[PATCH v9 12/23] target/riscv: Implement AIA interrupt filtering CSRs

[Anup Patel]

From: Anup Patel <anup.patel@wdc.com>

The AIA specificaiton adds interrupt filtering support for M-mode
and HS-mode. Using AIA interrupt filtering M-mode and H-mode can
take local interrupt 13 or above and selectively inject same local
interrupt to lower privilege modes.

At the moment, we don't have any local interrupts above 12 so we
add dummy implementation (i.e. read zero and ignore write) of AIA
interrupt filtering CSRs.

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>
---
 target/riscv/csr.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 552dae1ef8..00f55f47ed 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -158,6 +158,15 @@ static RISCVException any32(CPURISCVState *env, int csrno)
 
 }
 
+static int aia_any(CPURISCVState *env, int csrno)
+{
+    if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    return any(env, csrno);
+}
+
 static int aia_any32(CPURISCVState *env, int csrno)
 {
     if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
@@ -568,6 +577,12 @@ static RISCVException read_zero(CPURISCVState *env, int 
csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException write_ignore(CPURISCVState *env, int csrno,
+                                   target_ulong val)
+{
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException read_mhartid(CPURISCVState *env, int csrno,
                                    target_ulong *val)
 {
@@ -2598,9 +2613,15 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MTVAL]    = { "mtval",    any,  read_mtval,    write_mtval    },
     [CSR_MIP]      = { "mip",      any,  NULL,    NULL, rmw_mip        },
 
+    /* Virtual Interrupts for Supervisor Level (AIA) */
+    [CSR_MVIEN]      = { "mvien", aia_any, read_zero, write_ignore },
+    [CSR_MVIP]       = { "mvip",  aia_any, read_zero, write_ignore },
+
     /* Machine-Level High-Half CSRs (AIA) */
     [CSR_MIDELEGH] = { "midelegh", aia_any32, NULL, NULL, rmw_midelegh },
     [CSR_MIEH]     = { "mieh",     aia_any32, NULL, NULL, rmw_mieh     },
+    [CSR_MVIENH]   = { "mvienh",   aia_any32, read_zero,  write_ignore },
+    [CSR_MVIPH]    = { "mviph",    aia_any32, read_zero,  write_ignore },
     [CSR_MIPH]     = { "miph",     aia_any32, NULL, NULL, rmw_miph     },
 
     /* Supervisor Trap Setup */
@@ -2654,12 +2675,14 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MTINST]      = { "mtinst",      hmode,   read_mtinst,      
write_mtinst      },
 
     /* Virtual Interrupts and Interrupt Priorities (H-extension with AIA) */
+    [CSR_HVIEN]       = { "hvien",       aia_hmode, read_zero, write_ignore },
     [CSR_HVICTL]      = { "hvictl",      aia_hmode, read_hvictl, write_hvictl 
},
     [CSR_HVIPRIO1]    = { "hviprio1",    aia_hmode, read_hviprio1,   
write_hviprio1 },
     [CSR_HVIPRIO2]    = { "hviprio2",    aia_hmode, read_hviprio2,   
write_hviprio2 },
 
     /* Hypervisor and VS-Level High-Half CSRs (H-extension with AIA) */
     [CSR_HIDELEGH]    = { "hidelegh",    aia_hmode32, NULL, NULL, rmw_hidelegh 
},
+    [CSR_HVIENH]      = { "hvienh",      aia_hmode32, read_zero, write_ignore 
},
     [CSR_HVIPH]       = { "hviph",       aia_hmode32, NULL, NULL, rmw_hviph },
     [CSR_HVIPRIO1H]   = { "hviprio1h",   aia_hmode32, read_hviprio1h, 
write_hviprio1h },
     [CSR_HVIPRIO2H]   = { "hviprio2h",   aia_hmode32, read_hviprio2h, 
write_hviprio2h },
-- 
2.25.1