linux-kernel - [PATCH v4 04/18] riscv: sbi: add SBI FWFT extension calls

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Message-ID: <20250317170625.1142870-5-cleger@rivosinc.com>
Date: Mon, 17 Mar 2025 18:06:10 +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 04/18] riscv: sbi: add SBI FWFT extension calls

Add FWFT extension calls. This will be ratified in SBI V3.0 hence, it is
provided as a separate commit that can be left out if needed.

Signed-off-by: Clément Léger <cleger@...osinc.com>
---
 arch/riscv/kernel/sbi.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index d41a5642be24..54d9ceb7b723 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -299,6 +299,8 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
 	return 0;
 }
 
+static bool sbi_fwft_supported;
+
 /**
  * sbi_fwft_get() - Get a feature for the local hart
  * @feature: The feature ID to be set
@@ -308,7 +310,15 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
  */
 int sbi_fwft_get(u32 feature, unsigned long *value)
 {
-	return -EOPNOTSUPP;
+	struct sbiret ret;
+
+	if (!sbi_fwft_supported)
+		return -EOPNOTSUPP;
+
+	ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_GET,
+			feature, 0, 0, 0, 0, 0);
+
+	return sbi_err_map_linux_errno(ret.error);
 }
 
 /**
@@ -321,7 +331,15 @@ int sbi_fwft_get(u32 feature, unsigned long *value)
  */
 int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
 {
-	return -EOPNOTSUPP;
+	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);
 }
 
 struct fwft_set_req {
@@ -360,6 +378,9 @@ int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
 		.error = ATOMIC_INIT(0),
 	};
 
+	if (!sbi_fwft_supported)
+		return -EOPNOTSUPP;
+
 	if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
 		return -EINVAL;
 
@@ -691,6 +712,11 @@ void __init sbi_init(void)
 			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) > 0)) {
+			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;
-- 
2.47.2