arm64/sme: Restore SMCR_EL1.EZT0 on exit from suspend

[ Upstream commit d7b77a0d565b048cb0808fa8a4fb031352b22a01 ]

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@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240213-arm64-sme-resume-v3-2-17e05e493471@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index ce0bc01b4208db288b5789e11269ee511f1a1678..5cdfcc9e3e54b9423cc22ea72d695b5a682f4e25 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1415,6 +1415,8 @@ 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);