Re: [PATCH v4 03/18] riscv: sbi: add FWFT extension interface

On Mon, Mar 17, 2025 at 06:06:09PM +0100, Clément Léger wrote:

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@rivosinc.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);
  

Let flags stick out. We have 100 chars.

• }

+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

sbi_fwft_local_set_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

Otherwise,

Reviewed-by: Andrew Jones ajones@ventanamicro.com