RE: [PATCH 2/4] hw/riscv: spike: Allow creating multiple sockets

[Anup Patel <Anup.Patel@wdc.com>]

> -----Original Message-----
> From: Palmer Dabbelt <palmer@dabbelt.com>
> Sent: 22 May 2020 01:46
> To: Anup Patel <Anup.Patel@wdc.com>
> Cc: Peter Maydell <peter.maydell@linaro.org>; Alistair Francis
> <Alistair.Francis@wdc.com>; sagark@eecs.berkeley.edu; Atish Patra
> <Atish.Patra@wdc.com>; anup@brainfault.org; qemu-riscv@nongnu.org;
> qemu-devel@nongnu.org; Anup Patel <Anup.Patel@wdc.com>
> Subject: Re: [PATCH 2/4] hw/riscv: spike: Allow creating multiple sockets
> 
> On Fri, 15 May 2020 23:37:44 PDT (-0700), Anup Patel wrote:
> > We extend RISC-V spike machine to allow creating a multi-socket machine.
> > Each RISC-V spike machine socket is a set of HARTs and a CLINT instance.
> > Other peripherals are shared between all RISC-V spike machine sockets.
> > We also update RISC-V spike machine device tree to treat each socket
> > as a NUMA node.
> >
> > The number of sockets in RISC-V spike machine can be specified using
> > the "sockets=" sub-option of QEMU "-smp" command-line option. By
> > default, only one socket RISC-V spike machine will be created.
> >
> > Currently, we only allow creating upto maximum 4 sockets with minimum
> > 2 HARTs per socket. In future, this limits can be changed.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > ---
> >  hw/riscv/spike.c         | 206 ++++++++++++++++++++++++---------------
> >  include/hw/riscv/spike.h |   8 +-
> >  2 files changed, 133 insertions(+), 81 deletions(-)
> >
> > diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c index
> > d5e0103d89..f63c57a87c 100644
> > --- a/hw/riscv/spike.c
> > +++ b/hw/riscv/spike.c
> > @@ -64,9 +64,11 @@ static void create_fdt(SpikeState *s, const struct
> MemmapEntry *memmap,
> >      uint64_t mem_size, const char *cmdline)  {
> >      void *fdt;
> > -    int cpu;
> > -    uint32_t *cells;
> > -    char *nodename;
> > +    int cpu, socket;
> > +    uint32_t *clint_cells;
> > +    unsigned long clint_addr;
> > +    uint32_t cpu_phandle, intc_phandle, phandle = 1;
> > +    char *name, *clint_name, *clust_name, *core_name, *cpu_name,
> > + *intc_name;
> >
> >      fdt = s->fdt = create_device_tree(&s->fdt_size);
> >      if (!fdt) {
> > @@ -88,68 +90,85 @@ static void create_fdt(SpikeState *s, const struct
> MemmapEntry *memmap,
> >      qemu_fdt_setprop_cell(fdt, "/soc", "#size-cells", 0x2);
> >      qemu_fdt_setprop_cell(fdt, "/soc", "#address-cells", 0x2);
> >
> > -    nodename = g_strdup_printf("/memory@%lx",
> > -        (long)memmap[SPIKE_DRAM].base);
> > -    qemu_fdt_add_subnode(fdt, nodename);
> > -    qemu_fdt_setprop_cells(fdt, nodename, "reg",
> > +    name = g_strdup_printf("/memory@%lx",
> (long)memmap[SPIKE_DRAM].base);
> > +    qemu_fdt_add_subnode(fdt, name);
> > +    qemu_fdt_setprop_cells(fdt, name, "reg",
> >          memmap[SPIKE_DRAM].base >> 32, memmap[SPIKE_DRAM].base,
> >          mem_size >> 32, mem_size);
> > -    qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
> > -    g_free(nodename);
> > +    qemu_fdt_setprop_string(fdt, name, "device_type", "memory");
> > +    g_free(name);
> >
> >      qemu_fdt_add_subnode(fdt, "/cpus");
> >      qemu_fdt_setprop_cell(fdt, "/cpus", "timebase-frequency",
> >          SIFIVE_CLINT_TIMEBASE_FREQ);
> >      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");
> >
> > -    for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {
> > -        nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
> > -        char *intc = g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
> > -        char *isa = riscv_isa_string(&s->soc.harts[cpu]);
> > -        qemu_fdt_add_subnode(fdt, nodename);
> > +    for (socket = (s->num_socs - 1); socket >= 0; socket--) {
> > +        clust_name = g_strdup_printf("/cpus/cpu-map/cluster0%d", socket);
> > +        qemu_fdt_add_subnode(fdt, clust_name);
> > +
> > +        clint_cells =  g_new0(uint32_t, s->soc[socket].num_harts *
> > + 4);
> > +
> > +        for (cpu = s->soc[socket].num_harts - 1; cpu >= 0; cpu--) {
> > +            cpu_phandle = phandle++;
> > +
> > +            cpu_name = g_strdup_printf("/cpus/cpu@%d",
> > +                s->soc[socket].hartid_base + cpu);
> > +            qemu_fdt_add_subnode(fdt, cpu_name);
> >  #if defined(TARGET_RISCV32)
> > -        qemu_fdt_setprop_string(fdt, nodename, "mmu-type", "riscv,sv32");
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "mmu-type",
> > + "riscv,sv32");
> >  #else
> > -        qemu_fdt_setprop_string(fdt, nodename, "mmu-type", "riscv,sv48");
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "mmu-type",
> > + "riscv,sv48");
> >  #endif
> > -        qemu_fdt_setprop_string(fdt, nodename, "riscv,isa", isa);
> > -        qemu_fdt_setprop_string(fdt, nodename, "compatible", "riscv");
> > -        qemu_fdt_setprop_string(fdt, nodename, "status", "okay");
> > -        qemu_fdt_setprop_cell(fdt, nodename, "reg", cpu);
> > -        qemu_fdt_setprop_string(fdt, nodename, "device_type", "cpu");
> > -        qemu_fdt_add_subnode(fdt, intc);
> > -        qemu_fdt_setprop_cell(fdt, intc, "phandle", 1);
> > -        qemu_fdt_setprop_string(fdt, intc, "compatible", "riscv,cpu-intc");
> > -        qemu_fdt_setprop(fdt, intc, "interrupt-controller", NULL, 0);
> > -        qemu_fdt_setprop_cell(fdt, intc, "#interrupt-cells", 1);
