[PW_SID:963139] riscv: add SBI FWFT misaligned exception delegation support

arch/riscv/include/asm/cpufeature.h

@@ -67,8 +67,9 @@ void __init riscv_user_isa_enable(void);
 	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), _validate)
 
 bool __init check_unaligned_access_emulated_all_cpus(void);
+void unaligned_access_init(void);
+int cpu_online_unaligned_access_init(unsigned int cpu);
 #if defined(CONFIG_RISCV_SCALAR_MISALIGNED)
-void check_unaligned_access_emulated(struct work_struct *work __always_unused);
 void unaligned_emulation_finish(void);
 bool unaligned_ctl_available(void);
 DECLARE_PER_CPU(long, misaligned_access_speed);
@@ -79,6 +80,15 @@ static inline bool unaligned_ctl_available(void)
 }
 #endif
 
+#ifdef CONFIG_RISCV_MISALIGNED
+bool misaligned_traps_can_delegate(void);
+#else
+static inline bool misaligned_traps_can_delegate(void)
+{
+	return false;
+}
+#endif
+
 bool __init check_vector_unaligned_access_emulated_all_cpus(void);
 #if defined(CONFIG_RISCV_VECTOR_MISALIGNED)
 void check_vector_unaligned_access_emulated(struct work_struct *work __always_unused);

arch/riscv/include/asm/kvm_host.h

@@ -19,6 +19,7 @@
 #include <asm/kvm_vcpu_fp.h>
 #include <asm/kvm_vcpu_insn.h>
 #include <asm/kvm_vcpu_sbi.h>
+#include <asm/kvm_vcpu_sbi_fwft.h>
 #include <asm/kvm_vcpu_timer.h>
 #include <asm/kvm_vcpu_pmu.h>
 
@@ -281,6 +282,9 @@ struct kvm_vcpu_arch {
 	/* Performance monitoring context */
 	struct kvm_pmu pmu_context;
 
+	/* Firmware feature SBI extension context */
+	struct kvm_sbi_fwft fwft_context;
+
 	/* 'static' configurations which are set only once */
 	struct kvm_vcpu_config cfg;
 
@@ -407,7 +411,6 @@ void __kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
 bool kvm_riscv_vcpu_stopped(struct kvm_vcpu *vcpu);
 
-void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);
 
 #endif /* __RISCV_KVM_HOST_H__ */

arch/riscv/include/asm/kvm_vcpu_sbi.h

@@ -49,6 +49,15 @@ struct kvm_vcpu_sbi_extension {
 
 	/* Extension specific probe function */
 	unsigned long (*probe)(struct kvm_vcpu *vcpu);
+
+	/*
+	 * Init/deinit function called once during VCPU init/destroy. These
+	 * might be use if the SBI extensions need to allocate or do specific
+	 * init time only configuration.
+	 */
+	int (*init)(struct kvm_vcpu *vcpu);
+	void (*deinit)(struct kvm_vcpu *vcpu);
+	void (*reset)(struct kvm_vcpu *vcpu);
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
@@ -69,6 +78,8 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
 bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
 int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
 void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_sbi_reset(struct kvm_vcpu *vcpu);
 
 int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu, unsigned long reg_num,
 				   unsigned long *reg_val);
@@ -87,6 +98,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_susp;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
 

arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h

@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2025 Rivos Inc.
+ *
+ * Authors:
+ *     Clément Léger <cleger@rivosinc.com>
+ */
+
+#ifndef __KVM_VCPU_RISCV_FWFT_H
+#define __KVM_VCPU_RISCV_FWFT_H
+
+#include <asm/sbi.h>
+
+struct kvm_sbi_fwft_feature;
+
+struct kvm_sbi_fwft_config {
+	const struct kvm_sbi_fwft_feature *feature;
+	bool supported;
+	unsigned long flags;
+};
+
+/* FWFT data structure per vcpu */
+struct kvm_sbi_fwft {
+	struct kvm_sbi_fwft_config *configs;
+};
+
+#define vcpu_to_fwft(vcpu) (&(vcpu)->arch.fwft_context)
+
+#endif /* !__KVM_VCPU_RISCV_FWFT_H */

arch/riscv/include/asm/sbi.h

@@ -35,6 +35,7 @@ enum sbi_ext_id {
 	SBI_EXT_DBCN = 0x4442434E,
 	SBI_EXT_STA = 0x535441,
 	SBI_EXT_NACL = 0x4E41434C,
+	SBI_EXT_FWFT = 0x46574654,
 
