RE: [PATCH RFC v4 13/15] target/riscv: Introduce dynamic time frequency for virt machine

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> -----Original Message-----
> From: Alistair Francis [mailto:alistair23@xxxxxxxxx]
> Sent: Wednesday, December 9, 2020 6:26 AM
> To: Jiangyifei <jiangyifei@xxxxxxxxxx>
> Cc: qemu-devel@xxxxxxxxxx Developers <qemu-devel@xxxxxxxxxx>; open
> list:RISC-V <qemu-riscv@xxxxxxxxxx>; Zhangxiaofeng (F)
> <victor.zhangxiaofeng@xxxxxxxxxx>; Sagar Karandikar
> <sagark@xxxxxxxxxxxxxxxxx>; open list:Overall <kvm@xxxxxxxxxxxxxxx>;
> libvir-list@xxxxxxxxxx; Bastian Koppelmann
> <kbastian@xxxxxxxxxxxxxxxxxxxxx>; Anup Patel <anup.patel@xxxxxxx>;
> yinyipeng <yinyipeng1@xxxxxxxxxx>; Alistair Francis
> <Alistair.Francis@xxxxxxx>; kvm-riscv@xxxxxxxxxxxxxxxxxxx; Palmer Dabbelt
> <palmer@xxxxxxxxxxx>; dengkai (A) <dengkai1@xxxxxxxxxx>; Wubin (H)
> <wu.wubin@xxxxxxxxxx>; Zhanghailiang <zhang.zhanghailiang@xxxxxxxxxx>
> Subject: Re: [PATCH RFC v4 13/15] target/riscv: Introduce dynamic time
> frequency for virt machine
> 
> On Thu, Dec 3, 2020 at 4:57 AM Yifei Jiang <jiangyifei@xxxxxxxxxx> wrote:
> >
> > Currently, time base frequency was fixed as SIFIVE_CLINT_TIMEBASE_FREQ.
> > Here introduce "time-frequency" property to set time base frequency
> > dynamically of which default value is still
> > SIFIVE_CLINT_TIMEBASE_FREQ. The virt machine uses frequency of the first
> cpu to create clint and fdt.
> >
> > Signed-off-by: Yifei Jiang <jiangyifei@xxxxxxxxxx>
> > Signed-off-by: Yipeng Yin <yinyipeng1@xxxxxxxxxx>
> > ---
> >  hw/riscv/virt.c    | 18 ++++++++++++++----
> >  target/riscv/cpu.c |  3 +++
> >  target/riscv/cpu.h |  2 ++
> >  3 files changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c index
> > 47b7018193..788a7237b6 100644
> > --- a/hw/riscv/virt.c
> > +++ b/hw/riscv/virt.c
> > @@ -178,7 +178,7 @@ static void create_pcie_irq_map(void *fdt, char
> > *nodename,  }
> >
> >  static void create_fdt(RISCVVirtState *s, const struct MemmapEntry
> *memmap,
> > -    uint64_t mem_size, const char *cmdline)
> > +    uint64_t mem_size, const char *cmdline, uint64_t
> > + timebase_frequency)
> >  {
> >      void *fdt;
> >      int i, cpu, socket;
> > @@ -225,7 +225,7 @@ static void create_fdt(RISCVVirtState *s, const
> > struct MemmapEntry *memmap,
> >
> >      qemu_fdt_add_subnode(fdt, "/cpus");
> >      qemu_fdt_setprop_cell(fdt, "/cpus", "timebase-frequency",
> > -                          SIFIVE_CLINT_TIMEBASE_FREQ);
> > +                          timebase_frequency);
> >      qemu_fdt_setprop_cell(fdt, "/cpus", "#size-cells", 0x0);
> >      qemu_fdt_setprop_cell(fdt, "/cpus", "#address-cells", 0x1);
> >      qemu_fdt_add_subnode(fdt, "/cpus/cpu-map"); @@ -510,6 +510,7
> @@
> > static void virt_machine_init(MachineState *machine)
> >      target_ulong firmware_end_addr, kernel_start_addr;
> >      uint32_t fdt_load_addr;
> >      uint64_t kernel_entry;
> > +    uint64_t timebase_frequency = 0;
> >      DeviceState *mmio_plic, *virtio_plic, *pcie_plic;
> >      int i, j, base_hartid, hart_count;
> >      CPUState *cs;
> > @@ -553,12 +554,20 @@ static void virt_machine_init(MachineState
> *machine)
> >                                  hart_count, &error_abort);
