Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2136 insertions, 0 deletions

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
new file mode 100644
index 0000000000..f9b3adebcb
--- /dev/null
+++ b/arch/arm64/kernel/fpsimd.c
@@ -0,0 +1,2136 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * FP/SIMD context switching and fault handling
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Catalin Marinas <catalin.marinas@arm.com>
+ */
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/bottom_half.h>
+#include <linux/bug.h>
+#include <linux/cache.h>
+#include <linux/compat.h>
+#include <linux/compiler.h>
+#include <linux/cpu.h>
+#include <linux/cpu_pm.h>
+#include <linux/ctype.h>
+#include <linux/kernel.h>
+#include <linux/linkage.h>
+#include <linux/irqflags.h>
+#include <linux/init.h>
+#include <linux/percpu.h>
+#include <linux/prctl.h>
+#include <linux/preempt.h>
+#include <linux/ptrace.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task_stack.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/sysctl.h>
+#include <linux/swab.h>
+
+#include <asm/esr.h>
+#include <asm/exception.h>
+#include <asm/fpsimd.h>
+#include <asm/cpufeature.h>
+#include <asm/cputype.h>
+#include <asm/neon.h>
+#include <asm/processor.h>
+#include <asm/simd.h>
+#include <asm/sigcontext.h>
+#include <asm/sysreg.h>
+#include <asm/traps.h>
+#include <asm/virt.h>
+
+#define FPEXC_IOF	(1 << 0)
+#define FPEXC_DZF	(1 << 1)
+#define FPEXC_OFF	(1 << 2)
+#define FPEXC_UFF	(1 << 3)
+#define FPEXC_IXF	(1 << 4)
+#define FPEXC_IDF	(1 << 7)
+
+/*
+ * (Note: in this discussion, statements about FPSIMD apply equally to SVE.)
+ *
+ * In order to reduce the number of times the FPSIMD state is needlessly saved
+ * and restored, we need to keep track of two things:
+ * (a) for each task, we need to remember which CPU was the last one to have
+ *     the task's FPSIMD state loaded into its FPSIMD registers;
+ * (b) for each CPU, we need to remember which task's userland FPSIMD state has
+ *     been loaded into its FPSIMD registers most recently, or whether it has
+ *     been used to perform kernel mode NEON in the meantime.
+ *
+ * For (a), we add a fpsimd_cpu field to thread_struct, which gets updated to
+ * the id of the current CPU every time the state is loaded onto a CPU. For (b),
+ * we add the per-cpu variable 'fpsimd_last_state' (below), which contains the
+ * address of the userland FPSIMD state of the task that was loaded onto the CPU
+ * the most recently, or NULL if kernel mode NEON has been performed after that.
+ *
+ * With this in place, we no longer have to restore the next FPSIMD state right
+ * when switching between tasks. Instead, we can defer this check to userland
+ * resume, at which time we verify whether the CPU's fpsimd_last_state and the
+ * task's fpsimd_cpu are still mutually in sync. If this is the case, we
+ * can omit the FPSIMD restore.
+ *
+ * As an optimization, we use the thread_info flag TIF_FOREIGN_FPSTATE to
+ * indicate whether or not the userland FPSIMD state of the current task is
+ * present in the registers. The flag is set unless the FPSIMD registers of this
+ * CPU currently contain the most recent userland FPSIMD state of the current
+ * task. If the task is behaving as a VMM, then this is will be managed by
+ * KVM which will clear it to indicate that the vcpu FPSIMD state is currently
+ * loaded on the CPU, allowing the state to be saved if a FPSIMD-aware
+ * softirq kicks in. Upon vcpu_put(), KVM will save the vcpu FP state and
+ * flag the register state as invalid.
+ *
+ * In order to allow softirq handlers to use FPSIMD, kernel_neon_begin() may
+ * save the task's FPSIMD context back to task_struct from softirq context.
+ * To prevent this from racing with the manipulation of the task's FPSIMD state
+ * from task context and thereby corrupting the state, it is necessary to
+ * protect any manipulation of a task's fpsimd_state or TIF_FOREIGN_FPSTATE
+ * flag with {, __}get_cpu_fpsimd_context(). This will still allow softirqs to
+ * run but prevent them to use FPSIMD.
+ *
+ * For a certain task, the sequence may look something like this:
+ * - the task gets scheduled in; if both the task's fpsimd_cpu field
+ *   contains the id of the current CPU, and the CPU's fpsimd_last_state per-cpu
+ *   variable points to the task's fpsimd_state, the TIF_FOREIGN_FPSTATE flag is
+ *   cleared, otherwise it is set;
+ *
+ * - the task returns to userland; if TIF_FOREIGN_FPSTATE is set, the task's
+ *   userland FPSIMD state is copied from memory to the registers, the task's
+ *   fpsimd_cpu field is set to the id of the current CPU, the current
+ *   CPU's fpsimd_last_state pointer is set to this task's fpsimd_state and the
+ *   TIF_FOREIGN_FPSTATE flag is cleared;
+ *
+ * - the task executes an ordinary syscall; upon return to userland, the
+ *   TIF_FOREIGN_FPSTATE flag will still be cleared, so no FPSIMD state is
+ *   restored;
+ *
+ * - the task executes a syscall which executes some NEON instructions; this is
+ *   preceded by a call to kernel_neon_begin(), which copies the task's FPSIMD
+ *   register contents to memory, clears the fpsimd_last_state per-cpu variable
+ *   and sets the TIF_FOREIGN_FPSTATE flag;
+ *
+ * - the task gets preempted after kernel_neon_end() is called; as we have not
+ *   returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so
+ *   whatever is in the FPSIMD registers is not saved to memory, but discarded.
+ */
+
+static DEFINE_PER_CPU(struct cpu_fp_state, fpsimd_last_state);
+
+__ro_after_init struct vl_info vl_info[ARM64_VEC_MAX] = {
+#ifdef CONFIG_ARM64_SVE
+	[ARM64_VEC_SVE] = {
+		.type			= ARM64_VEC_SVE,
+		.name			= "SVE",
+		.min_vl			= SVE_VL_MIN,
+		.max_vl			= SVE_VL_MIN,
+		.max_virtualisable_vl	= SVE_VL_MIN,
+	},
+#endif
+#ifdef CONFIG_ARM64_SME
+	[ARM64_VEC_SME] = {
+		.type			= ARM64_VEC_SME,
+		.name			= "SME",
+	},
+#endif
+};
+
+static unsigned int vec_vl_inherit_flag(enum vec_type type)
+{
+	switch (type) {
+	case ARM64_VEC_SVE:
+		return TIF_SVE_VL_INHERIT;
+	case ARM64_VEC_SME:
+		return TIF_SME_VL_INHERIT;
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+}
+
+struct vl_config {
+	int __default_vl;		/* Default VL for tasks */
+};
+
+static struct vl_config vl_config[ARM64_VEC_MAX];
+
+static inline int get_default_vl(enum vec_type type)
+{
+	return READ_ONCE(vl_config[type].__default_vl);
+}
+
+#ifdef CONFIG_ARM64_SVE
+
+static inline int get_sve_default_vl(void)
+{
+	return get_default_vl(ARM64_VEC_SVE);
+}
+
+static inline void set_default_vl(enum vec_type type, int val)
+{
+	WRITE_ONCE(vl_config[type].__default_vl, val);
+}
+
+static inline void set_sve_default_vl(int val)
+{
+	set_default_vl(ARM64_VEC_SVE, val);
+}
+
+static void __percpu *efi_sve_state;
+
+#else /* ! CONFIG_ARM64_SVE */
+
+/* Dummy declaration for code that will be optimised out: */
+extern void __percpu *efi_sve_state;
+
+#endif /* ! CONFIG_ARM64_SVE */
+
+#ifdef CONFIG_ARM64_SME
+
+static int get_sme_default_vl(void)
+{
+	return get_default_vl(ARM64_VEC_SME);
+}
+
+static void set_sme_default_vl(int val)
+{
+	set_default_vl(ARM64_VEC_SME, val);
+}
+
+static void sme_free(struct task_struct *);
+
+#else
+
+static inline void sme_free(struct task_struct *t) { }
+
+#endif
+
+DEFINE_PER_CPU(bool, fpsimd_context_busy);
+EXPORT_PER_CPU_SYMBOL(fpsimd_context_busy);
+
+static void fpsimd_bind_task_to_cpu(void);
+
+static void __get_cpu_fpsimd_context(void)
+{
+	bool busy = __this_cpu_xchg(fpsimd_context_busy, true);
+
+	WARN_ON(busy);
+}
+
+/*
+ * Claim ownership of the CPU FPSIMD context for use by the calling context.
+ *
+ * The caller may freely manipulate the FPSIMD context metadata until
+ * put_cpu_fpsimd_context() is called.
+ *
+ * The double-underscore version must only be called if you know the task
+ * can't be preempted.
