[PATCH v2 3/3] RISC-V: hwprobe: Expose Zba, Zbb, and Zbs

Evan Green
2023-05-09T18:25:29Z

Add two new bits to the IMA_EXT_0 key for ZBA, ZBB, and ZBS extensions.
These are accurately reported per CPU.

Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

---

Changes in v2:
- Fixed typo s/supporte/supported/ (Conor)
- Fixed copypasta s/IMA_ZBB/EXT_ZBB/ (Conor)
- Added Zbs

Documentation/riscv/hwprobe.rst | 10 ++++++
arch/riscv/include/uapi/asm/hwprobe.h | 3 ++
arch/riscv/kernel/sys_riscv.c | 48 +++++++++++++++++++++++----
3 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/Documentation/riscv/hwprobe.rst b/Documentation/riscv/hwprobe.rst
index 9f0dd62dcb5d..fb25670ef0e5 100644
--- a/Documentation/riscv/hwprobe.rst
+++ b/Documentation/riscv/hwprobe.rst
@@ -64,6 +64,16 @@ The following keys are defined:
* :c:macro:`RISCV_HWPROBE_IMA_C`: The C extension is supported, as defined
by version 2.2 of the RISC-V ISA manual.

+ * :c:macro:`RISCV_HWPROBE_EXT_ZBA`: The Zba address generation extension is
+ supported, as defined in version 1.0 of the Bit-Manipulation ISA
+ extensions.
+
+ * :c:macro:`RISCV_HWPROBE_EXT_ZBB`: The Zbb extension is supported, as defined
+ in version 1.0 of the Bit-Manipulation ISA extensions.
+
+ * :c:macro:`RISCV_HWPROBE_EXT_ZBS`: The Zbs extension is supported, as defined
+ in version 1.0 of the Bit-Manipulation ISA extensions.
+
* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
information about the selected set of processors.

diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
index 8d745a4ad8a2..853f8f6d9a42 100644
--- a/arch/riscv/include/uapi/asm/hwprobe.h
+++ b/arch/riscv/include/uapi/asm/hwprobe.h
@@ -25,6 +25,9 @@ struct riscv_hwprobe {
#define RISCV_HWPROBE_KEY_IMA_EXT_0 4
#define RISCV_HWPROBE_IMA_FD (1 << 0)
#define RISCV_HWPROBE_IMA_C (1 << 1)
+#define RISCV_HWPROBE_EXT_ZBA (1 << 2)
+#define RISCV_HWPROBE_EXT_ZBB (1 << 3)
+#define RISCV_HWPROBE_EXT_ZBS (1 << 4)
#define RISCV_HWPROBE_KEY_CPUPERF_0 5
#define RISCV_HWPROBE_MISALIGNED_UNKNOWN (0 << 0)
#define RISCV_HWPROBE_MISALIGNED_EMULATED (1 << 0)
diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index 5db29683ebee..fe655db19ab4 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -121,6 +121,46 @@ static void hwprobe_arch_id(struct riscv_hwprobe *pair,
pair->value = id;
}

+static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
+ const struct cpumask *cpus)
+{
+ int cpu;
+ u64 missing = 0;
+
+ pair->value = 0;
+ if (has_fpu())
+ pair->value |= RISCV_HWPROBE_IMA_FD;
+
+ if (riscv_isa_extension_available(NULL, c))
+ pair->value |= RISCV_HWPROBE_IMA_C;
+
+ /*
+ * Loop through and record extensions that 1) anyone has, and 2) anyone
+ * doesn't have.
+ */
+ for_each_cpu(cpu, cpus) {
+ struct riscv_isainfo *isainfo = &hart_isa[cpu];
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBA))
+ pair->value |= RISCV_HWPROBE_EXT_ZBA;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBA;
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBB))
+ pair->value |= RISCV_HWPROBE_EXT_ZBB;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBB;
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBS))
+ pair->value |= RISCV_HWPROBE_EXT_ZBS;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBS;
+ }
+
+ /* Now turn off reporting features if any CPU is missing it. */
+ pair->value &= ~missing;
+}
+
static u64 hwprobe_misaligned(const struct cpumask *cpus)
{
int cpu;
@@ -164,13 +204,7 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
break;

case RISCV_HWPROBE_KEY_IMA_EXT_0:
- pair->value = 0;
- if (has_fpu())
- pair->value |= RISCV_HWPROBE_IMA_FD;
-
- if (riscv_isa_extension_available(NULL, c))
- pair->value |= RISCV_HWPROBE_IMA_C;
-
+ hwprobe_isa_ext0(pair, cpus);
break;

case RISCV_HWPROBE_KEY_CPUPERF_0:
--
2.25.1