 8d2a5824d5d3..7a7c056f0647 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1320,6 +1320,8 @@ void sme_suspend_exit(void)
 
 	if (system_supports_fa64())
 		smcr |= SMCR_ELx_FA64;
+	if (system_supports_sme2())
+		smcr |= SMCR_ELx_EZT0;
 
 	write_sysreg_s(smcr, SYS_SMCR_EL1);
 	write_sysreg_s(0, SYS_SMPRI_EL1);

-- 
2.30.2