+ *
+ * On RT kernels local_bh_disable() is not sufficient because it only
+ * serializes soft interrupt related sections via a local lock, but stays
+ * preemptible. Disabling preemption is the right choice here as bottom
+ * half processing is always in thread context on RT kernels so it
+ * implicitly prevents bottom half processing as well.
+ */
+static void get_cpu_fpsimd_context(void)
+{
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_disable();
+	else
+		preempt_disable();
+	__get_cpu_fpsimd_context();
+}
+
+static void __put_cpu_fpsimd_context(void)
+{
+	bool busy = __this_cpu_xchg(fpsimd_context_busy, false);
+
+	WARN_ON(!busy); /* No matching get_cpu_fpsimd_context()? */
+}
+
+/*
+ * Release the CPU FPSIMD context.
+ *
+ * Must be called from a context in which get_cpu_fpsimd_context() was
+ * previously called, with no call to put_cpu_fpsimd_context() in the
+ * meantime.
+ */
+static void put_cpu_fpsimd_context(void)
+{
+	__put_cpu_fpsimd_context();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_enable();
+	else
+		preempt_enable();
+}
+
+static bool have_cpu_fpsimd_context(void)
+{
+	return !preemptible() && __this_cpu_read(fpsimd_context_busy);
+}
+
+unsigned int task_get_vl(const struct task_struct *task, enum vec_type type)
+{
+	return task->thread.vl[type];
+}
+
+void task_set_vl(struct task_struct *task, enum vec_type type,
+		 unsigned long vl)
+{
+	task->thread.vl[type] = vl;
+}
+
+unsigned int task_get_vl_onexec(const struct task_struct *task,
+				enum vec_type type)
+{
+	return task->thread.vl_onexec[type];
+}
+
+void task_set_vl_onexec(struct task_struct *task, enum vec_type type,
+			unsigned long vl)
+{
+	task->thread.vl_onexec[type] = vl;
+}
+
+/*
+ * TIF_SME controls whether a task can use SME without trapping while
+ * in userspace, when TIF_SME is set then we must have storage
+ * allocated in sve_state and sme_state to store the contents of both ZA
+ * and the SVE registers for both streaming and non-streaming modes.
+ *
+ * If both SVCR.ZA and SVCR.SM are disabled then at any point we
+ * may disable TIF_SME and reenable traps.
+ */
+
+
+/*
+ * TIF_SVE controls whether a task can use SVE without trapping while
+ * in userspace, and also (together with TIF_SME) the way a task's
+ * FPSIMD/SVE state is stored in thread_struct.
+ *
+ * The kernel uses this flag to track whether a user task is actively
+ * using SVE, and therefore whether full SVE register state needs to
+ * be tracked.  If not, the cheaper FPSIMD context handling code can
+ * be used instead of the more costly SVE equivalents.
+ *
+ *  * TIF_SVE or SVCR.SM set:
+ *
+ *    The task can execute SVE instructions while in userspace without
+ *    trapping to the kernel.
+ *
+ *    During any syscall, the kernel may optionally clear TIF_SVE and
+ *    discard the vector state except for the FPSIMD subset.
+ *
+ *  * TIF_SVE clear:
+ *
+ *    An attempt by the user task to execute an SVE instruction causes
+ *    do_sve_acc() to be called, which does some preparation and then
+ *    sets TIF_SVE.
+ *
+ * During any syscall, the kernel may optionally clear TIF_SVE and
+ * discard the vector state except for the FPSIMD subset.
+ *
+ * The data will be stored in one of two formats:
+ *
+ *  * FPSIMD only - FP_STATE_FPSIMD:
+ *
+ *    When the FPSIMD only state stored task->thread.fp_type is set to
+ *    FP_STATE_FPSIMD, the FPSIMD registers V0-V31 are encoded in
+ *    task->thread.uw.fpsimd_state; bits [max : 128] for each of Z0-Z31 are
+ *    logically zero but not stored anywhere; P0-P15 and FFR are not
+ *    stored and have unspecified values from userspace's point of
+ *    view.  For hygiene purposes, the kernel zeroes them on next use,
+ *    but userspace is discouraged from relying on this.
+ *
+ *    task->thread.sve_state does not need to be non-NULL, valid or any
+ *    particular size: it must not be dereferenced and any data stored
+ *    there should be considered stale and not referenced.
+ *
+ *  * SVE state - FP_STATE_SVE:
+ *
+ *    When the full SVE state is stored task->thread.fp_type is set to
+ *    FP_STATE_SVE and Z0-Z31 (incorporating Vn in bits[127:0] or the
+ *    corresponding Zn), P0-P15 and FFR are encoded in in
+ *    task->thread.sve_state, formatted appropriately for vector
+ *    length task->thread.sve_vl or, if SVCR.SM is set,
+ *    task->thread.sme_vl. The storage for the vector registers in
+ *    task->thread.uw.fpsimd_state should be ignored.
+ *
+ *    task->thread.sve_state must point to a valid buffer at least
+ *    sve_state_size(task) bytes in size. The data stored in
+ *    task->thread.uw.fpsimd_state.vregs should be considered stale
+ *    and not referenced.
+ *
+ *  * FPSR and FPCR are always stored in task->thread.uw.fpsimd_state
+ *    irrespective of whether TIF_SVE is clear or set, since these are
+ *    not vector length dependent.
+ */
+
+/*
+ * Update current's FPSIMD/SVE registers from thread_struct.
+ *
+ * This function should be called only when the FPSIMD/SVE state in
+ * thread_struct is known to be up to date, when preparing to enter
+ * userspace.
+ */
+static void task_fpsimd_load(void)
+{
+	bool restore_sve_regs = false;
+	bool restore_ffr;
+
+	WARN_ON(!system_supports_fpsimd());
+	WARN_ON(!have_cpu_fpsimd_context());
+
+	if (system_supports_sve() || system_supports_sme()) {
+		switch (current->thread.fp_type) {
+		case FP_STATE_FPSIMD:
+			/* Stop tracking SVE for this task until next use. */
+			if (test_and_clear_thread_flag(TIF_SVE))
+				sve_user_disable();
+			break;
+		case FP_STATE_SVE:
+			if (!thread_sm_enabled(&current->thread) &&
+			    !WARN_ON_ONCE(!test_and_set_thread_flag(TIF_SVE)))
+				sve_user_enable();
+
+			if (test_thread_flag(TIF_SVE))
+				sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1);
+
+			restore_sve_regs = true;
+			restore_ffr = true;
+			break;
+		default:
+			/*
+			 * This indicates either a bug in
+			 * fpsimd_save() or memory corruption, we
+			 * should always record an explicit format
+			 * when we save. We always at least have the
+			 * memory allocated for FPSMID registers so
+			 * try that and hope for the best.
+			 */
+			WARN_ON_ONCE(1);
+			clear_thread_flag(TIF_SVE);
+			break;
+		}
+	}
+
+	/* Restore SME, override SVE register configuration if needed */
+	if (system_supports_sme()) {
+		unsigned long sme_vl = task_get_sme_vl(current);
+
+		/* Ensure VL is set up for restoring data */
+		if (test_thread_flag(TIF_SME))
+			sme_set_vq(sve_vq_from_vl(sme_vl) - 1);
+
+		write_sysreg_s(current->thread.svcr, SYS_SVCR);
+
+		if (thread_za_enabled(&current->thread))
+			sme_load_state(current->thread.sme_state,
+				       system_supports_sme2());
+
+		if (thread_sm_enabled(&current->thread))
+			restore_ffr = system_supports_fa64();
+	}
+
+	if (restore_sve_regs) {
+		WARN_ON_ONCE(current->thread.fp_type != FP_STATE_SVE);
+		sve_load_state(sve_pffr(&current->thread),
+			       &current->thread.uw.fpsimd_state.fpsr,
+			       restore_ffr);
+	} else {
+		WARN_ON_ONCE(current->thread.fp_type != FP_STATE_FPSIMD);
+		fpsimd_load_state(&current->thread.uw.fpsimd_state);
+	}
+}
+
+/*
+ * Ensure FPSIMD/SVE storage in memory for the loaded context is up to
+ * date with respect to the CPU registers. Note carefully that the
+ * current context is the context last bound to the CPU stored in
+ * last, if KVM is involved this may be the guest VM context rather
+ * than the host thread for the VM pointed to by current. This means
+ * that we must always reference the state storage via last rather
+ * than via current, if we are saving KVM state then it will have
+ * ensured that the type of registers to save is set in last->to_save.
+ */
+static void fpsimd_save(void)
+{
+	struct cpu_fp_state const *last =
+		this_cpu_ptr(&fpsimd_last_state);
+	/* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */
+	bool save_sve_regs = false;
+	bool save_ffr;
+	unsigned int vl;
+
+	WARN_ON(!system_supports_fpsimd());
+	WARN_ON(!have_cpu_fpsimd_context());
+
+	if (test_thread_flag(TIF_FOREIGN_FPSTATE))
+		return;
+
+	/*
+	 * If a task is in a syscall the ABI allows us to only
+	 * preserve the state shared with FPSIMD so don't bother
+	 * saving the full SVE state in that case.