> > -        g_free(isa);
> > -        g_free(intc);
> > -        g_free(nodename);
> > -    }
> > +            name = riscv_isa_string(&s->soc[socket].harts[cpu]);
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "riscv,isa", name);
> > +            g_free(name);
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "compatible", "riscv");
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "status", "okay");
> > +            qemu_fdt_setprop_cell(fdt, cpu_name, "reg",
> > +                s->soc[socket].hartid_base + cpu);
> > +            qemu_fdt_setprop_string(fdt, cpu_name, "device_type", "cpu");
> > +            qemu_fdt_setprop_cell(fdt, cpu_name, "phandle",
> > + cpu_phandle);
> > +
> > +            intc_name = g_strdup_printf("%s/interrupt-controller", cpu_name);
> > +            qemu_fdt_add_subnode(fdt, intc_name);
> > +            intc_phandle = phandle++;
> > +            qemu_fdt_setprop_cell(fdt, intc_name, "phandle", intc_phandle);
> > +            qemu_fdt_setprop_string(fdt, intc_name, "compatible",
> > +                "riscv,cpu-intc");
> > +            qemu_fdt_setprop(fdt, intc_name, "interrupt-controller", NULL, 0);
> > +            qemu_fdt_setprop_cell(fdt, intc_name, "#interrupt-cells",
> > + 1);
> > +
> > +            clint_cells[cpu * 4 + 0] = cpu_to_be32(intc_phandle);
> > +            clint_cells[cpu * 4 + 1] = cpu_to_be32(IRQ_M_SOFT);
> > +            clint_cells[cpu * 4 + 2] = cpu_to_be32(intc_phandle);
> > +            clint_cells[cpu * 4 + 3] = cpu_to_be32(IRQ_M_TIMER);
> > +
> > +            core_name = g_strdup_printf("%s/core%d", clust_name, cpu);
> > +            qemu_fdt_add_subnode(fdt, core_name);
> > +            qemu_fdt_setprop_cell(fdt, core_name, "cpu",
> > + cpu_phandle);
> > +
> > +            g_free(core_name);
> > +            g_free(intc_name);
> > +            g_free(cpu_name);
> > +        }
> >
> > -    cells =  g_new0(uint32_t, s->soc.num_harts * 4);
> > -    for (cpu = 0; cpu < s->soc.num_harts; cpu++) {
> > -        nodename =
> > -            g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
> > -        uint32_t intc_phandle = qemu_fdt_get_phandle(fdt, nodename);
> > -        cells[cpu * 4 + 0] = cpu_to_be32(intc_phandle);
> > -        cells[cpu * 4 + 1] = cpu_to_be32(IRQ_M_SOFT);
> > -        cells[cpu * 4 + 2] = cpu_to_be32(intc_phandle);
> > -        cells[cpu * 4 + 3] = cpu_to_be32(IRQ_M_TIMER);
> > -        g_free(nodename);
> > +        clint_addr = memmap[SPIKE_CLINT].base +
> > +            (memmap[SPIKE_CLINT].size * socket);
> > +        clint_name = g_strdup_printf("/soc/clint@%lx", clint_addr);
> > +        qemu_fdt_add_subnode(fdt, clint_name);
> > +        qemu_fdt_setprop_string(fdt, clint_name, "compatible", "riscv,clint0");
> > +        qemu_fdt_setprop_cells(fdt, clint_name, "reg",
> > +            0x0, clint_addr, 0x0, memmap[SPIKE_CLINT].size);
> > +        qemu_fdt_setprop(fdt, clint_name, "interrupts-extended",
> > +            clint_cells, s->soc[socket].num_harts * sizeof(uint32_t)
> > + * 4);
> > +
> > +        g_free(clint_name);
> > +        g_free(clint_cells);
> > +        g_free(clust_name);
> >      }
> > -    nodename = g_strdup_printf("/soc/clint@%lx",
> > -        (long)memmap[SPIKE_CLINT].base);
> > -    qemu_fdt_add_subnode(fdt, nodename);
> > -    qemu_fdt_setprop_string(fdt, nodename, "compatible", "riscv,clint0");
> > -    qemu_fdt_setprop_cells(fdt, nodename, "reg",
> > -        0x0, memmap[SPIKE_CLINT].base,
> > -        0x0, memmap[SPIKE_CLINT].size);
> > -    qemu_fdt_setprop(fdt, nodename, "interrupts-extended",
> > -        cells, s->soc.num_harts * sizeof(uint32_t) * 4);
> > -    g_free(cells);
> > -    g_free(nodename);
> >
> >      if (cmdline) {
> >          qemu_fdt_add_subnode(fdt, "/chosen"); @@ -160,23 +179,51 @@
> > static void create_fdt(SpikeState *s, const struct MemmapEntry
> > *memmap,  static void spike_board_init(MachineState *machine)  {
> >      const struct MemmapEntry *memmap = spike_memmap;
> > -
> >      SpikeState *s = g_new0(SpikeState, 1);
> >      MemoryRegion *system_memory = get_system_memory();
> >      MemoryRegion *main_mem = g_new(MemoryRegion, 1);
> >      MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
> >      int i;
> > +    char *soc_name;
> >      unsigned int smp_cpus = machine->smp.cpus;
> > -
> > -    /* Initialize SOC */
> > -    object_initialize_child(OBJECT(machine), "soc", &s->soc, sizeof(s->soc),
> > -                            TYPE_RISCV_HART_ARRAY, &error_abort, NULL);
> > -    object_property_set_str(OBJECT(&s->soc), machine->cpu_type, "cpu-
> type",
> > -                            &error_abort);
> > -    object_property_set_int(OBJECT(&s->soc), smp_cpus, "num-harts",
> > -                            &error_abort);
> > -    object_property_set_bool(OBJECT(&s->soc), true, "realized",
> > -                            &error_abort);
> > +    unsigned int base_hartid, cpus_per_socket;
> > +
> > +    s->num_socs = machine->smp.sockets;
> > +
> > +    /* Ensure minumum required CPUs per socket */
> > +    if ((smp_cpus / s->num_socs) < SPIKE_CPUS_PER_SOCKET_MIN)
> > +        s->num_socs = 1;
> 
> Why?  It seems like creating single-hart sockets would be a good test case, and
> I'm pretty sure it's a configuration that we had in embedded systems.

