3 files changed, 54 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
index 889226b4c6e1..88392272250e 100644
--- a/arch/arm64/include/asm/cpu.h
+++ b/arch/arm64/include/asm/cpu.h
@@ -41,6 +41,7 @@ struct cpuinfo_arm64 {
 	u64		reg_id_aa64mmfr2;
 	u64		reg_id_aa64pfr0;
 	u64		reg_id_aa64pfr1;
+	u64		reg_id_aa64zfr0;
 
 	u32		reg_id_dfr0;
 	u32		reg_id_isar0;
@@ -59,6 +60,9 @@ struct cpuinfo_arm64 {
 	u32		reg_mvfr0;
 	u32		reg_mvfr1;
 	u32		reg_mvfr2;
+
+	/* pseudo-ZCR for recording maximum ZCR_EL1 LEN value: */
+	u64		reg_zcr;
 };
 
 DECLARE_PER_CPU(struct cpuinfo_arm64, cpu_data);
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 4ea3441a8fa7..9b27e8c10086 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -10,7 +10,9 @@
 #define __ASM_CPUFEATURE_H
 
 #include <asm/cpucaps.h>
+#include <asm/fpsimd.h>
 #include <asm/hwcap.h>
+#include <asm/sigcontext.h>
 #include <asm/sysreg.h>
 
 /*
@@ -223,6 +225,13 @@ static inline bool id_aa64pfr0_32bit_el0(u64 pfr0)
 	return val == ID_AA64PFR0_EL0_32BIT_64BIT;
 }
 
+static inline bool id_aa64pfr0_sve(u64 pfr0)
+{
+	u32 val = cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_SVE_SHIFT);
+
+	return val > 0;
+}
+
 void __init setup_cpu_features(void);
 
 void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
@@ -267,6 +276,33 @@ static inline bool system_supports_sve(void)
 	return false;
 }
 
+/*
+ * Read the pseudo-ZCR used by cpufeatures to identify the supported SVE
+ * vector length.
+ *
+ * Use only if SVE is present.
+ * This function clobbers the SVE vector length.
+ */
+static inline u64 read_zcr_features(void)
+{
+	u64 zcr;
+	unsigned int vq_max;
+
+	/*
+	 * Set the maximum possible VL, and write zeroes to all other
+	 * bits to see if they stick.
+	 */
+	sve_kernel_enable(NULL);
+	write_sysreg_s(ZCR_ELx_LEN_MASK, SYS_ZCR_EL1);
+
+	zcr = read_sysreg_s(SYS_ZCR_EL1);
+	zcr &= ~(u64)ZCR_ELx_LEN_MASK; /* find sticky 1s outside LEN field */
+	vq_max = sve_vq_from_vl(sve_get_vl());
+	zcr |= vq_max - 1; /* set LEN field to maximum effective value */
+
+	return zcr;
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 86f550ce7b4d..d8e0dc9f65a1 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -78,6 +78,7 @@ extern void sve_save_state(void *state, u32 *pfpsr);
 extern void sve_load_state(void const *state, u32 const *pfpsr,
 			   unsigned long vq_minus_1);
 extern unsigned int sve_get_vl(void);
+extern int sve_kernel_enable(void *);
 
 extern int __ro_after_init sve_max_vl;
 
@@ -90,10 +91,23 @@ extern void fpsimd_release_task(struct task_struct *task);
 extern int sve_set_vector_length(struct task_struct *task,
 				 unsigned long vl, unsigned long flags);
 
+/*
+ * Probing and setup functions.
+ * Calls to these functions must be serialised with one another.
+ */
+extern void __init sve_init_vq_map(void);
+extern void sve_update_vq_map(void);
+extern int sve_verify_vq_map(void);
+extern void __init sve_setup(void);
+
 #else /* ! CONFIG_ARM64_SVE */
 
 static inline void sve_alloc(struct task_struct *task) { }
 static inline void fpsimd_release_task(struct task_struct *task) { }
+static inline void sve_init_vq_map(void) { }
+static inline void sve_update_vq_map(void) { }
+static inline int sve_verify_vq_map(void) { return 0; }
+static inline void sve_setup(void) { }
 
 #endif /* ! CONFIG_ARM64_SVE */