[PATCH v6 09/23] target/riscv: Implement AIA local interrupt priorities

From: Anup Patel <anup@brainfault.org>
To: Peter Maydell <peter.maydell@linaro.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: qemu-riscv@nongnu.org, Anup Patel <anup@brainfault.org>,
	qemu-devel@nongnu.org,
	Alistair Francis <alistair.francis@wdc.com>,
	Atish Patra <atishp@atishpatra.org>,
	Bin Meng <bmeng.cn@gmail.com>
Subject: [PATCH v6 09/23] target/riscv: Implement AIA local interrupt priorities
Date: Thu, 30 Dec 2021 18:05:25 +0530	[thread overview]
Message-ID: <20211230123539.52786-10-anup@brainfault.org> (raw)
In-Reply-To: <20211230123539.52786-1-anup@brainfault.org>

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

The AIA spec defines programmable 8-bit priority for each local interrupt
at M-level, S-level and VS-level so we extend local interrupt processing
to consider AIA interrupt priorities. The AIA CSRs which help software
configure local interrupt priorities will be added by subsequent patches.

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>
---
 target/riscv/cpu.c        |  19 ++++
 target/riscv/cpu.h        |  12 ++
 target/riscv/cpu_helper.c | 231 ++++++++++++++++++++++++++++++++++----
 target/riscv/machine.c    |   3 +
 4 files changed, 244 insertions(+), 21 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 9f1a4d1088..9ad26035e1 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -348,6 +348,10 @@ void restore_state_to_opc(CPURISCVState *env, TranslationBlock *tb,
 
 static void riscv_cpu_reset(DeviceState *dev)
 {
+#ifndef CONFIG_USER_ONLY
+    uint8_t iprio;
+    int i, irq, rdzero;
+#endif
     CPUState *cs = CPU(dev);
     RISCVCPU *cpu = RISCV_CPU(cs);
     RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(cpu);
@@ -370,6 +374,21 @@ static void riscv_cpu_reset(DeviceState *dev)
     env->miclaim = MIP_SGEIP;
     env->pc = env->resetvec;
     env->two_stage_lookup = false;
+
+    /* Initialized default priorities of local interrupts. */
+    for (i = 0; i < ARRAY_SIZE(env->miprio); i++) {
+        iprio = riscv_cpu_default_priority(i);
+        env->miprio[i] = (i == IRQ_M_EXT) ? 0 : iprio;
+        env->siprio[i] = (i == IRQ_S_EXT) ? 0 : iprio;
+        env->hviprio[i] = 0;
+    }
+    i = 0;
+    while (!riscv_cpu_hviprio_index2irq(i, &irq, &rdzero)) {
+        if (!rdzero) {
+            env->hviprio[irq] = env->miprio[irq];
+        }
+        i++;
+    }
     /* mmte is supposed to have pm.current hardwired to 1 */
     env->mmte |= (PM_EXT_INITIAL | MMTE_M_PM_CURRENT);
 #endif
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 02f3ef2c3c..140fabfdf9 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -182,6 +182,10 @@ struct CPURISCVState {
     target_ulong mcause;
     target_ulong mtval;  /* since: priv-1.10.0 */
 
+    /* Machine and Supervisor interrupt priorities */
+    uint8_t miprio[64];
+    uint8_t siprio[64];
+
     /* Hypervisor CSRs */
     target_ulong hstatus;
     target_ulong hedeleg;
@@ -194,6 +198,9 @@ struct CPURISCVState {
     target_ulong hgeip;
     uint64_t htimedelta;
 
