target/riscv: Implement hgeie and hgeip CSRs

The hgeie and hgeip CSRs are required for emulating an external
interrupt controller capable of injecting virtual external interrupt
to Guest/VM running at VS-level.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Message-id: 20220204174700.534953-4-anup@brainfault.org
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 30 insertions, 13 deletions

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index c635ffb089..b23195b479 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -883,7 +883,7 @@ static RISCVException rmw_mip(CPURISCVState *env, int csrno,
     RISCVCPU *cpu = env_archcpu(env);
     /* Allow software control of delegable interrupts not claimed by hardware */
     target_ulong mask = write_mask & delegable_ints & ~env->miclaim;
-    uint32_t old_mip;
+    uint32_t gin, old_mip;
 
     if (mask) {
         old_mip = riscv_cpu_update_mip(cpu, mask, (new_value & mask));
@@ -891,6 +891,11 @@ static RISCVException rmw_mip(CPURISCVState *env, int csrno,
         old_mip = env->mip;
     }
 
+    if (csrno != CSR_HVIP) {
+        gin = get_field(env->hstatus, HSTATUS_VGEIN);
+        old_mip |= (env->hgeip & ((target_ulong)1 << gin)) ? MIP_VSEIP : 0;
+    }
+
     if (ret_value) {
         *ret_value = old_mip;
     }
@@ -1089,7 +1094,7 @@ static RISCVException rmw_vsip(CPURISCVState *env, int csrno,
                                target_ulong new_value, target_ulong write_mask)
 {
     /* Shift the S bits to their VS bit location in mip */
-    int ret = rmw_mip(env, 0, ret_value, new_value << 1,
+    int ret = rmw_mip(env, csrno, ret_value, new_value << 1,
                       (write_mask << 1) & vsip_writable_mask & env->hideleg);
 
     if (ret_value) {
@@ -1109,7 +1114,7 @@ static RISCVException rmw_sip(CPURISCVState *env, int csrno,
     if (riscv_cpu_virt_enabled(env)) {
         ret = rmw_vsip(env, CSR_VSIP, ret_value, new_value, write_mask);
     } else {
-        ret = rmw_mip(env, CSR_MSTATUS, ret_value, new_value,
+        ret = rmw_mip(env, csrno, ret_value, new_value,
                       write_mask & env->mideleg & sip_writable_mask);
     }
 
@@ -1228,7 +1233,7 @@ static RISCVException rmw_hvip(CPURISCVState *env, int csrno,
                                target_ulong *ret_value,
                                target_ulong new_value, target_ulong write_mask)
 {
-    int ret = rmw_mip(env, 0, ret_value, new_value,
+    int ret = rmw_mip(env, csrno, ret_value, new_value,
                       write_mask & hvip_writable_mask);
 
     if (ret_value) {
@@ -1241,7 +1246,7 @@ static RISCVException rmw_hip(CPURISCVState *env, int csrno,
                               target_ulong *ret_value,
                               target_ulong new_value, target_ulong write_mask)
 {
-    int ret = rmw_mip(env, 0, ret_value, new_value,
+    int ret = rmw_mip(env, csrno, ret_value, new_value,
                       write_mask & hip_writable_mask);
 
     if (ret_value) {
@@ -1278,15 +1283,27 @@ static RISCVException write_hcounteren(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
-static RISCVException write_hgeie(CPURISCVState *env, int csrno,
-                                  target_ulong val)
+static RISCVException read_hgeie(CPURISCVState *env, int csrno,
+                                 target_ulong *val)
 {
     if (val) {
-        qemu_log_mask(LOG_UNIMP, "No support for a non-zero GEILEN.");
+        *val = env->hgeie;
     }
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException write_hgeie(CPURISCVState *env, int csrno,
+                                  target_ulong val)
+{
+    /* Only GEILEN:1 bits implemented and BIT0 is never implemented */
+    val &= ((((target_ulong)1) << env->geilen) - 1) << 1;
+    env->hgeie = val;
+    /* Update mip.SGEIP bit */
+    riscv_cpu_update_mip(env_archcpu(env), MIP_SGEIP,
+                         BOOL_TO_MASK(!!(env->hgeie & env->hgeip)));
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException read_htval(CPURISCVState *env, int csrno,
                                  target_ulong *val)
 {
@@ -1314,11 +1331,11 @@ static RISCVException write_htinst(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
-static RISCVException write_hgeip(CPURISCVState *env, int csrno,
-                                  target_ulong val)
+static RISCVException read_hgeip(CPURISCVState *env, int csrno,
+                                 target_ulong *val)
 {
     if (val) {
-        qemu_log_mask(LOG_UNIMP, "No support for a non-zero GEILEN.");
+        *val = env->hgeip;
     }
     return RISCV_EXCP_NONE;
 }
@@ -2148,10 +2165,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_HIP]         = { "hip",         hmode,   NULL,   NULL,     rmw_hip           },
     [CSR_HIE]         = { "hie",         hmode,   read_hie,         write_hie         },
     [CSR_HCOUNTEREN]  = { "hcounteren",  hmode,   read_hcounteren,  write_hcounteren  },
-    [CSR_HGEIE]       = { "hgeie",       hmode,   read_zero,        write_hgeie       },
+    [CSR_HGEIE]       = { "hgeie",       hmode,   read_hgeie,       write_hgeie       },
     [CSR_HTVAL]       = { "htval",       hmode,   read_htval,       write_htval       },
     [CSR_HTINST]      = { "htinst",      hmode,   read_htinst,      write_htinst      },
-    [CSR_HGEIP]       = { "hgeip",       hmode,   read_zero,        write_hgeip       },
+    [CSR_HGEIP]       = { "hgeip",       hmode,   read_hgeip,       NULL              },
     [CSR_HGATP]       = { "hgatp",       hmode,   read_hgatp,       write_hgatp       },
     [CSR_HTIMEDELTA]  = { "htimedelta",  hmode,   read_htimedelta,  write_htimedelta  },
     [CSR_HTIMEDELTAH] = { "htimedeltah", hmode32, read_htimedeltah, write_htimedeltah },