RISC-V: hwprobe: Expose Zicbom extension and its block size

Expose Zicbom through hwprobe and also provide a key to extract its
respective block size.

[ alex: Fix merge conflicts and hwprobe numbering ]

Reviewed-by: Andrew Jones <[e-mail]>
Reviewed-by: Samuel Holland <[e-mail]>
Signed-off-by: Yunhui Cui <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Ghiti <[e-mail]>

Documentation/arch/riscv/hwprobe.rst

···
        defined in the RISC-V ISA manual starting from commit 4dc23d6229de
        ("Added Chapter title to BF16").
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZICBOM`: The Zicbom extension is supported, as
+       ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated.  Returns similar values to
      :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was
      mistakenly classified as a bitmask rather than a value.
···
     * :c:macro:`RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR`: The xtheadvector vendor
         extension is supported in the T-Head ISA extensions spec starting from
 	commit a18c801634 ("Add T-Head VECTOR vendor extension. ").
+
+* :c:macro:`RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE`: An unsigned int which
+  represents the size of the Zicbom block in bytes.

arch/riscv/include/asm/hwprobe.h

···
 
 #include <uapi/asm/hwprobe.h>
 
-#define RISCV_HWPROBE_MAX_KEY 11
+#define RISCV_HWPROBE_MAX_KEY 12
 
 static inline bool riscv_hwprobe_key_is_valid(__s64 key)
 {

arch/riscv/include/uapi/asm/hwprobe.h

···
 #define		RISCV_HWPROBE_EXT_ZFBFMIN	(1ULL << 52)
 #define		RISCV_HWPROBE_EXT_ZVFBFMIN	(1ULL << 53)
 #define		RISCV_HWPROBE_EXT_ZVFBFWMA	(1ULL << 54)
+#define		RISCV_HWPROBE_EXT_ZICBOM	(1ULL << 55)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)
···
 #define		RISCV_HWPROBE_MISALIGNED_VECTOR_FAST		3
 #define		RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED	4
 #define RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0	11
+#define RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE	12
 /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
 
 /* Flags */

arch/riscv/kernel/sys_hwprobe.c

···
 		EXT_KEY(ZCA);
 		EXT_KEY(ZCB);
 		EXT_KEY(ZCMOP);
+		EXT_KEY(ZICBOM);
 		EXT_KEY(ZICBOZ);
 		EXT_KEY(ZICNTR);
 		EXT_KEY(ZICOND);
···
 	pair->value &= ~missing;
 }
 
-static bool hwprobe_ext0_has(const struct cpumask *cpus, unsigned long ext)
+static bool hwprobe_ext0_has(const struct cpumask *cpus, u64 ext)
 {
 	struct riscv_hwprobe pair;
 
···
 		pair->value = 0;
 		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOZ))
 			pair->value = riscv_cboz_block_size;
+		break;
+	case RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE:
+		pair->value = 0;
+		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOM))
+			pair->value = riscv_cbom_block_size;
 		break;
 	case RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS:
 		pair->value = user_max_virt_addr();