linux-kernel - [PATCH v4 06/21] RISC-V: Add Smcntrpmf extension parsing

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Message-Id: <20250205-counter_delegation-v4-6-835cfa88e3b1@rivosinc.com>
Date: Wed, 05 Feb 2025 23:23:11 -0800
From: Atish Patra <atishp@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Anup Patel <anup@...infault.org>, 
 Atish Patra <atishp@...shpatra.org>, Will Deacon <will@...nel.org>, 
 Mark Rutland <mark.rutland@....com>, Peter Zijlstra <peterz@...radead.org>, 
 Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, 
 Namhyung Kim <namhyung@...nel.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, 
 Adrian Hunter <adrian.hunter@...el.com>, weilin.wang@...el.com
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Conor Dooley <conor@...nel.org>, devicetree@...r.kernel.org, 
 kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org, 
 Atish Patra <atishp@...osinc.com>
Subject: [PATCH v4 06/21] RISC-V: Add Smcntrpmf extension parsing

Smcntrpmf extension allows M-mode to enable privilege mode filtering
for cycle/instret counters. However, the cyclecfg/instretcfg CSRs are
only available only in Ssccfg only Smcntrpmf is present.

That's why, kernel needs to detect presence of Smcntrpmf extension and
enable privilege mode filtering for cycle/instret counters.

Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/include/asm/hwcap.h | 1 +
 arch/riscv/kernel/cpufeature.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 3d6e706fc5b2..b4eddcb57842 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -102,6 +102,7 @@
 #define RISCV_ISA_EXT_SVADU		93
 #define RISCV_ISA_EXT_SSCSRIND		94
 #define RISCV_ISA_EXT_SMCSRIND		95
+#define RISCV_ISA_EXT_SMCNTRPMF         96
 
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index c6da81aa48aa..8f225c9c3055 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -390,6 +390,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
 	__RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
 	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
+	__RISCV_ISA_EXT_DATA(smcntrpmf, RISCV_ISA_EXT_SMCNTRPMF),
 	__RISCV_ISA_EXT_DATA(smcsrind, RISCV_ISA_EXT_SMCSRIND),
 	__RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
 	__RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),

-- 
2.43.0