+	 */
+	if ((last->to_save == FP_STATE_CURRENT && test_thread_flag(TIF_SVE) &&
+	     !in_syscall(current_pt_regs())) ||
+	    last->to_save == FP_STATE_SVE) {
+		save_sve_regs = true;
+		save_ffr = true;
+		vl = last->sve_vl;
+	}
+
+	if (system_supports_sme()) {
+		u64 *svcr = last->svcr;
+
+		*svcr = read_sysreg_s(SYS_SVCR);
+
+		if (*svcr & SVCR_ZA_MASK)
+			sme_save_state(last->sme_state,
+				       system_supports_sme2());
+
+		/* If we are in streaming mode override regular SVE. */
+		if (*svcr & SVCR_SM_MASK) {
+			save_sve_regs = true;
+			save_ffr = system_supports_fa64();
+			vl = last->sme_vl;
+		}
+	}
+
+	if (IS_ENABLED(CONFIG_ARM64_SVE) && save_sve_regs) {
+		/* Get the configured VL from RDVL, will account for SM */
+		if (WARN_ON(sve_get_vl() != vl)) {
+			/*
+			 * Can't save the user regs, so current would
+			 * re-enter user with corrupt state.
+			 * There's no way to recover, so kill it:
+			 */
+			force_signal_inject(SIGKILL, SI_KERNEL, 0, 0);
+			return;
+		}
+
+		sve_save_state((char *)last->sve_state +
+					sve_ffr_offset(vl),
+			       &last->st->fpsr, save_ffr);
+		*last->fp_type = FP_STATE_SVE;
+	} else {
+		fpsimd_save_state(last->st);
+		*last->fp_type = FP_STATE_FPSIMD;
+	}
+}
+
+/*
+ * All vector length selection from userspace comes through here.
+ * We're on a slow path, so some sanity-checks are included.
+ * If things go wrong there's a bug somewhere, but try to fall back to a
+ * safe choice.
+ */
+static unsigned int find_supported_vector_length(enum vec_type type,
+						 unsigned int vl)
+{
+	struct vl_info *info = &vl_info[type];
+	int bit;
+	int max_vl = info->max_vl;
+
+	if (WARN_ON(!sve_vl_valid(vl)))
+		vl = info->min_vl;
+
+	if (WARN_ON(!sve_vl_valid(max_vl)))
+		max_vl = info->min_vl;
+
+	if (vl > max_vl)
+		vl = max_vl;
+	if (vl < info->min_vl)
+		vl = info->min_vl;
+
+	bit = find_next_bit(info->vq_map, SVE_VQ_MAX,
+			    __vq_to_bit(sve_vq_from_vl(vl)));
+	return sve_vl_from_vq(__bit_to_vq(bit));
+}
+
+#if defined(CONFIG_ARM64_SVE) && defined(CONFIG_SYSCTL)
+
+static int vec_proc_do_default_vl(struct ctl_table *table, int write,
+				  void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct vl_info *info = table->extra1;
+	enum vec_type type = info->type;
+	int ret;
+	int vl = get_default_vl(type);
+	struct ctl_table tmp_table = {
+		.data = &vl,
+		.maxlen = sizeof(vl),
+	};
+
+	ret = proc_dointvec(&tmp_table, write, buffer, lenp, ppos);
+	if (ret || !write)
+		return ret;
+
+	/* Writing -1 has the special meaning "set to max": */
+	if (vl == -1)
+		vl = info->max_vl;
+
+	if (!sve_vl_valid(vl))
+		return -EINVAL;
+
+	set_default_vl(type, find_supported_vector_length(type, vl));
+	return 0;
+}
+
+static struct ctl_table sve_default_vl_table[] = {
+	{
+		.procname	= "sve_default_vector_length",
+		.mode		= 0644,
+		.proc_handler	= vec_proc_do_default_vl,
+		.extra1		= &vl_info[ARM64_VEC_SVE],
+	},
+	{ }
+};
+
+static int __init sve_sysctl_init(void)
+{
+	if (system_supports_sve())
+		if (!register_sysctl("abi", sve_default_vl_table))
+			return -EINVAL;
+
+	return 0;
+}
+
+#else /* ! (CONFIG_ARM64_SVE && CONFIG_SYSCTL) */
+static int __init sve_sysctl_init(void) { return 0; }
+#endif /* ! (CONFIG_ARM64_SVE && CONFIG_SYSCTL) */
+
+#if defined(CONFIG_ARM64_SME) && defined(CONFIG_SYSCTL)
+static struct ctl_table sme_default_vl_table[] = {
+	{
+		.procname	= "sme_default_vector_length",
+		.mode		= 0644,
+		.proc_handler	= vec_proc_do_default_vl,
+		.extra1		= &vl_info[ARM64_VEC_SME],
+	},
+	{ }
+};
+
+static int __init sme_sysctl_init(void)
+{
+	if (system_supports_sme())
+		if (!register_sysctl("abi", sme_default_vl_table))
+			return -EINVAL;
+
+	return 0;
+}
+
+#else /* ! (CONFIG_ARM64_SME && CONFIG_SYSCTL) */
+static int __init sme_sysctl_init(void) { return 0; }
+#endif /* ! (CONFIG_ARM64_SME && CONFIG_SYSCTL) */
+
+#define ZREG(sve_state, vq, n) ((char *)(sve_state) +		\
+	(SVE_SIG_ZREG_OFFSET(vq, n) - SVE_SIG_REGS_OFFSET))
+
+#ifdef CONFIG_CPU_BIG_ENDIAN
+static __uint128_t arm64_cpu_to_le128(__uint128_t x)
+{
+	u64 a = swab64(x);
+	u64 b = swab64(x >> 64);
+
+	return ((__uint128_t)a << 64) | b;
+}
+#else
+static __uint128_t arm64_cpu_to_le128(__uint128_t x)
+{
+	return x;
+}
+#endif
+
+#define arm64_le128_to_cpu(x) arm64_cpu_to_le128(x)
+
+static void __fpsimd_to_sve(void *sst, struct user_fpsimd_state const *fst,
+			    unsigned int vq)
+{
+	unsigned int i;
+	__uint128_t *p;
+
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
+		p = (__uint128_t *)ZREG(sst, vq, i);
+		*p = arm64_cpu_to_le128(fst->vregs[i]);
+	}
+}
+
+/*
+ * Transfer the FPSIMD state in task->thread.uw.fpsimd_state to
+ * task->thread.sve_state.
+ *
+ * Task can be a non-runnable task, or current.  In the latter case,
+ * the caller must have ownership of the cpu FPSIMD context before calling
+ * this function.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.uw.fpsimd_state must be up to date before calling this
+ * function.
+ */
+static void fpsimd_to_sve(struct task_struct *task)
+{
+	unsigned int vq;
+	void *sst = task->thread.sve_state;
+	struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state;
+
+	if (!system_supports_sve() && !system_supports_sme())
+		return;
+
+	vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread));
+	__fpsimd_to_sve(sst, fst, vq);
+}
+
+/*
+ * Transfer the SVE state in task->thread.sve_state to
+ * task->thread.uw.fpsimd_state.
+ *
+ * Task can be a non-runnable task, or current.  In the latter case,
+ * the caller must have ownership of the cpu FPSIMD context before calling
+ * this function.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.sve_state must be up to date before calling this function.
+ */
+static void sve_to_fpsimd(struct task_struct *task)
+{
+	unsigned int vq, vl;
+	void const *sst = task->thread.sve_state;
+	struct user_fpsimd_state *fst = &task->thread.uw.fpsimd_state;
+	unsigned int i;
+	__uint128_t const *p;
+
+	if (!system_supports_sve() && !system_supports_sme())
+		return;
+
+	vl = thread_get_cur_vl(&task->thread);
+	vq = sve_vq_from_vl(vl);
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
+		p = (__uint128_t const *)ZREG(sst, vq, i);
+		fst->vregs[i] = arm64_le128_to_cpu(*p);
+	}
+}
+
+#ifdef CONFIG_ARM64_SVE
+/*
+ * Call __sve_free() directly only if you know task can't be scheduled
+ * or preempted.
+ */
+static void __sve_free(struct task_struct *task)
+{
+	kfree(task->thread.sve_state);
+	task->thread.sve_state = NULL;
+}
+
+static void sve_free(struct task_struct *task)
+{
+	WARN_ON(test_tsk_thread_flag(task, TIF_SVE));
+
+	__sve_free(task);
+}
+
+/*
+ * Return how many bytes of memory are required to store the full SVE
+ * state for task, given task's currently configured vector length.
+ */
+size_t sve_state_size(struct task_struct const *task)
+{
+	unsigned int vl = 0;
+
+	if (system_supports_sve())
+		vl = task_get_sve_vl(task);
+	if (system_supports_sme())
+		vl = max(vl, task_get_sme_vl(task));
+
+	return SVE_SIG_REGS_SIZE(sve_vq_from_vl(vl));
+}
+
+/*
+ * Ensure that task->thread.sve_state is allocated and sufficiently large.
