hw/intc/imsic: refine the IMSIC realize

When the IMSIC is emulated in the kernel, the GPIO output lines to CPUs
and aia_ireg_rmw_fn setting can be remove. In this case the IMSIC
trigger CPU interrupts by KVM APIs, and the RMW of IREG is handled in
kernel.

This patch also move the code that claim the CPU interrupts to the
beginning of IMSIC realization. This can avoid the unnecessary resource
allocation before checking failed.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20250224025722.3999-2-yongxuan.wang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 26 insertions, 21 deletions

diff --git a/hw/intc/riscv_imsic.c b/hw/intc/riscv_imsic.c
index dc8162c0a7..241b12fef0 100644
--- a/hw/intc/riscv_imsic.c
+++ b/hw/intc/riscv_imsic.c
@@ -349,7 +349,19 @@ static void riscv_imsic_realize(DeviceState *dev, Error **errp)
     CPUState *cpu = cpu_by_arch_id(imsic->hartid);
     CPURISCVState *env = cpu ? cpu_env(cpu) : NULL;
 
+    /* Claim the CPU interrupt to be triggered by this IMSIC */
+    if (riscv_cpu_claim_interrupts(rcpu,
+            (imsic->mmode) ? MIP_MEIP : MIP_SEIP) < 0) {
+        error_setg(errp, "%s already claimed",
+                   (imsic->mmode) ? "MEIP" : "SEIP");
+        return;
+    }
+
     if (!kvm_irqchip_in_kernel()) {
+        /* Create output IRQ lines */
+        imsic->external_irqs = g_malloc(sizeof(qemu_irq) * imsic->num_pages);
+        qdev_init_gpio_out(dev, imsic->external_irqs, imsic->num_pages);
+
         imsic->num_eistate = imsic->num_pages * imsic->num_irqs;
         imsic->eidelivery = g_new0(uint32_t, imsic->num_pages);
         imsic->eithreshold = g_new0(uint32_t, imsic->num_pages);
@@ -361,18 +373,6 @@ static void riscv_imsic_realize(DeviceState *dev, Error **errp)
                           IMSIC_MMIO_SIZE(imsic->num_pages));
     sysbus_init_mmio(SYS_BUS_DEVICE(dev), &imsic->mmio);
 
-    /* Claim the CPU interrupt to be triggered by this IMSIC */
-    if (riscv_cpu_claim_interrupts(rcpu,
-            (imsic->mmode) ? MIP_MEIP : MIP_SEIP) < 0) {
-        error_setg(errp, "%s already claimed",
-                   (imsic->mmode) ? "MEIP" : "SEIP");
-        return;
-    }
-
-    /* Create output IRQ lines */
-    imsic->external_irqs = g_malloc(sizeof(qemu_irq) * imsic->num_pages);
-    qdev_init_gpio_out(dev, imsic->external_irqs, imsic->num_pages);
-
     /* Force select AIA feature and setup CSR read-modify-write callback */
     if (env) {
         if (!imsic->mmode) {
@@ -381,8 +381,11 @@ static void riscv_imsic_realize(DeviceState *dev, Error **errp)
         } else {
             rcpu->cfg.ext_smaia = true;
         }
-        riscv_cpu_set_aia_ireg_rmw_fn(env, (imsic->mmode) ? PRV_M : PRV_S,
-                                      riscv_imsic_rmw, imsic);
+
+        if (!kvm_irqchip_in_kernel()) {
+            riscv_cpu_set_aia_ireg_rmw_fn(env, (imsic->mmode) ? PRV_M : PRV_S,
+                                          riscv_imsic_rmw, imsic);
+        }
     }
 
     msi_nonbroken = true;
@@ -464,15 +467,17 @@ DeviceState *riscv_imsic_create(hwaddr addr, uint32_t hartid, bool mmode,
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, addr);
 
-    for (i = 0; i < num_pages; i++) {
-        if (!i) {
-            qdev_connect_gpio_out_named(dev, NULL, i,
-                                        qdev_get_gpio_in(DEVICE(cpu),
+    if (!kvm_irqchip_in_kernel()) {
+        for (i = 0; i < num_pages; i++) {
+            if (!i) {
+                qdev_connect_gpio_out_named(dev, NULL, i,
+                                            qdev_get_gpio_in(DEVICE(cpu),
                                             (mmode) ? IRQ_M_EXT : IRQ_S_EXT));
-        } else {
-            qdev_connect_gpio_out_named(dev, NULL, i,
-                                        qdev_get_gpio_in(DEVICE(cpu),
+            } else {
+                qdev_connect_gpio_out_named(dev, NULL, i,
+                                            qdev_get_gpio_in(DEVICE(cpu),
                                             IRQ_LOCAL_MAX + i - 1));
+            }
         }
     }