+    /* Hypervisor controlled virtual interrupt priorities */
+    uint8_t hviprio[64];
+
     /* Virtual CSRs */
     /*
      * For RV32 this is 32-bit vsstatus and 32-bit vsstatush.
@@ -379,6 +386,11 @@ int riscv_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
                                int cpuid, void *opaque);
 int riscv_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int riscv_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
+int riscv_cpu_hviprio_index2irq(int index, int *out_irq, int *out_rdzero);
+uint8_t riscv_cpu_default_priority(int irq);
+int riscv_cpu_mirq_pending(CPURISCVState *env);
+int riscv_cpu_sirq_pending(CPURISCVState *env);
+int riscv_cpu_vsirq_pending(CPURISCVState *env);
 bool riscv_cpu_fp_enabled(CPURISCVState *env);
 target_ulong riscv_cpu_get_geilen(CPURISCVState *env);
 void riscv_cpu_set_geilen(CPURISCVState *env, target_ulong geilen);
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index f94a36fa89..e3532de4cf 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -151,36 +151,225 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, target_ulong *pc,
 }
 
 #ifndef CONFIG_USER_ONLY
-static int riscv_cpu_local_irq_pending(CPURISCVState *env)
+
+/*
+ * The HS-mode is allowed to configure priority only for the
+ * following VS-mode local interrupts:
+ *
+ * 0  (Reserved interrupt, reads as zero)
+ * 1  Supervisor software interrupt
+ * 4  (Reserved interrupt, reads as zero)
+ * 5  Supervisor timer interrupt
+ * 8  (Reserved interrupt, reads as zero)
+ * 13 (Reserved interrupt)
+ * 14 "
+ * 15 "
+ * 16 "
+ * 18 Debug/trace interrupt
+ * 20 (Reserved interrupt)
+ * 22 "
+ * 24 "
+ * 26 "
+ * 28 "
+ * 30 (Reserved for standard reporting of bus or system errors)
+ */
+
+static int hviprio_index2irq[] =
+    { 0, 1, 4, 5, 8, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 30 };
+static int hviprio_index2rdzero[] =
+    { 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+
+int riscv_cpu_hviprio_index2irq(int index, int *out_irq, int *out_rdzero)
 {
-    target_ulong virt_enabled = riscv_cpu_virt_enabled(env);
+    if (index < 0 || ARRAY_SIZE(hviprio_index2irq) <= index) {
+        return -EINVAL;
+    }
+
+    if (out_irq) {
+        *out_irq = hviprio_index2irq[index];
+    }
 
-    target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
-    target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
+    if (out_rdzero) {
+        *out_rdzero = hviprio_index2rdzero[index];
+    }
 
-    target_ulong vsgemask =
-                (target_ulong)1 << get_field(env->hstatus, HSTATUS_VGEIN);
-    target_ulong vsgein = (env->hgeip & vsgemask) ? MIP_VSEIP : 0;
+    return 0;
+}
 
-    target_ulong pending = (env->mip | vsgein) & env->mie;
+uint8_t riscv_cpu_default_priority(int irq)
+{
+    int u, l;
+    uint8_t iprio = IPRIO_MMAXIPRIO;
 
-    target_ulong mie    = env->priv < PRV_M ||
-                          (env->priv == PRV_M && mstatus_mie);
-    target_ulong sie    = env->priv < PRV_S ||
-                          (env->priv == PRV_S && mstatus_sie);
-    target_ulong hsie   = virt_enabled || sie;
-    target_ulong vsie   = virt_enabled && sie;
+    if (irq < 0 || irq > 63) {
+        return iprio;
+    }
 
