target/riscv/kvm: consider irqchip_split() in aia_create()

Before adding support to kernel-irqchip=split when using KVM AIA we need
to change how we create the in-kernel AIA device.

In the use case we have so far, i.e. in-kernel irqchip without split
mode, both the s-mode APLIC and IMSIC controllers are provided by the
irqchip. In irqchip_split() mode we'll emulate the s-mode APLIC
controller, which will send MSIs to the in-kernel IMSIC controller. To
do that we need to change kvm_riscv_aia_create() to not create the
in-kernel s-mode APLIC controller.

In the kernel source arch/riscv/kvm/aia_aplic.c, function
kvm_riscv_aia_aplic_init(), we verify that the APLIC controller won't be
instantiated by KVM if we do not set 'nr_sources', which is set via
KVM_DEV_RISCV_AIA_CONFIG_SRCS. For QEMU this means that we should not
set 'aia_irq_num' during kvm_riscv_aia_create() in irqchip_split() mode.

In this same condition, skip KVM_DEV_RISCV_AIA_ADDR_APLIC as well since
it is used to set the base address for the in-kernel APLIC controller.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241119191706.718860-5-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 23 insertions, 15 deletions

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index c53ca1f..a9680f2 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1734,13 +1734,29 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,
         }
     }
 
-    ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG,
-                            KVM_DEV_RISCV_AIA_CONFIG_SRCS,
-                            &aia_irq_num, true, NULL);
-    if (ret < 0) {
-        error_report("KVM AIA: failed to set number of input irq lines");
-        exit(1);
-    }
+    /*
+     * Skip APLIC creation in KVM if we're running split mode.
+     * This is done by leaving KVM_DEV_RISCV_AIA_CONFIG_SRCS
+     * unset. We can also skip KVM_DEV_RISCV_AIA_ADDR_APLIC
+     * since KVM won't be using it.
+     */
+    if (!kvm_kernel_irqchip_split()) {
+        ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG,
+                                KVM_DEV_RISCV_AIA_CONFIG_SRCS,
+                                &aia_irq_num, true, NULL);
+        if (ret < 0) {
+            error_report("KVM AIA: failed to set number of input irq lines");
+            exit(1);
+        }
+
+        ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_ADDR,
+                                KVM_DEV_RISCV_AIA_ADDR_APLIC,
+                                &aplic_base, true, NULL);
+        if (ret < 0) {
+            error_report("KVM AIA: failed to set the base address of APLIC");
+            exit(1);
+        }
+     }
 
     ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG,
                             KVM_DEV_RISCV_AIA_CONFIG_IDS,
@@ -1781,14 +1797,6 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,
         exit(1);
     }
 
-    ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_ADDR,
-                            KVM_DEV_RISCV_AIA_ADDR_APLIC,
-                            &aplic_base, true, NULL);
-    if (ret < 0) {
-        error_report("KVM AIA: failed to set the base address of APLIC");
-        exit(1);
-    }
-
     for (socket = 0; socket < socket_count; socket++) {
         socket_imsic_base = imsic_base + socket * (1U << group_shift);
         hart_count = riscv_socket_hart_count(machine, socket);