linux-kernel - [PATCH v4 03/18] riscv: sbi: add FWFT extension interface

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Message-ID: <20250317170625.1142870-4-cleger@rivosinc.com>
Date: Mon, 17 Mar 2025 18:06:09 +0100
From: Clément Léger <cleger@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Anup Patel <anup@...infault.org>,
	Atish Patra <atishp@...shpatra.org>,
	Shuah Khan <shuah@...nel.org>,
	Jonathan Corbet <corbet@....net>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-kselftest@...r.kernel.org
Cc: Clément Léger <cleger@...osinc.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Andrew Jones <ajones@...tanamicro.com>
Subject: [PATCH v4 03/18] riscv: sbi: add FWFT extension interface

This SBI extensions enables supervisor mode to control feature that are
under M-mode control (For instance, Svadu menvcfg ADUE bit, Ssdbltrp
DTE, etc). Add an interface to set local features for a specific cpu
mask as well as for the online cpu mask.

Signed-off-by: Clément Léger <cleger@...osinc.com>
---
 arch/riscv/include/asm/sbi.h | 20 +++++++++++
 arch/riscv/kernel/sbi.c      | 69 ++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index d11d22717b49..1cecfa82c2e5 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -503,6 +503,26 @@ int sbi_remote_hfence_vvma_asid(const struct cpumask *cpu_mask,
 				unsigned long asid);
 long sbi_probe_extension(int ext);
 
+int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
+			       unsigned long value, unsigned long flags);
+/**
+ * sbi_fwft_local_set() - 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_local_set(u32 feature, unsigned long value,
+				      unsigned long flags)
+ {
+	 return sbi_fwft_local_set_cpumask(cpu_online_mask, feature, value,
+					   flags);
+ }
+
+int sbi_fwft_get(u32 feature, unsigned long *value);
+int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags);
+
 /* Check if current SBI specification version is 0.1 or not */
 static inline int sbi_spec_is_0_1(void)
 {
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 1989b8cade1b..d41a5642be24 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -299,6 +299,75 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
 	return 0;
 }
 
+/**
+ * sbi_fwft_get() - Get a feature for the local hart
+ * @feature: The feature ID to be set
+ * @value: Will contain the feature value on success
+ *
+ * Return: 0 on success, appropriate linux error code otherwise.
+ */
+int sbi_fwft_get(u32 feature, unsigned long *value)
+{
+	return -EOPNOTSUPP;
+}
+
+/**
+ * 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)
+{
+	return -EOPNOTSUPP;
+}
+
+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_local_set() - 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_local_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 (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.
-- 
2.47.2