[07/11,v2] target/riscv: Update CSR xnxti in CLIC mode

Commit Message

Ian Brockbank Aug. 19, 2024, 4:02 p.m. UTC

From: Ian Brockbank <[e-mail]>

The CSR can be used by software to service the next horizontal interrupt
when it has greater level than the saved interrupt context
(held in xcause`.pil`) and greater level than the interrupt threshold of
the corresponding privilege mode,

Signed-off-by: LIU Zhiwei <[e-mail]>
Signed-off-by: Ian Brockbank <[e-mail]>
---
 target/riscv/cpu_bits.h |  25 +++++++++
 target/riscv/csr.c      | 111 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)

--
2.46.0.windows.1
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Patch

diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 279a6f889b..3744b34504 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -166,6 +166,7 @@ 
 #define CSR_MCAUSE          0x342
 #define CSR_MTVAL           0x343
 #define CSR_MIP             0x344
+#define CSR_MNXTI           0x345 /* clic-spec-draft */
 #define CSR_MINTSTATUS      0xfb1 /* clic-spec-draft */
 #define CSR_MINTTHRESH      0x347 /* clic-spec-draft */

@@ -210,6 +211,7 @@ 
 #define CSR_SCAUSE          0x142
 #define CSR_STVAL           0x143
 #define CSR_SIP             0x144
+#define CSR_SNXTI           0x145 /* clic-spec-draft */
 #define CSR_SINTSTATUS      0xdb1 /* clic-spec-draft */
 #define CSR_SINTTHRESH      0x147 /* clic-spec-draft */

@@ -561,6 +563,8 @@ 
 #define MSTATUS_GVA         0x4000000000ULL
 #define MSTATUS_MPV         0x8000000000ULL

+#define MSTATUS_WRITE_MASK  0x0000001f
+
 #define MSTATUS64_UXL       0x0000000300000000ULL
 #define MSTATUS64_SXL       0x0000000C00000000ULL

@@ -754,6 +758,27 @@  typedef enum RISCVException {
 #define SINTSTATUS_SIL                     0x0000ff00 /* sil[15:8] */
 #define SINTSTATUS_UIL                     0x000000ff /* uil[7:0] */

+/* mcause */
+#define MCAUSE_INT                         (1 << (TARGET_LONG_BITS - 1))
+#define MCAUSE_MINHV                       0x40000000 /* minhv */
+#define MCAUSE_MPP                         0x30000000 /* mpp[1:0] */
+#define MCAUSE_MPIE                        0x08000000 /* mpie */
+#define MCAUSE_MPIL                        0x00ff0000 /* mpil[7:0] */
+#define MCAUSE_EXCCODE                     0x00000fff /* exccode[11:0] */
+
+/* scause */
+#define SCAUSE_INT                         (1 << (TARGET_LONG_BITS - 1))
+#define SCAUSE_SINHV                       0x40000000 /* sinhv */
+#define SCAUSE_SPP                         0x10000000 /* spp */
+#define SCAUSE_SPIE                        0x08000000 /* spie */
+#define SCAUSE_SPIL                        0x00ff0000 /* spil[7:0] */
+#define SCAUSE_EXCCODE                     0x00000fff /* exccode[11:0] */
+
+/* mcause & scause */
+#define XCAUSE_XPP_SHIFT                   28
+#define XCAUSE_XPIE_SHIFT                  27
+#define XCAUSE_XPIL_SHIFT                  16
+
 /* mtvec & stvec */
 #define XTVEC_MODE                         0x03
 #define XTVEC_SUBMODE                      0x3c
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index be0071fd25..813a5b927f 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -19,6 +19,7 @@ 

 #include "qemu/osdep.h"
 #include "qemu/log.h"
+#include "qemu/main-loop.h"
 #include "qemu/timer.h"
 #include "cpu.h"
 #include "tcg/tcg-cpu.h"
@@ -2936,6 +2937,77 @@  static RISCVException rmw_mviph(CPURISCVState *env, int csrno,
     return ret;
 }

