target/riscv: Implement AIA hvictl and hviprioX CSRs

The AIA hvictl and hviprioX CSRs allow hypervisor to control
interrupts visible at VS-level. This patch implements AIA hvictl
and hviprioX 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>
Message-id: 20220204174700.534953-12-anup@brainfault.org
[ Changes by AF:
 - Fix possible unintilised variable error in rmw_sie()
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -209,6 +209,7 @@ struct CPURISCVState {
     uint64_t htimedelta;
 
     /* Hypervisor controlled virtual interrupt priorities */
+    target_ulong hvictl;
     uint8_t hviprio[64];
 
     /* Upper 64-bits of 128-bit CSRs */
@@ -512,6 +513,7 @@ static inline RISCVMXL riscv_cpu_mxl(CPURISCVState *env)
     return env->misa_mxl;
 }
 #endif
+#define riscv_cpu_mxl_bits(env) (1UL << (4 + riscv_cpu_mxl(env)))
 
 #if defined(TARGET_RISCV32)
 #define cpu_recompute_xl(env)  ((void)(env), MXL_RV32)

target/riscv/csr.c

@@ -234,6 +234,15 @@ static RISCVException pointer_masking(CPURISCVState *env, int csrno)
     return RISCV_EXCP_ILLEGAL_INST;
 }
 
+static int aia_hmode(CPURISCVState *env, int csrno)
+{
+    if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+     }
+
+     return hmode(env, csrno);
+}
+
 static int aia_hmode32(CPURISCVState *env, int csrno)
 {
     if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
@@ -1142,6 +1151,9 @@ static RISCVException rmw_sie64(CPURISCVState *env, int csrno,
     uint64_t mask = env->mideleg & S_MODE_INTERRUPTS;
 
     if (riscv_cpu_virt_enabled(env)) {
+        if (env->hvictl & HVICTL_VTI) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
         ret = rmw_vsie64(env, CSR_VSIE, ret_val, new_val, wr_mask);
     } else {
         ret = rmw_mie64(env, csrno, ret_val, new_val, wr_mask & mask);
@@ -1162,7 +1174,7 @@ static RISCVException rmw_sie(CPURISCVState *env, int csrno,
     RISCVException ret;
 
     ret = rmw_sie64(env, csrno, &rval, new_val, wr_mask);
-    if (ret_val) {
+    if (ret == RISCV_EXCP_NONE && ret_val) {
         *ret_val = rval;
     }
 
@@ -1355,6 +1367,9 @@ static RISCVException rmw_sip64(CPURISCVState *env, int csrno,
     uint64_t mask = env->mideleg & sip_writable_mask;
 
     if (riscv_cpu_virt_enabled(env)) {
+        if (env->hvictl & HVICTL_VTI) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
         ret = rmw_vsip64(env, CSR_VSIP, ret_val, new_val, wr_mask);
     } else {
         ret = rmw_mip64(env, csrno, ret_val, new_val, wr_mask & mask);
@@ -1741,6 +1756,110 @@ static RISCVException write_htimedeltah(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static int read_hvictl(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->hvictl;
+    return RISCV_EXCP_NONE;
+}
+
+static int write_hvictl(CPURISCVState *env, int csrno, target_ulong val)
+{
+    env->hvictl = val & HVICTL_VALID_MASK;
+    return RISCV_EXCP_NONE;
+}
+
+static int read_hvipriox(CPURISCVState *env, int first_index,
+                         uint8_t *iprio, target_ulong *val)
+{
+    int i, irq, rdzero, num_irqs = 4 * (riscv_cpu_mxl_bits(env) / 32);
+
+    /* First index has to be a multiple of number of irqs per register */
+    if (first_index % num_irqs) {
+        return (riscv_cpu_virt_enabled(env)) ?
+               RISCV_EXCP_VIRT_INSTRUCTION_FAULT : RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    /* Fill-up return value */
+    *val = 0;
+    for (i = 0; i < num_irqs; i++) {
+        if (riscv_cpu_hviprio_index2irq(first_index + i, &irq, &rdzero)) {
+            continue;
+        }
+        if (rdzero) {
+            continue;
+        }
+        *val |= ((target_ulong)iprio[irq]) << (i * 8);
+    }
+
+    return RISCV_EXCP_NONE;
+}
+
+static int write_hvipriox(CPURISCVState *env, int first_index,
+                          uint8_t *iprio, target_ulong val)
+{
+    int i, irq, rdzero, num_irqs = 4 * (riscv_cpu_mxl_bits(env) / 32);
+
+    /* First index has to be a multiple of number of irqs per register */
+    if (first_index % num_irqs) {
+        return (riscv_cpu_virt_enabled(env)) ?
+               RISCV_EXCP_VIRT_INSTRUCTION_FAULT : RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    /* Fill-up priority arrary */
+    for (i = 0; i < num_irqs; i++) {
+        if (riscv_cpu_hviprio_index2irq(first_index + i, &irq, &rdzero)) {
+            continue;
+        }
+        if (rdzero) {
+            iprio[irq] = 0;
+        } else {
+            iprio[irq] = (val >> (i * 8)) & 0xff;
+        }
+    }
+
+    return RISCV_EXCP_NONE;
+}
+
+static int read_hviprio1(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    return read_hvipriox(env, 0, env->hviprio, val);
+}
+
+static int write_hviprio1(CPURISCVState *env, int csrno, target_ulong val)
+{
+    return write_hvipriox(env, 0, env->hviprio, val);
+}
+
+static int read_hviprio1h(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    return read_hvipriox(env, 4, env->hviprio, val);
+}
+
+static int write_hviprio1h(CPURISCVState *env, int csrno, target_ulong val)
+{
+    return write_hvipriox(env, 4, env->hviprio, val);
+}
+
+static int read_hviprio2(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    return read_hvipriox(env, 8, env->hviprio, val);
+}
+
+static int write_hviprio2(CPURISCVState *env, int csrno, target_ulong val)
+{
+    return write_hvipriox(env, 8, env->hviprio, val);
+}
+
+static int read_hviprio2h(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    return read_hvipriox(env, 12, env->hviprio, val);
+}
+
+static int write_hviprio2h(CPURISCVState *env, int csrno, target_ulong val)
+{
+    return write_hvipriox(env, 12, env->hviprio, val);
+}
+
 /* Virtual CSR Registers */
 static RISCVException read_vsstatus(CPURISCVState *env, int csrno,
                                     target_ulong *val)
@@ -2534,9 +2653,16 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MTVAL2]      = { "mtval2",      hmode,   read_mtval2,      write_mtval2      },
     [CSR_MTINST]      = { "mtinst",      hmode,   read_mtinst,      write_mtinst      },
 
+    /* Virtual Interrupts and Interrupt Priorities (H-extension with AIA) */
+    [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_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 },
     [CSR_VSIEH]       = { "vsieh",       aia_hmode32, NULL, NULL, rmw_vsieh },
     [CSR_VSIPH]       = { "vsiph",       aia_hmode32, NULL, NULL, rmw_vsiph },
 

target/riscv/machine.c

@@ -92,6 +92,8 @@ static const VMStateDescription vmstate_hyper = {
         VMSTATE_UINTTL(env.hgeie, RISCVCPU),
         VMSTATE_UINTTL(env.hgeip, RISCVCPU),
         VMSTATE_UINT64(env.htimedelta, RISCVCPU),
+
+        VMSTATE_UINTTL(env.hvictl, RISCVCPU),
         VMSTATE_UINT8_ARRAY(env.hviprio, RISCVCPU, 64),
 
         VMSTATE_UINT64(env.vsstatus, RISCVCPU),