-    target_ulong irqs =
-            (pending & ~env->mideleg & -mie) |
-            (pending &  env->mideleg & ~env->hideleg & -hsie) |
-            (pending &  env->mideleg &  env->hideleg & -vsie);
+    /*
+     * Default priorities of local interrupts are defined in the
+     * RISC-V Advanced Interrupt Architecture specification.
+     *
+     * ----------------------------------------------------------------
+     *  Default  |
+     *  Priority | Major Interrupt Numbers
+     * ----------------------------------------------------------------
+     *  Highest  | 63 (3f), 62 (3e), 31 (1f), 30 (1e), 61 (3d), 60 (3c),
+     *           | 59 (3b), 58 (3a), 29 (1d), 28 (1c), 57 (39), 56 (38),
+     *           | 55 (37), 54 (36), 27 (1b), 26 (1a), 53 (35), 52 (34),
+     *           | 51 (33), 50 (32), 25 (19), 24 (18), 49 (31), 48 (30)
+     *           |
+     *           | 11 (0b),  3 (03),  7 (07)
+     *           |  9 (09),  1 (01),  5 (05)
+     *           | 12 (0c)
+     *           | 10 (0a),  2 (02),  6 (06)
+     *           |
+     *           | 47 (2f), 46 (2e), 23 (17), 22 (16), 45 (2d), 44 (2c),
+     *           | 43 (2b), 42 (2a), 21 (15), 20 (14), 41 (29), 40 (28),
+     *           | 39 (27), 38 (26), 19 (13), 18 (12), 37 (25), 36 (24),
+     *  Lowest   | 35 (23), 34 (22), 17 (11), 16 (10), 33 (21), 32 (20)
+     * ----------------------------------------------------------------
+     */
 
-    if (irqs) {
-        return ctz64(irqs); /* since non-zero */
+    u = IPRIO_DEFAULT_U(irq);
+    l = IPRIO_DEFAULT_L(irq);
+    if (u == 0) {
+        if (irq == IRQ_VS_EXT || irq == IRQ_VS_TIMER ||
+            irq == IRQ_VS_SOFT) {
+            iprio = IPRIO_DEFAULT_VS;
+        } else if (irq == IRQ_S_GEXT) {
+            iprio = IPRIO_DEFAULT_SGEXT;
+        } else if (irq == IRQ_S_EXT || irq == IRQ_S_TIMER ||
+                   irq == IRQ_S_SOFT) {
+            iprio = IPRIO_DEFAULT_S;
+        } else if (irq == IRQ_M_EXT || irq == IRQ_M_TIMER ||
+                   irq == IRQ_M_SOFT) {
+            iprio = IPRIO_DEFAULT_M;
+        } else {
+            iprio = IPRIO_DEFAULT_VS;
+        }
+    } else if (u == 1) {
+        if (l < 8) {
+            iprio = IPRIO_DEFAULT_16_23(irq);
+        } else {
+            iprio = IPRIO_DEFAULT_24_31(irq);
+        }
+    } else if (u == 2) {
+        iprio = IPRIO_DEFAULT_32_47(irq);
+    } else if (u == 3) {
+        iprio = IPRIO_DEFAULT_48_63(irq);
+    }
+
+    return iprio;
+}
+
+static int riscv_cpu_pending_to_irq(CPURISCVState *env,
+                                    uint64_t pending, uint8_t *iprio)
+{
+    int irq, best_irq = RISCV_EXCP_NONE;
+    unsigned int prio, best_prio = UINT_MAX;
+
+    if (!pending) {
+        return RISCV_EXCP_NONE;
+    }
+
+    irq = ctz64(pending);
+    if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
+        return irq;
+    }
+
+    pending = pending >> irq;
+    while (pending) {
+        prio = iprio[irq];
+        if (!prio) {
+            prio = (riscv_cpu_default_priority(irq) < IPRIO_DEFAULT_M) ?
+                   1 : IPRIO_MMAXIPRIO;
+        }
+        if ((pending & 0x1) && (prio < best_prio)) {
+            best_irq = irq;
+            best_prio = prio;
+        }
+        irq++;
+        pending = pending >> 1;
+    }
+
+    return best_irq;
+}
+
+static uint64_t riscv_cpu_all_pending(CPURISCVState *env)
+{
+    uint32_t gein = get_field(env->hstatus, HSTATUS_VGEIN);
+    uint64_t vsgein = (env->hgeip & (1ULL << gein)) ? MIP_VSEIP : 0;
+
+    return (env->mip | vsgein) & env->mie;
+}
+
+int riscv_cpu_mirq_pending(CPURISCVState *env)
+{
+    uint64_t irqs = riscv_cpu_all_pending(env) & ~env->mideleg &
+                    ~(MIP_SGEIP | MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
+
+    return riscv_cpu_pending_to_irq(env, irqs, env->miprio);
+}
+
+int riscv_cpu_sirq_pending(CPURISCVState *env)
+{
+    uint64_t irqs = riscv_cpu_all_pending(env) & env->mideleg &
+                    ~(MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
+
+    return riscv_cpu_pending_to_irq(env, irqs, env->siprio);
+}
+
+int riscv_cpu_vsirq_pending(CPURISCVState *env)
+{
+    uint64_t irqs = riscv_cpu_all_pending(env) & env->mideleg &
+                    (MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
+
+    return riscv_cpu_pending_to_irq(env, irqs >> 1, env->hviprio);
+}
+
+static int riscv_cpu_local_irq_pending(CPURISCVState *env)
+{
+    int virq;
+    uint64_t irqs, pending, mie, hsie, vsie;
+
+    /* Determine interrupt enable state of all privilege modes */
+    if (riscv_cpu_virt_enabled(env)) {
+        mie = 1;
+        hsie = 1;
+        vsie = (env->priv < PRV_S) ||
+               (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_SIE));
     } else {
-        return RISCV_EXCP_NONE; /* indicates no pending interrupt */
+        mie = (env->priv < PRV_M) ||
+              (env->priv == PRV_M && get_field(env->mstatus, MSTATUS_MIE));
+        hsie = (env->priv < PRV_S) ||
+               (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_SIE));
+        vsie = 0;
     }
+
+    /* Determine all pending interrupts */
+    pending = riscv_cpu_all_pending(env);
+
+    /* Check M-mode interrupts */
+    irqs = pending & ~env->mideleg & -mie;
+    if (irqs) {
+        return riscv_cpu_pending_to_irq(env, irqs, env->miprio);
+    }
+
+    /* Check HS-mode interrupts */
+    irqs = pending & env->mideleg & ~env->hideleg & -hsie;
+    if (irqs) {
+        return riscv_cpu_pending_to_irq(env, irqs, env->siprio);
+    }
+
+    /* Check VS-mode interrupts */
+    irqs = pending & env->mideleg & env->hideleg & -vsie;
+    if (irqs) {
+        virq = riscv_cpu_pending_to_irq(env, irqs >> 1, env->hviprio);
+        return (virq <= 0) ? virq : virq + 1;
+    }
+
+    /* Indicate no pending interrupt */
+    return RISCV_EXCP_NONE;
 }
 
 bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index 76dd0d415c..cffc444969 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -92,6 +92,7 @@ static const VMStateDescription vmstate_hyper = {
         VMSTATE_UINTTL(env.hgeie, RISCVCPU),
         VMSTATE_UINTTL(env.hgeip, RISCVCPU),
         VMSTATE_UINT64(env.htimedelta, RISCVCPU),
+        VMSTATE_UINT8_ARRAY(env.hviprio, RISCVCPU, 64),
 
         VMSTATE_UINT64(env.vsstatus, RISCVCPU),
         VMSTATE_UINTTL(env.vstvec, RISCVCPU),
@@ -173,6 +174,8 @@ const VMStateDescription vmstate_riscv_cpu = {
     .fields = (VMStateField[]) {
         VMSTATE_UINTTL_ARRAY(env.gpr, RISCVCPU, 32),
         VMSTATE_UINT64_ARRAY(env.fpr, RISCVCPU, 32),
+        VMSTATE_UINT8_ARRAY(env.miprio, RISCVCPU, 64),
+        VMSTATE_UINT8_ARRAY(env.siprio, RISCVCPU, 64),
         VMSTATE_UINTTL(env.pc, RISCVCPU),
         VMSTATE_UINTTL(env.load_res, RISCVCPU),
         VMSTATE_UINTTL(env.load_val, RISCVCPU),
-- 
2.25.1