+static bool get_xnxti_status(CPURISCVState *env)
+{
+    int clic_irq, clic_priv, clic_il, pil;
+
+    if (!env->exccode) { /* No interrupt */
+        return false;
+    }
+    /* The system is not in a CLIC mode */
+    if (!riscv_clic_is_clic_mode(env)) {
+        return false;
+    } else {
+        riscv_clic_decode_exccode(env->exccode, &clic_priv, &clic_il,
+                                  &clic_irq);
+
+        if (env->priv == PRV_M) {
+            pil = MAX(get_field(env->mcause, MCAUSE_MPIL), env->mintthresh);
+        } else if (env->priv == PRV_S) {
+            pil = MAX(get_field(env->scause, SCAUSE_SPIL), env->sintthresh);
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "CSR: rmw xnxti with unsupported mode\n");
+            exit(1);
+        }
+
+        if ((clic_priv != env->priv) || /* No horizontal interrupt */
+            (clic_il <= pil) || /* No higher level interrupt */
+            (riscv_clic_shv_interrupt(env->clic, clic_irq))) {
+            /* CLIC vector mode */
+            return false;
+        } else {
+            return true;
+        }
+    }
+}
+
+static int rmw_mnxti(CPURISCVState *env, int csrno, target_ulong *ret_value,
+                     target_ulong new_value, target_ulong write_mask)
+{
+    int clic_priv, clic_il, clic_irq;
+    bool ready;
+    if (write_mask) {
+        env->mstatus |= new_value & (write_mask & MSTATUS_WRITE_MASK);
+    }
+
+    BQL_LOCK_GUARD();
+
+    ready = get_xnxti_status(env);
+    if (ready) {
+        riscv_clic_decode_exccode(env->exccode, &clic_priv, &clic_il,
+                                  &clic_irq);
+        if (write_mask) {
+            bool edge = riscv_clic_edge_triggered(env->clic,  clic_irq);
+            if (edge) {
+                riscv_clic_clean_pending(env->clic, clic_irq);
+            }
+            env->mintstatus = set_field(env->mintstatus,
+                                        MINTSTATUS_MIL, clic_il);
+            env->mcause = set_field(env->mcause, MCAUSE_EXCCODE, clic_irq);
+        }
+        if (ret_value) {
+            *ret_value = (env->mtvt & ~0x3f) + sizeof(target_ulong) * clic_irq;
+        }
+    } else {
+        if (ret_value) {
+            *ret_value = 0;
+        }
+    }
+
+    return RISCV_EXCP_NONE;
+}
+
 static int read_mintstatus(CPURISCVState *env, int csrno, target_ulong *val)
 {
     *val = env->mintstatus;
@@ -3401,6 +3473,43 @@  static RISCVException rmw_siph(CPURISCVState *env, int csrno,
     return ret;
 }

+static int rmw_snxti(CPURISCVState *env, int csrno, target_ulong *ret_value,
+                     target_ulong new_value, target_ulong write_mask)
+{
+    int clic_priv, clic_il, clic_irq;
+    bool ready;
+    if (write_mask) {
+        env->mstatus |= new_value & (write_mask & MSTATUS_WRITE_MASK);
+    }
+
+    BQL_LOCK_GUARD();
+
+    ready = get_xnxti_status(env);
+    if (ready) {
+        riscv_clic_decode_exccode(env->exccode, &clic_priv, &clic_il,
+                                  &clic_irq);
+        if (write_mask) {
+            bool edge = riscv_clic_edge_triggered(env->clic, clic_irq);
+            if (edge) {
+                riscv_clic_clean_pending(env->clic, clic_irq);
+            }
+            /* update the PRV_S parts of mintstatus */
+            env->mintstatus = set_field(env->mintstatus,
+                                        MINTSTATUS_SIL, clic_il);
+            env->scause = set_field(env->scause, SCAUSE_EXCCODE, clic_irq);
+        }
+        if (ret_value) {
+            *ret_value = (env->stvt & ~0x3f) + sizeof(target_ulong) * clic_irq;
+        }
+    } else {
+        if (ret_value) {
+            *ret_value = 0;
+        }
+    }
+
+    return RISCV_EXCP_NONE;
+}
+
 static int read_sintstatus(CPURISCVState *env, int csrno, target_ulong *val)
 {
     /* sintstatus is a filtered view of mintstatus with the PRV_M removed */
@@ -5720,12 +5829,14 @@  riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {

     /* Machine Mode Core Level Interrupt Controller */
     [CSR_MTVT]           = { "mtvt",       clic,  read_mtvt, write_mtvt },
+    [CSR_MNXTI]          = { "mnxti",      clic,  NULL, NULL, rmw_mnxti },
     [CSR_MINTSTATUS]     = { "mintstatus", clic,  read_mintstatus       },
     [CSR_MINTTHRESH]     = { "mintthresh", clic,  read_mintthresh,
                              write_mintthresh },

     /* Supervisor Mode Core Level Interrupt Controller */
     [CSR_STVT]           = { "stvt",       clic,  read_stvt, write_stvt },
+    [CSR_SNXTI]          = { "snxti",      clic,  NULL, NULL, rmw_snxti },
     [CSR_SINTSTATUS]     = { "sintstatus", clic,  read_sintstatus       },
     [CSR_SINTTHRESH]     = { "sintthresh", clic,  read_sintthresh,
                              write_sintthresh },