[PATCH for-8.2 1/2] target/riscv/cpu.c: add zicntr extension flag

[Daniel Henrique Barboza]

zicntr is the Base Counters and Timers extension described in chapter 12
of the unprivileged spec. It describes support for RDCYCLE, RDTIME and
RDINSTRET.

QEMU already implements it way before it was a discrete extension.
zicntr is part of the RVA22 profile, so let's add it to QEMU to make the
future profile implementation flag complete.

Given than it represents an already existing feature, default it to
'true'. Change the realize() time validation to disable it in case its
dependency (icsr) isn't present.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c     | 11 +++++++++++
 target/riscv/cpu_cfg.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 9339c0241d..7ec88659be 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -85,6 +85,7 @@ static const struct isa_ext_data isa_edata_arr[] = {
     ISA_EXT_DATA_ENTRY(zicbom, PRIV_VERSION_1_12_0, ext_icbom),
     ISA_EXT_DATA_ENTRY(zicboz, PRIV_VERSION_1_12_0, ext_icboz),
     ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
+    ISA_EXT_DATA_ENTRY(zicntr, PRIV_VERSION_1_12_0, ext_icntr),
     ISA_EXT_DATA_ENTRY(zicsr, PRIV_VERSION_1_10_0, ext_icsr),
     ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_ifencei),
     ISA_EXT_DATA_ENTRY(zihintpause, PRIV_VERSION_1_10_0, ext_zihintpause),
@@ -1291,6 +1292,10 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, 
Error **errp)
         cpu->cfg.ext_zksh = true;
     }
 
+    if (cpu->cfg.ext_icntr && !cpu->cfg.ext_icsr) {
+        cpu->cfg.ext_icntr = false;
+    }
+
     /*
      * Disable isa extensions based on priv spec after we
      * validated and set everything we need.
@@ -1778,6 +1783,12 @@ static Property riscv_cpu_extensions[] = {
     DEFINE_PROP_BOOL("svnapot", RISCVCPU, cfg.ext_svnapot, false),
     DEFINE_PROP_BOOL("svpbmt", RISCVCPU, cfg.ext_svpbmt, false),
 
+    /*
+     * Always default true - we'll disable it during
+     * realize() if needed.
+     */
+    DEFINE_PROP_BOOL("zicntr", RISCVCPU, cfg.ext_icntr, true),
+
     DEFINE_PROP_BOOL("zba", RISCVCPU, cfg.ext_zba, true),
     DEFINE_PROP_BOOL("zbb", RISCVCPU, cfg.ext_zbb, true),
     DEFINE_PROP_BOOL("zbc", RISCVCPU, cfg.ext_zbc, true),
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index 2bd9510ba3..d36dc12b92 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -62,6 +62,7 @@ struct RISCVCPUConfig {
     bool ext_zksh;
     bool ext_zkt;
     bool ext_ifencei;
+    bool ext_icntr;
     bool ext_icsr;
     bool ext_icbom;
     bool ext_icboz;
-- 
2.41.0