+ *
+ * This function should be used only in preparation for replacing
+ * task->thread.sve_state with new data.  The memory is always zeroed
+ * here to prevent stale data from showing through: this is done in
+ * the interest of testability and predictability: except in the
+ * do_sve_acc() case, there is no ABI requirement to hide stale data
+ * written previously be task.
+ */
+void sve_alloc(struct task_struct *task, bool flush)
+{
+	if (task->thread.sve_state) {
+		if (flush)
+			memset(task->thread.sve_state, 0,
+			       sve_state_size(task));
+		return;
+	}
+
+	/* This is a small allocation (maximum ~8KB) and Should Not Fail. */
+	task->thread.sve_state =
+		kzalloc(sve_state_size(task), GFP_KERNEL);
+}
+
+
+/*
+ * Force the FPSIMD state shared with SVE to be updated in the SVE state
+ * even if the SVE state is the current active state.
+ *
+ * This should only be called by ptrace.  task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ */
+void fpsimd_force_sync_to_sve(struct task_struct *task)
+{
+	fpsimd_to_sve(task);
+}
+
+/*
+ * Ensure that task->thread.sve_state is up to date with respect to
+ * the user task, irrespective of when SVE is in use or not.
+ *
+ * This should only be called by ptrace.  task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ */
+void fpsimd_sync_to_sve(struct task_struct *task)
+{
+	if (!test_tsk_thread_flag(task, TIF_SVE) &&
+	    !thread_sm_enabled(&task->thread))
+		fpsimd_to_sve(task);
+}
+
+/*
+ * Ensure that task->thread.uw.fpsimd_state is up to date with respect to
+ * the user task, irrespective of whether SVE is in use or not.
+ *
+ * This should only be called by ptrace.  task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ */
+void sve_sync_to_fpsimd(struct task_struct *task)
+{
+	if (task->thread.fp_type == FP_STATE_SVE)
+		sve_to_fpsimd(task);
+}
+
+/*
+ * Ensure that task->thread.sve_state is up to date with respect to
+ * the task->thread.uw.fpsimd_state.
+ *
+ * This should only be called by ptrace to merge new FPSIMD register
+ * values into a task for which SVE is currently active.
+ * task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.uw.fpsimd_state must already have been initialised with
+ * the new FPSIMD register values to be merged in.
+ */
+void sve_sync_from_fpsimd_zeropad(struct task_struct *task)
+{
+	unsigned int vq;
+	void *sst = task->thread.sve_state;
+	struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state;
+
+	if (!test_tsk_thread_flag(task, TIF_SVE) &&
+	    !thread_sm_enabled(&task->thread))
+		return;
+
+	vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread));
+
+	memset(sst, 0, SVE_SIG_REGS_SIZE(vq));
+	__fpsimd_to_sve(sst, fst, vq);
+}
+
+int vec_set_vector_length(struct task_struct *task, enum vec_type type,
+			  unsigned long vl, unsigned long flags)
+{
+	bool free_sme = false;
+
+	if (flags & ~(unsigned long)(PR_SVE_VL_INHERIT |
+				     PR_SVE_SET_VL_ONEXEC))
+		return -EINVAL;
+
+	if (!sve_vl_valid(vl))
+		return -EINVAL;
+
+	/*
+	 * Clamp to the maximum vector length that VL-agnostic code
+	 * can work with.  A flag may be assigned in the future to
+	 * allow setting of larger vector lengths without confusing
+	 * older software.
+	 */
+	if (vl > VL_ARCH_MAX)
+		vl = VL_ARCH_MAX;
+
+	vl = find_supported_vector_length(type, vl);
+
+	if (flags & (PR_SVE_VL_INHERIT |
+		     PR_SVE_SET_VL_ONEXEC))
+		task_set_vl_onexec(task, type, vl);
+	else
+		/* Reset VL to system default on next exec: */
+		task_set_vl_onexec(task, type, 0);
+
+	/* Only actually set the VL if not deferred: */
+	if (flags & PR_SVE_SET_VL_ONEXEC)
+		goto out;
+
+	if (vl == task_get_vl(task, type))
+		goto out;
+
+	/*
+	 * To ensure the FPSIMD bits of the SVE vector registers are preserved,
+	 * write any live register state back to task_struct, and convert to a
+	 * regular FPSIMD thread.
+	 */
+	if (task == current) {
+		get_cpu_fpsimd_context();
+
+		fpsimd_save();
+	}
+
+	fpsimd_flush_task_state(task);
+	if (test_and_clear_tsk_thread_flag(task, TIF_SVE) ||
+	    thread_sm_enabled(&task->thread)) {
+		sve_to_fpsimd(task);
+		task->thread.fp_type = FP_STATE_FPSIMD;
+	}
+
+	if (system_supports_sme()) {
+		if (type == ARM64_VEC_SME ||
+		    !(task->thread.svcr & (SVCR_SM_MASK | SVCR_ZA_MASK))) {
+			/*
+			 * We are changing the SME VL or weren't using
+			 * SME anyway, discard the state and force a
+			 * reallocation.
+			 */
+			task->thread.svcr &= ~(SVCR_SM_MASK |
+					       SVCR_ZA_MASK);
+			clear_tsk_thread_flag(task, TIF_SME);
+			free_sme = true;
+		}
+	}
+
+	if (task == current)
+		put_cpu_fpsimd_context();
+
+	task_set_vl(task, type, vl);
+
+	/*
+	 * Free the changed states if they are not in use, SME will be
+	 * reallocated to the correct size on next use and we just
+	 * allocate SVE now in case it is needed for use in streaming
+	 * mode.
+	 */
+	if (system_supports_sve()) {
+		sve_free(task);
+		sve_alloc(task, true);
+	}
+
+	if (free_sme)
+		sme_free(task);
+
+out:
+	update_tsk_thread_flag(task, vec_vl_inherit_flag(type),
+			       flags & PR_SVE_VL_INHERIT);
+
+	return 0;
+}
+
+/*
+ * Encode the current vector length and flags for return.
+ * This is only required for prctl(): ptrace has separate fields.
+ * SVE and SME use the same bits for _ONEXEC and _INHERIT.
+ *
+ * flags are as for vec_set_vector_length().
+ */
+static int vec_prctl_status(enum vec_type type, unsigned long flags)
+{
+	int ret;
+
+	if (flags & PR_SVE_SET_VL_ONEXEC)
+		ret = task_get_vl_onexec(current, type);
+	else
+		ret = task_get_vl(current, type);
+
+	if (test_thread_flag(vec_vl_inherit_flag(type)))
+		ret |= PR_SVE_VL_INHERIT;
+
+	return ret;
+}
+
+/* PR_SVE_SET_VL */
+int sve_set_current_vl(unsigned long arg)
+{
+	unsigned long vl, flags;
+	int ret;
+
+	vl = arg & PR_SVE_VL_LEN_MASK;
+	flags = arg & ~vl;
+
+	if (!system_supports_sve() || is_compat_task())
+		return -EINVAL;
+
+	ret = vec_set_vector_length(current, ARM64_VEC_SVE, vl, flags);
+	if (ret)
+		return ret;
+
+	return vec_prctl_status(ARM64_VEC_SVE, flags);
+}
+
+/* PR_SVE_GET_VL */
+int sve_get_current_vl(void)
+{
+	if (!system_supports_sve() || is_compat_task())
+		return -EINVAL;
+
+	return vec_prctl_status(ARM64_VEC_SVE, 0);
+}
+
+#ifdef CONFIG_ARM64_SME
+/* PR_SME_SET_VL */
+int sme_set_current_vl(unsigned long arg)
+{
+	unsigned long vl, flags;
+	int ret;
+
+	vl = arg & PR_SME_VL_LEN_MASK;
+	flags = arg & ~vl;
+
+	if (!system_supports_sme() || is_compat_task())
+		return -EINVAL;
+
+	ret = vec_set_vector_length(current, ARM64_VEC_SME, vl, flags);
+	if (ret)
+		return ret;
+
+	return vec_prctl_status(ARM64_VEC_SME, flags);
+}
+
+/* PR_SME_GET_VL */
+int sme_get_current_vl(void)
+{
+	if (!system_supports_sme() || is_compat_task())
+		return -EINVAL;
+
+	return vec_prctl_status(ARM64_VEC_SME, 0);
+}
+#endif /* CONFIG_ARM64_SME */
+
+static void vec_probe_vqs(struct vl_info *info,
+			  DECLARE_BITMAP(map, SVE_VQ_MAX))
+{
+	unsigned int vq, vl;
+
+	bitmap_zero(map, SVE_VQ_MAX);
+
+	for (vq = SVE_VQ_MAX; vq >= SVE_VQ_MIN; --vq) {
+		write_vl(info->type, vq - 1); /* self-syncing */
+
+		switch (info->type) {
+		case ARM64_VEC_SVE:
+			vl = sve_get_vl();
+			break;
+		case ARM64_VEC_SME:
+			vl = sme_get_vl();
+			break;
+		default:
+			vl = 0;
+			break;
+		}
+
+		/* Minimum VL identified? */
+		if (sve_vq_from_vl(vl) > vq)
+			break;
+
+		vq = sve_vq_from_vl(vl); /* skip intervening lengths */
+		set_bit(__vq_to_bit(vq), map);
+	}
+}
+
+/*
+ * Initialise the set of known supported VQs for the boot CPU.
+ * This is called during kernel boot, before secondary CPUs are brought up.
+ */
+void __init vec_init_vq_map(enum vec_type type)
+{
+	struct vl_info *info = &vl_info[type];
+	vec_probe_vqs(info, info->vq_map);
+	bitmap_copy(info->vq_partial_map, info->vq_map, SVE_VQ_MAX);
+}
+
+/*
+ * If we haven't committed to the set of supported VQs yet, filter out
+ * those not supported by the current CPU.
+ * This function is called during the bring-up of early secondary CPUs only.
+ */
+void vec_update_vq_map(enum vec_type type)
+{
+	struct vl_info *info = &vl_info[type];
+	DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
+
+	vec_probe_vqs(info, tmp_map);
+	bitmap_and(info->vq_map, info->vq_map, tmp_map, SVE_VQ_MAX);
+	bitmap_or(info->vq_partial_map, info->vq_partial_map, tmp_map,
+		  SVE_VQ_MAX);
+}
+
+/*
+ * Check whether the current CPU supports all VQs in the committed set.
+ * This function is called during the bring-up of late secondary CPUs only.
+ */
+int vec_verify_vq_map(enum vec_type type)
+{
+	struct vl_info *info = &vl_info[type];
+	DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
+	unsigned long b;
+
+	vec_probe_vqs(info, tmp_map);
+
+	bitmap_complement(tmp_map, tmp_map, SVE_VQ_MAX);
+	if (bitmap_intersects(tmp_map, info->vq_map, SVE_VQ_MAX)) {
+		pr_warn("%s: cpu%d: Required vector length(s) missing\n",
+			info->name, smp_processor_id());
+		return -EINVAL;
+	}
+
+	if (!IS_ENABLED(CONFIG_KVM) || !is_hyp_mode_available())
+		return 0;
+
+	/*
+	 * For KVM, it is necessary to ensure that this CPU doesn't
+	 * support any vector length that guests may have probed as
+	 * unsupported.
+	 */
+
+	/* Recover the set of supported VQs: */
+	bitmap_complement(tmp_map, tmp_map, SVE_VQ_MAX);
+	/* Find VQs supported that are not globally supported: */
+	bitmap_andnot(tmp_map, tmp_map, info->vq_map, SVE_VQ_MAX);
+
+	/* Find the lowest such VQ, if any: */
+	b = find_last_bit(tmp_map, SVE_VQ_MAX);
+	if (b >= SVE_VQ_MAX)
+		return 0; /* no mismatches */
+
+	/*
+	 * Mismatches above sve_max_virtualisable_vl are fine, since
+	 * no guest is allowed to configure ZCR_EL2.LEN to exceed this:
+	 */
+	if (sve_vl_from_vq(__bit_to_vq(b)) <= info->max_virtualisable_vl) {
+		pr_warn("%s: cpu%d: Unsupported vector length(s) present\n",
+			info->name, smp_processor_id());
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void __init sve_efi_setup(void)
+{
+	int max_vl = 0;
+	int i;
+
+	if (!IS_ENABLED(CONFIG_EFI))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(vl_info); i++)
+		max_vl = max(vl_info[i].max_vl, max_vl);
+
+	/*
+	 * alloc_percpu() warns and prints a backtrace if this goes wrong.
+	 * This is evidence of a crippled system and we are returning void,
+	 * so no attempt is made to handle this situation here.
+	 */
+	if (!sve_vl_valid(max_vl))
+		goto fail;
+
+	efi_sve_state = __alloc_percpu(
+		SVE_SIG_REGS_SIZE(sve_vq_from_vl(max_vl)), SVE_VQ_BYTES);
+	if (!efi_sve_state)
+		goto fail;
+
+	return;
+
+fail:
+	panic("Cannot allocate percpu memory for EFI SVE save/restore");
+}
+
+/*
+ * Enable SVE for EL1.
+ * Intended for use by the cpufeatures code during CPU boot.
+ */
+void sve_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
+{
+	write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1);
+	isb();
+}
+
+/*
+ * 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.
+ */
+u64 read_zcr_features(void)
+{
+	/*
+	 * 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);
+
+	/* Return LEN value that would be written to get the maximum VL */
+	return sve_vq_from_vl(sve_get_vl()) - 1;
+}
+
+void __init sve_setup(void)
+{
+	struct vl_info *info = &vl_info[ARM64_VEC_SVE];
+	u64 zcr;
+	DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
+	unsigned long b;
+
+	if (!system_supports_sve())
+		return;
+
+	/*
+	 * The SVE architecture mandates support for 128-bit vectors,
+	 * so sve_vq_map must have at least SVE_VQ_MIN set.
+	 * If something went wrong, at least try to patch it up:
+	 */
+	if (WARN_ON(!test_bit(__vq_to_bit(SVE_VQ_MIN), info->vq_map)))
+		set_bit(__vq_to_bit(SVE_VQ_MIN), info->vq_map);
+
+	zcr = read_sanitised_ftr_reg(SYS_ZCR_EL1);
+	info->max_vl = sve_vl_from_vq((zcr & ZCR_ELx_LEN_MASK) + 1);
+
+	/*
+	 * Sanity-check that the max VL we determined through CPU features
+	 * corresponds properly to sve_vq_map.  If not, do our best:
+	 */
+	if (WARN_ON(info->max_vl != find_supported_vector_length(ARM64_VEC_SVE,
+								 info->max_vl)))
+		info->max_vl = find_supported_vector_length(ARM64_VEC_SVE,
+							    info->max_vl);
+
+	/*
+	 * For the default VL, pick the maximum supported value <= 64.
+	 * VL == 64 is guaranteed not to grow the signal frame.
+	 */
+	set_sve_default_vl(find_supported_vector_length(ARM64_VEC_SVE, 64));
+
+	bitmap_andnot(tmp_map, info->vq_partial_map, info->vq_map,
+		      SVE_VQ_MAX);
+
+	b = find_last_bit(tmp_map, SVE_VQ_MAX);
+	if (b >= SVE_VQ_MAX)
+		/* No non-virtualisable VLs found */
+		info->max_virtualisable_vl = SVE_VQ_MAX;
+	else if (WARN_ON(b == SVE_VQ_MAX - 1))
+		/* No virtualisable VLs?  This is architecturally forbidden. */
+		info->max_virtualisable_vl = SVE_VQ_MIN;
+	else /* b + 1 < SVE_VQ_MAX */
+		info->max_virtualisable_vl = sve_vl_from_vq(__bit_to_vq(b + 1));
+
+	if (info->max_virtualisable_vl > info->max_vl)
+		info->max_virtualisable_vl = info->max_vl;
+
+	pr_info("%s: maximum available vector length %u bytes per vector\n",
+		info->name, info->max_vl);
+	pr_info("%s: default vector length %u bytes per vector\n",
+		info->name, get_sve_default_vl());
+
+	/* KVM decides whether to support mismatched systems. Just warn here: */
+	if (sve_max_virtualisable_vl() < sve_max_vl())
+		pr_warn("%s: unvirtualisable vector lengths present\n",
+			info->name);
+
+	sve_efi_setup();
+}
+
+/*
+ * Called from the put_task_struct() path, which cannot get here
+ * unless dead_task is really dead and not schedulable.
+ */
+void fpsimd_release_task(struct task_struct *dead_task)
+{
+	__sve_free(dead_task);
+	sme_free(dead_task);
+}
+
+#endif /* CONFIG_ARM64_SVE */
+
+#ifdef CONFIG_ARM64_SME
+
+/*
+ * Ensure that task->thread.sme_state is allocated and sufficiently large.
+ *
+ * This function should be used only in preparation for replacing
+ * task->thread.sme_state with new data.  The memory is always zeroed
+ * here to prevent stale data from showing through: this is done in
+ * the interest of testability and predictability, the architecture
+ * guarantees that when ZA is enabled it will be zeroed.
