target/riscv: Introduce extension implied rules definition

RISCVCPUImpliedExtsRule is created to store the implied rules.
'is_misa' flag is used to distinguish whether the rule is derived
from the MISA or other extensions.
'ext' stores the MISA bit if 'is_misa' is true. Otherwise, it stores
the offset of the extension defined in RISCVCPUConfig. 'ext' will also
serve as the key of the hash tables to look up the rule in the following
commit.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>
Tested-by: Max Chou <max.chou@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240625114629.27793-2-frank.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -2250,6 +2250,14 @@ RISCVCPUProfile *riscv_profiles[] = {
     NULL,
 };
 
+RISCVCPUImpliedExtsRule *riscv_misa_ext_implied_rules[] = {
+    NULL
+};
+
+RISCVCPUImpliedExtsRule *riscv_multi_ext_implied_rules[] = {
+    NULL
+};
+
 static Property riscv_cpu_properties[] = {
     DEFINE_PROP_BOOL("debug", RISCVCPU, cfg.debug, true),
 

target/riscv/cpu.h

@@ -124,6 +124,29 @@ typedef enum {
     EXT_STATUS_DIRTY,
 } RISCVExtStatus;
 
+typedef struct riscv_cpu_implied_exts_rule {
+#ifndef CONFIG_USER_ONLY
+    /*
+     * Bitmask indicates the rule enabled status for the harts.
+     * This enhancement is only available in system-mode QEMU,
+     * as we don't have a good way (e.g. mhartid) to distinguish
+     * the SMP cores in user-mode QEMU.
+     */
+    unsigned long *enabled;
+#endif
+    /* True if this is a MISA implied rule. */
+    bool is_misa;
+    /* ext is MISA bit if is_misa flag is true, else multi extension offset. */
+    const uint32_t ext;
+    const uint32_t implied_misa_exts;
+    const uint32_t implied_multi_exts[];
+} RISCVCPUImpliedExtsRule;
+
+extern RISCVCPUImpliedExtsRule *riscv_misa_ext_implied_rules[];
+extern RISCVCPUImpliedExtsRule *riscv_multi_ext_implied_rules[];
+
+#define RISCV_IMPLIED_EXTS_RULE_END -1
+
 #define MMU_USER_IDX 3
 
 #define MAX_RISCV_PMPS (16)