arm64/sme: Restore SME registers on exit from suspend

The fields in SMCR_EL1 and SMPRI_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.

The vector length will be restored as part of restoring the SME state for
the next SME using task.

Fixes: a1f4ccd25cc2 ("arm64/sme: Provide Kconfig for SME")
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-v3-1-17e05e493471@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 481d94416d696a87ddaf3754c275562540bbc3a1..b67b89c54e1c83644cfdd7c63a4807dd24b8d06d 100644 (file)
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -386,6 +386,7 @@ extern void sme_alloc(struct task_struct *task, bool flush);
 extern unsigned int sme_get_vl(void);
 extern int sme_set_current_vl(unsigned long arg);
 extern int sme_get_current_vl(void);
+extern void sme_suspend_exit(void);
 
 /*
  * Return how many bytes of memory are required to store the full SME
@@ -421,6 +422,7 @@ static inline int sme_max_vl(void) { return 0; }
 static inline int sme_max_virtualisable_vl(void) { return 0; }
 static inline int sme_set_current_vl(unsigned long arg) { return -EINVAL; }
 static inline int sme_get_current_vl(void) { return -EINVAL; }
+static inline void sme_suspend_exit(void) { }
 
 static inline size_t sme_state_size(struct task_struct const *task)
 {

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 25ceaee6b025da204857af8faeadae2fa83f128c..d52592088afae3b63db4fe21f0d71afcfcfe6fe5 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1311,6 +1311,20 @@ void __init sme_setup(void)
                get_sme_default_vl());
 }
 
+void sme_suspend_exit(void)
+{
+       u64 smcr = 0;
+
+       if (!system_supports_sme())
+               return;
+
+       if (system_supports_fa64())
+               smcr |= SMCR_ELx_FA64;
+
+       write_sysreg_s(smcr, SYS_SMCR_EL1);
+       write_sysreg_s(0, SYS_SMPRI_EL1);
+}
+
 #endif /* CONFIG_ARM64_SME */
 
 static void sve_init_regs(void)

diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index eca4d043521183adc7263da95cf656323a4cc73a..eaaff94329cddb8d1fb8d1523395453f3501c9a5 100644 (file)
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -12,6 +12,7 @@
 #include <asm/daifflags.h>
 #include <asm/debug-monitors.h>
 #include <asm/exec.h>
+#include <asm/fpsimd.h>
 #include <asm/mte.h>
 #include <asm/memory.h>
 #include <asm/mmu_context.h>
@@ -80,6 +81,8 @@ void notrace __cpu_suspend_exit(void)
         */
        spectre_v4_enable_mitigation(NULL);
 
+       sme_suspend_exit();
+
        /* Restore additional feature-specific configuration */
        ptrauth_suspend_exit();
 }