+ */
+void sme_alloc(struct task_struct *task, bool flush)
+{
+	if (task->thread.sme_state) {
+		if (flush)
+			memset(task->thread.sme_state, 0,
+			       sme_state_size(task));
+		return;
+	}
+
+	/* This could potentially be up to 64K. */
+	task->thread.sme_state =
+		kzalloc(sme_state_size(task), GFP_KERNEL);
+}
+
+static void sme_free(struct task_struct *task)
+{
+	kfree(task->thread.sme_state);
+	task->thread.sme_state = NULL;
+}
+
+void sme_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
+{
+	/* Set priority for all PEs to architecturally defined minimum */
+	write_sysreg_s(read_sysreg_s(SYS_SMPRI_EL1) & ~SMPRI_EL1_PRIORITY_MASK,
+		       SYS_SMPRI_EL1);
+
+	/* Allow SME in kernel */
+	write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_SMEN_EL1EN, CPACR_EL1);
+	isb();
+
+	/* Allow EL0 to access TPIDR2 */
+	write_sysreg(read_sysreg(SCTLR_EL1) | SCTLR_ELx_ENTP2, SCTLR_EL1);
+	isb();
+}
+
+/*
+ * This must be called after sme_kernel_enable(), we rely on the
+ * feature table being sorted to ensure this.
+ */
+void sme2_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
+{
+	/* Allow use of ZT0 */
+	write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_EZT0_MASK,
+		       SYS_SMCR_EL1);
+}
+
+/*
+ * This must be called after sme_kernel_enable(), we rely on the
+ * feature table being sorted to ensure this.
+ */
+void fa64_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
+{
+	/* Allow use of FA64 */
+	write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_FA64_MASK,
+		       SYS_SMCR_EL1);
+}
+
+/*
+ * Read the pseudo-SMCR used by cpufeatures to identify the supported
+ * vector length.
+ *
+ * Use only if SME is present.
+ * This function clobbers the SME vector length.
+ */
+u64 read_smcr_features(void)
+{
+	sme_kernel_enable(NULL);
+
+	/*
+	 * Set the maximum possible VL.
+	 */
+	write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_LEN_MASK,
+		       SYS_SMCR_EL1);
+
+	/* Return LEN value that would be written to get the maximum VL */
+	return sve_vq_from_vl(sme_get_vl()) - 1;
+}
+
+void __init sme_setup(void)
+{
+	struct vl_info *info = &vl_info[ARM64_VEC_SME];
+	u64 smcr;
+	int min_bit;
+
+	if (!system_supports_sme())
+		return;
+
+	/*
+	 * SME doesn't require any particular vector length be
+	 * supported but it does require at least one.  We should have
+	 * disabled the feature entirely while bringing up CPUs but
+	 * let's double check here.
+	 */
+	WARN_ON(bitmap_empty(info->vq_map, SVE_VQ_MAX));
+
+	min_bit = find_last_bit(info->vq_map, SVE_VQ_MAX);
+	info->min_vl = sve_vl_from_vq(__bit_to_vq(min_bit));
+
+	smcr = read_sanitised_ftr_reg(SYS_SMCR_EL1);
+	info->max_vl = sve_vl_from_vq((smcr & SMCR_ELx_LEN_MASK) + 1);
+
+	/*
+	 * Sanity-check that the max VL we determined through CPU features
+	 * corresponds properly to sme_vq_map.  If not, do our best:
+	 */
+	if (WARN_ON(info->max_vl != find_supported_vector_length(ARM64_VEC_SME,
+								 info->max_vl)))
+		info->max_vl = find_supported_vector_length(ARM64_VEC_SME,
+							    info->max_vl);
+
+	WARN_ON(info->min_vl > info->max_vl);
+
+	/*
+	 * For the default VL, pick the maximum supported value <= 32
+	 * (256 bits) if there is one since this is guaranteed not to
+	 * grow the signal frame when in streaming mode, otherwise the
+	 * minimum available VL will be used.
+	 */
+	set_sme_default_vl(find_supported_vector_length(ARM64_VEC_SME, 32));
+
+	pr_info("SME: minimum available vector length %u bytes per vector\n",
+		info->min_vl);
+	pr_info("SME: maximum available vector length %u bytes per vector\n",
+		info->max_vl);
+	pr_info("SME: default vector length %u bytes per vector\n",
+		get_sme_default_vl());
+}
+
+#endif /* CONFIG_ARM64_SME */
+
+static void sve_init_regs(void)
+{
+	/*
+	 * Convert the FPSIMD state to SVE, zeroing all the state that
+	 * is not shared with FPSIMD. If (as is likely) the current
+	 * state is live in the registers then do this there and
+	 * update our metadata for the current task including
+	 * disabling the trap, otherwise update our in-memory copy.
+	 * We are guaranteed to not be in streaming mode, we can only
+	 * take a SVE trap when not in streaming mode and we can't be
+	 * in streaming mode when taking a SME trap.
+	 */
+	if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
+		unsigned long vq_minus_one =
+			sve_vq_from_vl(task_get_sve_vl(current)) - 1;
+		sve_set_vq(vq_minus_one);
+		sve_flush_live(true, vq_minus_one);
+		fpsimd_bind_task_to_cpu();
+	} else {
+		fpsimd_to_sve(current);
+		current->thread.fp_type = FP_STATE_SVE;
+	}
+}
+
+/*
+ * Trapped SVE access
+ *
+ * Storage is allocated for the full SVE state, the current FPSIMD
+ * register contents are migrated across, and the access trap is
+ * disabled.
+ *
+ * TIF_SVE should be clear on entry: otherwise, fpsimd_restore_current_state()
+ * would have disabled the SVE access trap for userspace during
+ * ret_to_user, making an SVE access trap impossible in that case.
+ */
+void do_sve_acc(unsigned long esr, struct pt_regs *regs)
+{
+	/* Even if we chose not to use SVE, the hardware could still trap: */
+	if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) {
+		force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
+		return;
+	}
+
+	sve_alloc(current, true);
+	if (!current->thread.sve_state) {
+		force_sig(SIGKILL);
+		return;
+	}
+
+	get_cpu_fpsimd_context();
+
+	if (test_and_set_thread_flag(TIF_SVE))
+		WARN_ON(1); /* SVE access shouldn't have trapped */
+
+	/*
+	 * Even if the task can have used streaming mode we can only
+	 * generate SVE access traps in normal SVE mode and
+	 * transitioning out of streaming mode may discard any
+	 * streaming mode state.  Always clear the high bits to avoid
+	 * any potential errors tracking what is properly initialised.
+	 */
+	sve_init_regs();
+
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Trapped SME access
+ *
+ * Storage is allocated for the full SVE and SME state, the current
+ * FPSIMD register contents are migrated to SVE if SVE is not already
+ * active, and the access trap is disabled.
+ *
+ * TIF_SME should be clear on entry: otherwise, fpsimd_restore_current_state()
+ * would have disabled the SME access trap for userspace during
+ * ret_to_user, making an SME access trap impossible in that case.
+ */
+void do_sme_acc(unsigned long esr, struct pt_regs *regs)
+{
+	/* Even if we chose not to use SME, the hardware could still trap: */
+	if (unlikely(!system_supports_sme()) || WARN_ON(is_compat_task())) {
+		force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
+		return;
+	}
+
+	/*
+	 * If this not a trap due to SME being disabled then something
+	 * is being used in the wrong mode, report as SIGILL.
+	 */
+	if (ESR_ELx_ISS(esr) != ESR_ELx_SME_ISS_SME_DISABLED) {
+		force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
+		return;
+	}
+
+	sve_alloc(current, false);
+	sme_alloc(current, true);
+	if (!current->thread.sve_state || !current->thread.sme_state) {
+		force_sig(SIGKILL);
+		return;
+	}
+
+	get_cpu_fpsimd_context();
+
+	/* With TIF_SME userspace shouldn't generate any traps */
+	if (test_and_set_thread_flag(TIF_SME))
+		WARN_ON(1);
+
+	if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
+		unsigned long vq_minus_one =
+			sve_vq_from_vl(task_get_sme_vl(current)) - 1;
+		sme_set_vq(vq_minus_one);
+
+		fpsimd_bind_task_to_cpu();
+	}
+
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Trapped FP/ASIMD access.
+ */
+void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs)
+{
+	/* TODO: implement lazy context saving/restoring */
+	WARN_ON(1);
+}
+
+/*
+ * Raise a SIGFPE for the current process.
+ */
+void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs)
+{
+	unsigned int si_code = FPE_FLTUNK;
+
+	if (esr & ESR_ELx_FP_EXC_TFV) {
+		if (esr & FPEXC_IOF)
+			si_code = FPE_FLTINV;
+		else if (esr & FPEXC_DZF)
+			si_code = FPE_FLTDIV;
+		else if (esr & FPEXC_OFF)
+			si_code = FPE_FLTOVF;
+		else if (esr & FPEXC_UFF)
+			si_code = FPE_FLTUND;
+		else if (esr & FPEXC_IXF)
+			si_code = FPE_FLTRES;
+	}
+
+	send_sig_fault(SIGFPE, si_code,
+		       (void __user *)instruction_pointer(regs),
+		       current);
+}
+
+void fpsimd_thread_switch(struct task_struct *next)
+{
+	bool wrong_task, wrong_cpu;
+
+	if (!system_supports_fpsimd())
+		return;
+
+	__get_cpu_fpsimd_context();
+
+	/* Save unsaved fpsimd state, if any: */
+	fpsimd_save();
+
+	/*
+	 * Fix up TIF_FOREIGN_FPSTATE to correctly describe next's
+	 * state.  For kernel threads, FPSIMD registers are never loaded
+	 * and wrong_task and wrong_cpu will always be true.
+	 */
+	wrong_task = __this_cpu_read(fpsimd_last_state.st) !=
+					&next->thread.uw.fpsimd_state;
+	wrong_cpu = next->thread.fpsimd_cpu != smp_processor_id();
+
+	update_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE,
+			       wrong_task || wrong_cpu);
+
+	__put_cpu_fpsimd_context();
+}
+
+static void fpsimd_flush_thread_vl(enum vec_type type)
+{
+	int vl, supported_vl;
+
+	/*
+	 * Reset the task vector length as required.  This is where we
+	 * ensure that all user tasks have a valid vector length
+	 * configured: no kernel task can become a user task without
+	 * an exec and hence a call to this function.  By the time the
+	 * first call to this function is made, all early hardware
+	 * probing is complete, so __sve_default_vl should be valid.
+	 * If a bug causes this to go wrong, we make some noise and
+	 * try to fudge thread.sve_vl to a safe value here.
+	 */
+	vl = task_get_vl_onexec(current, type);
+	if (!vl)
+		vl = get_default_vl(type);
+
+	if (WARN_ON(!sve_vl_valid(vl)))
+		vl = vl_info[type].min_vl;
+
+	supported_vl = find_supported_vector_length(type, vl);
+	if (WARN_ON(supported_vl != vl))
+		vl = supported_vl;
+
+	task_set_vl(current, type, vl);
+
+	/*
+	 * If the task is not set to inherit, ensure that the vector
+	 * length will be reset by a subsequent exec:
+	 */
+	if (!test_thread_flag(vec_vl_inherit_flag(type)))
+		task_set_vl_onexec(current, type, 0);
+}
+
+void fpsimd_flush_thread(void)
+{
+	void *sve_state = NULL;
+	void *sme_state = NULL;
+
+	if (!system_supports_fpsimd())
+		return;
+
+	get_cpu_fpsimd_context();
+
+	fpsimd_flush_task_state(current);
+	memset(&current->thread.uw.fpsimd_state, 0,
+	       sizeof(current->thread.uw.fpsimd_state));
+
+	if (system_supports_sve()) {
+		clear_thread_flag(TIF_SVE);
+
+		/* Defer kfree() while in atomic context */
+		sve_state = current->thread.sve_state;
+		current->thread.sve_state = NULL;
+
+		fpsimd_flush_thread_vl(ARM64_VEC_SVE);
+	}
+
+	if (system_supports_sme()) {
+		clear_thread_flag(TIF_SME);
+
+		/* Defer kfree() while in atomic context */
+		sme_state = current->thread.sme_state;
+		current->thread.sme_state = NULL;
+
+		fpsimd_flush_thread_vl(ARM64_VEC_SME);
+		current->thread.svcr = 0;
+	}
+
+	current->thread.fp_type = FP_STATE_FPSIMD;
+
+	put_cpu_fpsimd_context();
+	kfree(sve_state);
+	kfree(sme_state);
+}
+
+/*
+ * Save the userland FPSIMD state of 'current' to memory, but only if the state
+ * currently held in the registers does in fact belong to 'current'
+ */
+void fpsimd_preserve_current_state(void)
+{
+	if (!system_supports_fpsimd())
+		return;
+
+	get_cpu_fpsimd_context();
+	fpsimd_save();
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Like fpsimd_preserve_current_state(), but ensure that
+ * current->thread.uw.fpsimd_state is updated so that it can be copied to
+ * the signal frame.
+ */
+void fpsimd_signal_preserve_current_state(void)
+{
+	fpsimd_preserve_current_state();
+	if (test_thread_flag(TIF_SVE))
+		sve_to_fpsimd(current);
+}
+
+/*
+ * Called by KVM when entering the guest.
+ */
+void fpsimd_kvm_prepare(void)
+{
+	if (!system_supports_sve())
+		return;
+
+	/*
+	 * KVM does not save host SVE state since we can only enter
+	 * the guest from a syscall so the ABI means that only the
+	 * non-saved SVE state needs to be saved.  If we have left
+	 * SVE enabled for performance reasons then update the task
+	 * state to be FPSIMD only.
+	 */
+	get_cpu_fpsimd_context();
+
+	if (test_and_clear_thread_flag(TIF_SVE)) {
+		sve_to_fpsimd(current);
+		current->thread.fp_type = FP_STATE_FPSIMD;
+	}
+
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Associate current's FPSIMD context with this cpu
+ * The caller must have ownership of the cpu FPSIMD context before calling
+ * this function.
+ */
+static void fpsimd_bind_task_to_cpu(void)
+{
+	struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);
+
+	WARN_ON(!system_supports_fpsimd());
+	last->st = &current->thread.uw.fpsimd_state;
+	last->sve_state = current->thread.sve_state;
+	last->sme_state = current->thread.sme_state;
+	last->sve_vl = task_get_sve_vl(current);
+	last->sme_vl = task_get_sme_vl(current);
+	last->svcr = &current->thread.svcr;
+	last->fp_type = &current->thread.fp_type;
+	last->to_save = FP_STATE_CURRENT;
+	current->thread.fpsimd_cpu = smp_processor_id();
+
+	/*
+	 * Toggle SVE and SME trapping for userspace if needed, these
+	 * are serialsied by ret_to_user().
+	 */
+	if (system_supports_sme()) {
+		if (test_thread_flag(TIF_SME))
+			sme_user_enable();
+		else
+			sme_user_disable();
+	}
+
+	if (system_supports_sve()) {
+		if (test_thread_flag(TIF_SVE))
+			sve_user_enable();
+		else
+			sve_user_disable();
+	}
+}
+
+void fpsimd_bind_state_to_cpu(struct cpu_fp_state *state)
+{
+	struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);
+
+	WARN_ON(!system_supports_fpsimd());
+	WARN_ON(!in_softirq() && !irqs_disabled());
+
+	*last = *state;
+}
+
+/*
+ * Load the userland FPSIMD state of 'current' from memory, but only if the
+ * FPSIMD state already held in the registers is /not/ the most recent FPSIMD
+ * state of 'current'.  This is called when we are preparing to return to
+ * userspace to ensure that userspace sees a good register state.
+ */
+void fpsimd_restore_current_state(void)
+{
+	/*
+	 * For the tasks that were created before we detected the absence of
+	 * FP/SIMD, the TIF_FOREIGN_FPSTATE could be set via fpsimd_thread_switch(),
+	 * e.g, init. This could be then inherited by the children processes.
+	 * If we later detect that the system doesn't support FP/SIMD,
+	 * we must clear the flag for  all the tasks to indicate that the
+	 * FPSTATE is clean (as we can't have one) to avoid looping for ever in
+	 * do_notify_resume().
+	 */
+	if (!system_supports_fpsimd()) {
+		clear_thread_flag(TIF_FOREIGN_FPSTATE);
+		return;
+	}
+
+	get_cpu_fpsimd_context();
+
+	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
+		task_fpsimd_load();
+		fpsimd_bind_task_to_cpu();
+	}
+
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Load an updated userland FPSIMD state for 'current' from memory and set the
+ * flag that indicates that the FPSIMD register contents are the most recent
+ * FPSIMD state of 'current'. This is used by the signal code to restore the
+ * register state when returning from a signal handler in FPSIMD only cases,
+ * any SVE context will be discarded.
+ */
+void fpsimd_update_current_state(struct user_fpsimd_state const *state)
+{
+	if (WARN_ON(!system_supports_fpsimd()))
+		return;
+
+	get_cpu_fpsimd_context();
+
+	current->thread.uw.fpsimd_state = *state;
+	if (test_thread_flag(TIF_SVE))
+		fpsimd_to_sve(current);
+
+	task_fpsimd_load();
+	fpsimd_bind_task_to_cpu();
+
+	clear_thread_flag(TIF_FOREIGN_FPSTATE);
+
+	put_cpu_fpsimd_context();
+}
+
+/*
+ * Invalidate live CPU copies of task t's FPSIMD state
+ *
+ * This function may be called with preemption enabled.  The barrier()
+ * ensures that the assignment to fpsimd_cpu is visible to any
+ * preemption/softirq that could race with set_tsk_thread_flag(), so
+ * that TIF_FOREIGN_FPSTATE cannot be spuriously re-cleared.
+ *
+ * The final barrier ensures that TIF_FOREIGN_FPSTATE is seen set by any
+ * subsequent code.
+ */
+void fpsimd_flush_task_state(struct task_struct *t)
+{
+	t->thread.fpsimd_cpu = NR_CPUS;
+	/*
+	 * If we don't support fpsimd, bail out after we have
+	 * reset the fpsimd_cpu for this task and clear the
+	 * FPSTATE.