 	/* Experimentals extensions must lie within this range */
 	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
@@ -402,6 +403,33 @@ enum sbi_ext_nacl_feature {
 #define SBI_NACL_SHMEM_SRET_X(__i)		((__riscv_xlen / 8) * (__i))
 #define SBI_NACL_SHMEM_SRET_X_LAST		31
 
+/* SBI function IDs for FW feature extension */
+#define SBI_EXT_FWFT_SET		0x0
+#define SBI_EXT_FWFT_GET		0x1
+
+enum sbi_fwft_feature_t {
+	SBI_FWFT_MISALIGNED_EXC_DELEG		= 0x0,
+	SBI_FWFT_LANDING_PAD			= 0x1,
+	SBI_FWFT_SHADOW_STACK			= 0x2,
+	SBI_FWFT_DOUBLE_TRAP			= 0x3,
+	SBI_FWFT_PTE_AD_HW_UPDATING		= 0x4,
+	SBI_FWFT_POINTER_MASKING_PMLEN		= 0x5,
+	SBI_FWFT_LOCAL_RESERVED_START		= 0x6,
+	SBI_FWFT_LOCAL_RESERVED_END		= 0x3fffffff,
+	SBI_FWFT_LOCAL_PLATFORM_START		= 0x40000000,
+	SBI_FWFT_LOCAL_PLATFORM_END		= 0x7fffffff,
+
+	SBI_FWFT_GLOBAL_RESERVED_START		= 0x80000000,
+	SBI_FWFT_GLOBAL_RESERVED_END		= 0xbfffffff,
+	SBI_FWFT_GLOBAL_PLATFORM_START		= 0xc0000000,
+	SBI_FWFT_GLOBAL_PLATFORM_END		= 0xffffffff,
+};
+
+#define SBI_FWFT_PLATFORM_FEATURE_BIT		BIT(30)
+#define SBI_FWFT_GLOBAL_FEATURE_BIT		BIT(31)
+
+#define SBI_FWFT_SET_FLAG_LOCK			BIT(0)
+
 /* SBI spec version fields */
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
@@ -419,6 +447,11 @@ enum sbi_ext_nacl_feature {
 #define SBI_ERR_ALREADY_STARTED -7
 #define SBI_ERR_ALREADY_STOPPED -8
 #define SBI_ERR_NO_SHMEM	-9
+#define SBI_ERR_INVALID_STATE	-10
+#define SBI_ERR_BAD_RANGE	-11
+#define SBI_ERR_TIMEOUT		-12
+#define SBI_ERR_IO		-13
+#define SBI_ERR_DENIED_LOCKED	-14
 
 extern unsigned long sbi_spec_version;
 struct sbiret {
@@ -470,6 +503,23 @@ int sbi_remote_hfence_vvma_asid(const struct cpumask *cpu_mask,
 				unsigned long asid);
 long sbi_probe_extension(int ext);
 
+int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags);
+int sbi_fwft_set_cpumask(const cpumask_t *mask, u32 feature,
+			 unsigned long value, unsigned long flags);
+/**
+ * sbi_fwft_set_online_cpus() - Set a feature on all online cpus
+ * @feature: The feature to be set
+ * @value: The feature value to be set
+ * @flags: FWFT feature set flags
+ *
+ * Return: 0 on success, appropriate linux error code otherwise.
+ */
+static inline int sbi_fwft_set_online_cpus(u32 feature, unsigned long value,
+					   unsigned long flags)
+{
+	return sbi_fwft_set_cpumask(cpu_online_mask, feature, value, flags);
+}
+
 /* Check if current SBI specification version is 0.1 or not */
 static inline int sbi_spec_is_0_1(void)
 {
@@ -503,11 +553,21 @@ static inline int sbi_err_map_linux_errno(int err)
 	case SBI_SUCCESS:
 		return 0;
 	case SBI_ERR_DENIED:
+	case SBI_ERR_DENIED_LOCKED:
 		return -EPERM;
 	case SBI_ERR_INVALID_PARAM:
+	case SBI_ERR_INVALID_STATE:
 		return -EINVAL;
+	case SBI_ERR_BAD_RANGE:
+		return -ERANGE;
 	case SBI_ERR_INVALID_ADDRESS:
 		return -EFAULT;
+	case SBI_ERR_NO_SHMEM:
+		return -ENOMEM;
+	case SBI_ERR_TIMEOUT:
+		return -ETIMEDOUT;
+	case SBI_ERR_IO:
+		return -EIO;
 	case SBI_ERR_NOT_SUPPORTED:
 	case SBI_ERR_FAILURE:
 	default:

