Re: [PATCH v2 1/1] target/riscv/kvm: fix timebase-frequency when using KVM acceleration

[Alistair Francis]

On Thu, Mar 14, 2024 at 4:17 PM Yong-Xuan Wang <yongxuan.wang@sifive.com> wrote:
>
> The timebase-frequency of guest OS should be the same with host
> machine. The timebase-frequency value in DTS should be got from
> hypervisor when using KVM acceleration.
>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

>
> ---
> Changelog
> v2:
> - update the function definition
> - restructure if-else statement
> ---
>  hw/riscv/virt.c              | 2 ++
>  target/riscv/kvm/kvm-cpu.c   | 9 +++++++++
>  target/riscv/kvm/kvm_riscv.h | 1 +
>  3 files changed, 12 insertions(+)
>
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index a094af97c32a..533b17799581 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -711,6 +711,8 @@ static void create_fdt_sockets(RISCVVirtState *s, const 
> MemMapEntry *memmap,
>
>      qemu_fdt_add_subnode(ms->fdt, "/cpus");
>      qemu_fdt_setprop_cell(ms->fdt, "/cpus", "timebase-frequency",
> +                          kvm_enabled() ?
> +                          kvm_riscv_get_timebase_frequency(first_cpu) :
>                            RISCV_ACLINT_DEFAULT_TIMEBASE_FREQ);
>      qemu_fdt_setprop_cell(ms->fdt, "/cpus", "#size-cells", 0x0);
>      qemu_fdt_setprop_cell(ms->fdt, "/cpus", "#address-cells", 0x1);
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index c7afdb1e81b7..bbb115eaa867 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -739,6 +739,15 @@ static void kvm_riscv_put_regs_timer(CPUState *cs)
>      env->kvm_timer_dirty = false;
>  }
>
> +uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs)
> +{
> +    uint64_t reg;
> +
> +    KVM_RISCV_GET_TIMER(cs, frequency, reg);
> +
> +    return reg;
> +}
> +
>  static int kvm_riscv_get_regs_vector(CPUState *cs)
>  {
>      RISCVCPU *cpu = RISCV_CPU(cs);
> diff --git a/target/riscv/kvm/kvm_riscv.h b/target/riscv/kvm/kvm_riscv.h
> index 4bd98fddc776..58518988681d 100644
> --- a/target/riscv/kvm/kvm_riscv.h
> +++ b/target/riscv/kvm/kvm_riscv.h
> @@ -28,5 +28,6 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t 
> group_shift,
>  void riscv_kvm_aplic_request(void *opaque, int irq, int level);
>  int kvm_riscv_sync_mpstate_to_kvm(RISCVCPU *cpu, int state);
>  void riscv_kvm_cpu_finalize_features(RISCVCPU *cpu, Error **errp);
> +uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs);
>
>  #endif
> --
> 2.17.1
>
>