hw/riscv/virt.c, riscv_aplic.c: add 'emulated_aplic' helpers

The current logic to determine if we don't need an emulated APLIC
controller, i.e. KVM will provide for us, is to determine if we're
running KVM, with in-kernel irqchip support, and running
aia=aplic-imsic. This is modelled by riscv_is_kvm_aia_aplic_imsic() and
virt_use_kvm_aia_aplic_imsic().

This won't suffice to support irqchip_split() mode: it will match
exactly the same conditions as the one above, but setting the irqchip to
'split' mode will now require us to emulate an APLIC s-mode controller,
like we're doing with 'aia=aplic'.

Create a new riscv_use_emulated_aplic() helper that will encapsulate
this logic. Replace the uses of "riscv_is_kvm_aia_aplic_imsic()" with
this helper every time we're taking a decision on emulate an APLIC
controller or not. Do the same in virt.c with virt_use_emulated_aplic().

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241119191706.718860-6-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/intc/riscv_aplic.c

@@ -32,6 +32,7 @@
 #include "target/riscv/cpu.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/kvm.h"
+#include "sysemu/tcg.h"
 #include "kvm/kvm_riscv.h"
 #include "migration/vmstate.h"
 
@@ -159,6 +160,23 @@ bool riscv_is_kvm_aia_aplic_imsic(bool msimode)
     return kvm_irqchip_in_kernel() && msimode;
 }
 
+bool riscv_use_emulated_aplic(bool msimode)
+{
+#ifdef CONFIG_KVM
+    if (tcg_enabled()) {
+        return true;
+    }
+
+    if (!riscv_is_kvm_aia_aplic_imsic(msimode)) {
+        return true;
+    }
+
+    return kvm_kernel_irqchip_split();
+#else
+    return true;
+#endif
+}
+
 static bool riscv_aplic_irq_rectified_val(RISCVAPLICState *aplic,
                                           uint32_t irq)
 {
@@ -857,7 +875,7 @@ static void riscv_aplic_realize(DeviceState *dev, Error **errp)
     uint32_t i;
     RISCVAPLICState *aplic = RISCV_APLIC(dev);
 
-    if (!riscv_is_kvm_aia_aplic_imsic(aplic->msimode)) {
+    if (riscv_use_emulated_aplic(aplic->msimode)) {
         aplic->bitfield_words = (aplic->num_irqs + 31) >> 5;
         aplic->sourcecfg = g_new0(uint32_t, aplic->num_irqs);
         aplic->state = g_new0(uint32_t, aplic->num_irqs);
@@ -881,7 +899,7 @@ static void riscv_aplic_realize(DeviceState *dev, Error **errp)
      * have IRQ lines delegated by their parent APLIC.
      */
     if (!aplic->parent) {
-        if (kvm_enabled() && riscv_is_kvm_aia_aplic_imsic(aplic->msimode)) {
+        if (kvm_enabled() && !riscv_use_emulated_aplic(aplic->msimode)) {
             qdev_init_gpio_in(dev, riscv_kvm_aplic_request, aplic->num_irqs);
         } else {
             qdev_init_gpio_in(dev, riscv_aplic_request, aplic->num_irqs);
@@ -1025,7 +1043,7 @@ DeviceState *riscv_aplic_create(hwaddr addr, hwaddr size,
 
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
 
-    if (!riscv_is_kvm_aia_aplic_imsic(msimode)) {
+    if (riscv_use_emulated_aplic(msimode)) {
         sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, addr);
     }
 

hw/riscv/virt.c

@@ -66,6 +66,13 @@ static bool virt_use_kvm_aia_aplic_imsic(RISCVVirtAIAType aia_type)
     return riscv_is_kvm_aia_aplic_imsic(msimode);
 }
 
+static bool virt_use_emulated_aplic(RISCVVirtAIAType aia_type)
+{
+    bool msimode = aia_type == VIRT_AIA_TYPE_APLIC_IMSIC;
+
+    return riscv_use_emulated_aplic(msimode);
+}
+
 static bool virt_aclint_allowed(void)
 {
     return tcg_enabled() || qtest_enabled();
@@ -779,8 +786,11 @@ static void create_fdt_sockets(RISCVVirtState *s, const MemMapEntry *memmap,
         *msi_pcie_phandle = msi_s_phandle;
     }
 
-    /* KVM AIA aplic-imsic only has one APLIC instance */
-    if (kvm_enabled() && virt_use_kvm_aia_aplic_imsic(s->aia_type)) {
+    /*
+     * With KVM AIA aplic-imsic, using an irqchip without split
+     * mode, we'll use only one APLIC instance.
+     */
+    if (!virt_use_emulated_aplic(s->aia_type)) {
         create_fdt_socket_aplic(s, memmap, 0,
                                 msi_m_phandle, msi_s_phandle, phandle,
                                 &intc_phandles[0], xplic_phandles,

include/hw/intc/riscv_aplic.h

@@ -72,6 +72,7 @@ struct RISCVAPLICState {
 
 void riscv_aplic_add_child(DeviceState *parent, DeviceState *child);
 bool riscv_is_kvm_aia_aplic_imsic(bool msimode);
+bool riscv_use_emulated_aplic(bool msimode);
 
 DeviceState *riscv_aplic_create(hwaddr addr, hwaddr size,
     uint32_t hartid_base, uint32_t num_harts, uint32_t num_sources,