arch/riscv/include/uapi/asm/kvm.h

@@ -204,6 +204,7 @@ enum KVM_RISCV_SBI_EXT_ID {
 	KVM_RISCV_SBI_EXT_DBCN,
 	KVM_RISCV_SBI_EXT_STA,
 	KVM_RISCV_SBI_EXT_SUSP,
+	KVM_RISCV_SBI_EXT_FWFT,
 	KVM_RISCV_SBI_EXT_MAX,
 };
 

arch/riscv/kernel/sbi.c

@@ -299,6 +299,76 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
 	return 0;
 }
 
+static bool sbi_fwft_supported;
+
+struct fwft_set_req {
+	u32 feature;
+	unsigned long value;
+	unsigned long flags;
+	atomic_t error;
+};
+
+static void cpu_sbi_fwft_set(void *arg)
+{
+	struct fwft_set_req *req = arg;
+	int ret;
+
+	ret = sbi_fwft_set(req->feature, req->value, req->flags);
+	if (ret)
+		atomic_set(&req->error, ret);
+}
+
+/**
+ * sbi_fwft_set() - Set a feature on the local hart
+ * @feature: The feature ID to be set
+ * @value: The feature value to be set
+ * @flags: FWFT feature set flags
+ *
+ * Return: 0 on success, appropriate linux error code otherwise.
+ */
+int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
+{
+	struct sbiret ret;
+
+	if (!sbi_fwft_supported)
+		return -EOPNOTSUPP;
+
+	ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET,
+			feature, value, flags, 0, 0, 0);
+
+	return sbi_err_map_linux_errno(ret.error);
+}
+
+/**
+ * sbi_fwft_set_cpumask() - Set a feature for the specified cpumask
+ * @mask: CPU mask of cpus that need the feature to be set
+ * @feature: The feature ID to be set
+ * @value: The feature value to be set
+ * @flags: FWFT feature set flags
+ *
+ * Return: 0 on success, appropriate linux error code otherwise.
+ */
+int sbi_fwft_set_cpumask(const cpumask_t *mask, u32 feature,
+			       unsigned long value, unsigned long flags)
+{
+	struct fwft_set_req req = {
+		.feature = feature,
+		.value = value,
+		.flags = flags,
+		.error = ATOMIC_INIT(0),
+	};
+
+	if (!sbi_fwft_supported)
+		return -EOPNOTSUPP;
+
+	if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
+		return -EINVAL;
+
+	on_each_cpu_mask(mask, cpu_sbi_fwft_set, &req, 1);
+
+	return atomic_read(&req.error);
+}
+
 /**
  * sbi_set_timer() - Program the timer for next timer event.
  * @stime_value: The value after which next timer event should fire.
@@ -609,19 +679,24 @@ void __init sbi_init(void)
 		} else {
 			__sbi_rfence	= __sbi_rfence_v01;
 		}
-		if ((sbi_spec_version >= sbi_mk_version(0, 3)) &&
+		if (sbi_spec_version >= sbi_mk_version(0, 3) &&
 		    sbi_probe_extension(SBI_EXT_SRST)) {
 			pr_info("SBI SRST extension detected\n");
 			pm_power_off = sbi_srst_power_off;
 			sbi_srst_reboot_nb.notifier_call = sbi_srst_reboot;
 			sbi_srst_reboot_nb.priority = 192;
 			register_restart_handler(&sbi_srst_reboot_nb);
 		}
-		if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
-		    (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
+		if (sbi_spec_version >= sbi_mk_version(2, 0) &&
+		    sbi_probe_extension(SBI_EXT_DBCN) > 0) {
 			pr_info("SBI DBCN extension detected\n");
 			sbi_debug_console_available = true;
 		}
+		if (sbi_spec_version >= sbi_mk_version(3, 0) &&
+		    sbi_probe_extension(SBI_EXT_FWFT)) {
+			pr_info("SBI FWFT extension detected\n");
+			sbi_fwft_supported = true;
+		}
 	} else {
 		__sbi_set_timer = __sbi_set_timer_v01;
 		__sbi_send_ipi	= __sbi_send_ipi_v01;