hw/riscv/virt-acpi-build: Fix RINTC PLIC context ID for KVM

Each RISC-V MADT RINTC entry contains an External Interrupt Controller
ID field. On the virt machine without AIA, this field identifies the
S-mode PLIC context associated with the hart.

TCG virt has both M-mode and S-mode PLIC contexts, so the S-mode context
ID is odd and 2 * local_cpu_id + 1 is correct. KVM virt exposes only
S-mode PLIC contexts, and those contexts are numbered contiguously from
0. Reporting the TCG context ID for KVM makes the guest enable a
different PLIC context from the one used by QEMU.

With ACPI enabled, this can leave PCI INTx interrupts pending in QEMU
while the guest-programmed PLIC context remains disabled. A virtio-blk
root disk can then stall during boot because its first interrupt is never
delivered.

Use local_cpu_id for KVM and keep the existing odd S-mode context ID for
TCG.

Fixes: d641da6ed4 ("hw/riscv/virt-acpi-build.c: Add PLIC in MADT")
Signed-off-by: Qingwei Hu <qingwei.hu@bytedance.com>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Message-ID: <20260604120017.398890-1-qingwei.hu@bytedance.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/riscv/virt-acpi-build.c

@@ -100,6 +100,8 @@ static void riscv_acpi_madt_add_rintc(uint32_t uid,
         build_append_int_noprefix(entry,
                                   ACPI_BUILD_INTC_ID(
                                       arch_ids->cpus[uid].props.node_id,
+                                      kvm_enabled() ?
+                                      local_cpu_id :
                                       2 * local_cpu_id + 1),
                                   4);
     } else {