> >          sysbus_realize(SYS_BUS_DEVICE(&s->soc[i]), &error_abort);
> >
> > +        if (!timebase_frequency) {
> > +            timebase_frequency = RISCV_CPU(first_cpu)->env.frequency;
> > +        }
> > +        /* If vcpu's time frequency is not specified, we use default
> frequency */
> > +        if (!timebase_frequency) {
> > +            timebase_frequency = SIFIVE_CLINT_TIMEBASE_FREQ;
> > +        }
> > +
> >          /* Per-socket CLINT */
> >          sifive_clint_create(
> >              memmap[VIRT_CLINT].base + i *
> memmap[VIRT_CLINT].size,
> >              memmap[VIRT_CLINT].size, base_hartid, hart_count,
> >              SIFIVE_SIP_BASE, SIFIVE_TIMECMP_BASE,
> SIFIVE_TIME_BASE,
> > -            SIFIVE_CLINT_TIMEBASE_FREQ, true);
> > +            timebase_frequency, true);
> >
> >          /* Per-socket PLIC hart topology configuration string */
> >          plic_hart_config_len =
> > @@ -610,7 +619,8 @@ static void virt_machine_init(MachineState
> *machine)
> >          main_mem);
> >
> >      /* create device tree */
> > -    create_fdt(s, memmap, machine->ram_size,
> machine->kernel_cmdline);
> > +    create_fdt(s, memmap, machine->ram_size,
> machine->kernel_cmdline,
> > +               timebase_frequency);
> >
> >      /* boot rom */
> >      memory_region_init_rom(mask_rom, NULL, "riscv_virt_board.mrom",
> > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index
> > 439dc89ee7..66f35bcbbf 100644
> > --- a/target/riscv/cpu.c
> > +++ b/target/riscv/cpu.c
> > @@ -494,6 +494,8 @@ static void riscv_cpu_realize(DeviceState *dev,
> > Error **errp)
> >
> >      riscv_cpu_register_gdb_regs_for_features(cs);
> >
> > +    env->user_frequency = env->frequency;
> > +
> >      qemu_init_vcpu(cs);
> >      cpu_reset(cs);
> >
> > @@ -531,6 +533,7 @@ static Property riscv_cpu_properties[] = {
> >      DEFINE_PROP_BOOL("mmu", RISCVCPU, cfg.mmu, true),
> >      DEFINE_PROP_BOOL("pmp", RISCVCPU, cfg.pmp, true),
> >      DEFINE_PROP_UINT64("resetvec", RISCVCPU, cfg.resetvec,
> > DEFAULT_RSTVEC),
> > +    DEFINE_PROP_UINT64("time-frequency", RISCVCPU, env.frequency, 0),
> 
> Why not set the default to SIFIVE_CLINT_TIMEBASE_FREQ?
> 

When the time frequency is not specified, it will follow the host or the migration
source. And we define 0 as equivalent to not specified time frequency.

> Also, QEMU now has a clock API, is using that instead a better option?
> 

Sorry, I didn't find the clock API. Could you tell me what the API is.
I think that the time frequency is option of KVM VCPU. So it is appropriate to put this
option in the CPU.

Yifei

> Alistair
> 
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> >
> > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index
> > 16d6050ead..f5b6c34176 100644
> > --- a/target/riscv/cpu.h
> > +++ b/target/riscv/cpu.h
> > @@ -243,6 +243,8 @@ struct CPURISCVState {
> >      uint64_t kvm_timer_time;
> >      uint64_t kvm_timer_compare;
> >      uint64_t kvm_timer_state;
> > +    uint64_t user_frequency;
> > +    uint64_t frequency;
> >  };
> >
> >  OBJECT_DECLARE_TYPE(RISCVCPU, RISCVCPUClass,
> > --
> > 2.19.1
> >
> >




[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux