The hart bit setting is different with Linux AIA driver[1] when the number of hart is power of 2. For example, when the guest has 4 harts, the estimated result of AIA driver is 2, whereas we pass 3 to RISC-V/KVM. Since only 2 bits are needed to represent 4 harts, update the formula to get the accurate result.
[1] https://lore.kernel.org/all/20240307140307.646078-1-apa...@ventanamicro.com/ Signed-off-by: Yong-Xuan Wang <yongxuan.w...@sifive.com> --- target/riscv/kvm/kvm-cpu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c index 6a6c6cae80f1..388c4ddaa145 100644 --- a/target/riscv/kvm/kvm-cpu.c +++ b/target/riscv/kvm/kvm-cpu.c @@ -1642,7 +1642,14 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift, } } - hart_bits = find_last_bit(&max_hart_per_socket, BITS_PER_LONG) + 1; + + if (max_hart_per_socket > 1) { + max_hart_per_socket--; + hart_bits = find_last_bit(&max_hart_per_socket, BITS_PER_LONG) + 1; + } else { + hart_bits = 0; + } + ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, KVM_DEV_RISCV_AIA_CONFIG_HART_BITS, &hart_bits, true, NULL); -- 2.17.1