diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index bcc974d276dc..df79e129d097 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -493,12 +493,13 @@ What:		/sys/devices/system/cpu/cpuX/regs/
 		/sys/devices/system/cpu/cpuX/regs/identification/
 		/sys/devices/system/cpu/cpuX/regs/identification/midr_el1
 		/sys/devices/system/cpu/cpuX/regs/identification/revidr_el1
+		/sys/devices/system/cpu/cpuX/regs/identification/smidr_el1
 Date:		June 2016
 Contact:	Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
 Description:	AArch64 CPU registers
 
 		'identification' directory exposes the CPU ID registers for
-		identifying model and revision of the CPU.
+		identifying model and revision of the CPU and SMCU.
 
 What:		/sys/devices/system/cpu/aarch32_el0
 Date:		May 2021
diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
index 115cdec1ae87..fd7a92219eea 100644
--- a/arch/arm64/include/asm/cpu.h
+++ b/arch/arm64/include/asm/cpu.h
@@ -46,6 +46,7 @@ struct cpuinfo_arm64 {
 	u64		reg_midr;
 	u64		reg_revidr;
 	u64		reg_gmid;
+	u64		reg_smidr;
 
 	u64		reg_id_aa64dfr0;
 	u64		reg_id_aa64dfr1;
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 8eff0a34ffd4..7f06df59df2b 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -267,6 +267,7 @@ static struct kobj_type cpuregs_kobj_type = {
 
 CPUREGS_ATTR_RO(midr_el1, midr);
 CPUREGS_ATTR_RO(revidr_el1, revidr);
+CPUREGS_ATTR_RO(smidr_el1, smidr);
 
 static struct attribute *cpuregs_id_attrs[] = {
 	&cpuregs_attr_midr_el1.attr,
@@ -279,6 +280,16 @@ static const struct attribute_group cpuregs_attr_group = {
 	.name = "identification"
 };
 
+static struct attribute *sme_cpuregs_id_attrs[] = {
+	&cpuregs_attr_smidr_el1.attr,
+	NULL
+};
+
+static const struct attribute_group sme_cpuregs_attr_group = {
+	.attrs = sme_cpuregs_id_attrs,
+	.name = "identification"
+};
+
 static int cpuid_cpu_online(unsigned int cpu)
 {
 	int rc;
@@ -296,6 +307,8 @@ static int cpuid_cpu_online(unsigned int cpu)
 	rc = sysfs_create_group(&info->kobj, &cpuregs_attr_group);
 	if (rc)
 		kobject_del(&info->kobj);
+	if (system_supports_sme())
+		rc = sysfs_merge_group(&info->kobj, &sme_cpuregs_attr_group);
 out:
 	return rc;
 }
@@ -423,9 +436,17 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 		info->reg_zcr = read_zcr_features();
 
 	if (IS_ENABLED(CONFIG_ARM64_SME) &&
-	    id_aa64pfr1_sme(info->reg_id_aa64pfr1))
+	    id_aa64pfr1_sme(info->reg_id_aa64pfr1)) {
 		info->reg_smcr = read_smcr_features();
 
+		/*
+		 * We mask out SMPS since even if the hardware
+		 * supports priorities the kernel does not at present
+		 * and we block access to them.
+		 */
+		info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS;
+	}
+
 	cpuinfo_detect_icache_policy(info);
 }
 
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index aecf3071efdd..dd63ffc3a2fa 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -445,7 +445,6 @@ static void fpsimd_save(void)
 
 	if (system_supports_sme()) {
 		u64 *svcr = last->svcr;
-		*svcr = read_sysreg_s(SYS_SVCR);
 
 		*svcr = read_sysreg_s(SYS_SVCR);
 
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index b0980fbb6bc7..3e6d0352d7d3 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -280,6 +280,9 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user)
 
 		vl = task_get_sme_vl(current);
 	} else {
+		if (!system_supports_sve())
+			return -EINVAL;
+
 		vl = task_get_sve_vl(current);
 	}
 
@@ -342,9 +345,14 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user)
 
 #else /* ! CONFIG_ARM64_SVE */
 
-/* Turn any non-optimised out attempts to use these into a link error: */
+static int restore_sve_fpsimd_context(struct user_ctxs *user)
+{
+	WARN_ON_ONCE(1);
+	return -EINVAL;
+}
+
+/* Turn any non-optimised out attempts to use this into a link error: */
 extern int preserve_sve_context(void __user *ctx);
-extern int restore_sve_fpsimd_context(struct user_ctxs *user);
 
 #endif /* ! CONFIG_ARM64_SVE */
 
@@ -649,14 +657,10 @@ static int restore_sigframe(struct pt_regs *regs,
 		if (!user.fpsimd)
 			return -EINVAL;
 
-		if (user.sve) {
-			if (!system_supports_sve())
-				return -EINVAL;
-
+		if (user.sve)
 			err = restore_sve_fpsimd_context(&user);
-		} else {
+		else
 			err = restore_fpsimd_context(user.fpsimd);
-		}
 	}
 
 	if (err == 0 && system_supports_sme() && user.za)