+	 */
+	if (!system_supports_fpsimd())
+		return;
+	barrier();
+	set_tsk_thread_flag(t, TIF_FOREIGN_FPSTATE);
+
+	barrier();
+}
+
+/*
+ * Invalidate any task's FPSIMD state that is present on this cpu.
+ * The FPSIMD context should be acquired with get_cpu_fpsimd_context()
+ * before calling this function.
+ */
+static void fpsimd_flush_cpu_state(void)
+{
+	WARN_ON(!system_supports_fpsimd());
+	__this_cpu_write(fpsimd_last_state.st, NULL);
+
+	/*
+	 * Leaving streaming mode enabled will cause issues for any kernel
+	 * NEON and leaving streaming mode or ZA enabled may increase power
+	 * consumption.
+	 */
+	if (system_supports_sme())
+		sme_smstop();
+
+	set_thread_flag(TIF_FOREIGN_FPSTATE);
+}
+
+/*
+ * Save the FPSIMD state to memory and invalidate cpu view.
+ * This function must be called with preemption disabled.
+ */
+void fpsimd_save_and_flush_cpu_state(void)
+{
+	if (!system_supports_fpsimd())
+		return;
+	WARN_ON(preemptible());
+	__get_cpu_fpsimd_context();
+	fpsimd_save();
+	fpsimd_flush_cpu_state();
+	__put_cpu_fpsimd_context();
+}
+
+#ifdef CONFIG_KERNEL_MODE_NEON
+
+/*
+ * Kernel-side NEON support functions
+ */
+
+/*
+ * kernel_neon_begin(): obtain the CPU FPSIMD registers for use by the calling
+ * context
+ *
+ * Must not be called unless may_use_simd() returns true.
+ * Task context in the FPSIMD registers is saved back to memory as necessary.
+ *
+ * A matching call to kernel_neon_end() must be made before returning from the
+ * calling context.
+ *
+ * The caller may freely use the FPSIMD registers until kernel_neon_end() is
+ * called.
+ */
+void kernel_neon_begin(void)
+{
+	if (WARN_ON(!system_supports_fpsimd()))
+		return;
+
+	BUG_ON(!may_use_simd());
+
+	get_cpu_fpsimd_context();
+
+	/* Save unsaved fpsimd state, if any: */
+	fpsimd_save();
+
+	/* Invalidate any task state remaining in the fpsimd regs: */
+	fpsimd_flush_cpu_state();
+}
+EXPORT_SYMBOL_GPL(kernel_neon_begin);
+
+/*
+ * kernel_neon_end(): give the CPU FPSIMD registers back to the current task
+ *
+ * Must be called from a context in which kernel_neon_begin() was previously
+ * called, with no call to kernel_neon_end() in the meantime.
+ *
+ * The caller must not use the FPSIMD registers after this function is called,
+ * unless kernel_neon_begin() is called again in the meantime.
+ */
+void kernel_neon_end(void)
+{
+	if (!system_supports_fpsimd())
+		return;
+
+	put_cpu_fpsimd_context();
+}
+EXPORT_SYMBOL_GPL(kernel_neon_end);
+
+#ifdef CONFIG_EFI
+
+static DEFINE_PER_CPU(struct user_fpsimd_state, efi_fpsimd_state);
+static DEFINE_PER_CPU(bool, efi_fpsimd_state_used);
+static DEFINE_PER_CPU(bool, efi_sve_state_used);
+static DEFINE_PER_CPU(bool, efi_sm_state);
+
+/*
+ * EFI runtime services support functions
+ *
+ * The ABI for EFI runtime services allows EFI to use FPSIMD during the call.
+ * This means that for EFI (and only for EFI), we have to assume that FPSIMD
+ * is always used rather than being an optional accelerator.
+ *
+ * These functions provide the necessary support for ensuring FPSIMD
+ * save/restore in the contexts from which EFI is used.
+ *
+ * Do not use them for any other purpose -- if tempted to do so, you are
+ * either doing something wrong or you need to propose some refactoring.
+ */
+
+/*
+ * __efi_fpsimd_begin(): prepare FPSIMD for making an EFI runtime services call
+ */
+void __efi_fpsimd_begin(void)
+{
+	if (!system_supports_fpsimd())
+		return;
+
+	WARN_ON(preemptible());
+
+	if (may_use_simd()) {
+		kernel_neon_begin();
+	} else {
+		/*
+		 * If !efi_sve_state, SVE can't be in use yet and doesn't need
+		 * preserving:
+		 */
+		if (system_supports_sve() && likely(efi_sve_state)) {
+			char *sve_state = this_cpu_ptr(efi_sve_state);
+			bool ffr = true;
+			u64 svcr;
+
+			__this_cpu_write(efi_sve_state_used, true);
+
+			if (system_supports_sme()) {
+				svcr = read_sysreg_s(SYS_SVCR);
+
+				__this_cpu_write(efi_sm_state,
+						 svcr & SVCR_SM_MASK);
+
+				/*
+				 * Unless we have FA64 FFR does not
+				 * exist in streaming mode.
+				 */
+				if (!system_supports_fa64())
+					ffr = !(svcr & SVCR_SM_MASK);
+			}
+
+			sve_save_state(sve_state + sve_ffr_offset(sve_max_vl()),
+				       &this_cpu_ptr(&efi_fpsimd_state)->fpsr,
+				       ffr);
+
+			if (system_supports_sme())
+				sysreg_clear_set_s(SYS_SVCR,
+						   SVCR_SM_MASK, 0);
+
+		} else {
+			fpsimd_save_state(this_cpu_ptr(&efi_fpsimd_state));
+		}
+
+		__this_cpu_write(efi_fpsimd_state_used, true);
+	}
+}
+
+/*
+ * __efi_fpsimd_end(): clean up FPSIMD after an EFI runtime services call
+ */
+void __efi_fpsimd_end(void)
+{
+	if (!system_supports_fpsimd())
+		return;
+
+	if (!__this_cpu_xchg(efi_fpsimd_state_used, false)) {
+		kernel_neon_end();
+	} else {
+		if (system_supports_sve() &&
+		    likely(__this_cpu_read(efi_sve_state_used))) {
+			char const *sve_state = this_cpu_ptr(efi_sve_state);
+			bool ffr = true;
+
+			/*
+			 * Restore streaming mode; EFI calls are
+			 * normal function calls so should not return in
+			 * streaming mode.
+			 */
+			if (system_supports_sme()) {
+				if (__this_cpu_read(efi_sm_state)) {
+					sysreg_clear_set_s(SYS_SVCR,
+							   0,
+							   SVCR_SM_MASK);
+
+					/*
+					 * Unless we have FA64 FFR does not
+					 * exist in streaming mode.
+					 */
+					if (!system_supports_fa64())
+						ffr = false;
+				}
+			}
+
+			sve_load_state(sve_state + sve_ffr_offset(sve_max_vl()),
+				       &this_cpu_ptr(&efi_fpsimd_state)->fpsr,
+				       ffr);
+
+			__this_cpu_write(efi_sve_state_used, false);
+		} else {
+			fpsimd_load_state(this_cpu_ptr(&efi_fpsimd_state));
+		}
+	}
+}
+
+#endif /* CONFIG_EFI */
+
+#endif /* CONFIG_KERNEL_MODE_NEON */
+
+#ifdef CONFIG_CPU_PM
+static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
+				  unsigned long cmd, void *v)
+{
+	switch (cmd) {
+	case CPU_PM_ENTER:
+		fpsimd_save_and_flush_cpu_state();
+		break;
+	case CPU_PM_EXIT:
+		break;
+	case CPU_PM_ENTER_FAILED:
+	default:
+		return NOTIFY_DONE;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block fpsimd_cpu_pm_notifier_block = {
+	.notifier_call = fpsimd_cpu_pm_notifier,
+};
+
+static void __init fpsimd_pm_init(void)
+{
+	cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
+}
+
+#else
+static inline void fpsimd_pm_init(void) { }
+#endif /* CONFIG_CPU_PM */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int fpsimd_cpu_dead(unsigned int cpu)
+{
+	per_cpu(fpsimd_last_state.st, cpu) = NULL;
+	return 0;
+}
+
+static inline void fpsimd_hotplug_init(void)
+{
+	cpuhp_setup_state_nocalls(CPUHP_ARM64_FPSIMD_DEAD, "arm64/fpsimd:dead",
+				  NULL, fpsimd_cpu_dead);
+}
+
+#else
+static inline void fpsimd_hotplug_init(void) { }
+#endif
+
+/*
+ * FP/SIMD support code initialisation.
+ */
+static int __init fpsimd_init(void)
+{
+	if (cpu_have_named_feature(FP)) {
+		fpsimd_pm_init();
+		fpsimd_hotplug_init();
+	} else {
+		pr_notice("Floating-point is not implemented\n");
+	}
+
+	if (!cpu_have_named_feature(ASIMD))
+		pr_notice("Advanced SIMD is not implemented\n");
+
+
+	sve_sysctl_init();
+	sme_sysctl_init();
+
+	return 0;
+}
+core_initcall(fpsimd_init);