Yes, single-hart sockets are sensible for testing software.

When "sockets=" sub-option is not provided in "-smp " command line
options, the machine->smp.sockets is set same as machine->smp.cpus
by smp_parse() function in hw/core/machine.c. This means by default
we will always get single-hart per socket. In other words, "-smp 4" will
be 4 cpus and 4 sockets. This is counter intuitive for users because when
"sockets=" is not provided we should default to single socket irrespective
to number of cpus.

I had added SPIKE_CPUS_PER_SOCKET_MIN to handle the default case
when no "sockets=" sub-option is provided.

Alternate approach will be: 
1. Add more members in struct CpuTopology of include/hw/boards.h
    to help us know whether "sockets=" option was passed or not
2. Update smp_parse() for new members in struct CpuTopology
3. Assume single-socket machine in QEMU RISC-V virt and QEMU
    RISC-V spike machines when "sockets=" option was not passed

Suggestions ??

> 
> > +    /* Limit the number of sockets */
> > +    if (SPIKE_SOCKETS_MAX < s->num_socs)
> > +        s->num_socs = SPIKE_SOCKETS_MAX;
> > +
> > +    /* Initialize socket */
> > +    for (i = 0; i < s->num_socs; i++) {
> > +        base_hartid = i * (smp_cpus / s->num_socs);
> > +        if (i == (s->num_socs - 1))
> > +            cpus_per_socket = smp_cpus - base_hartid;
> > +        else
> > +            cpus_per_socket = smp_cpus / s->num_socs;
> > +        soc_name = g_strdup_printf("soc%d", i);
> > +        object_initialize_child(OBJECT(machine), soc_name, &s->soc[i],
> > +            sizeof(s->soc[i]), TYPE_RISCV_HART_ARRAY, &error_abort, NULL);
> > +        g_free(soc_name);
> > +        object_property_set_str(OBJECT(&s->soc[i]),
> > +            machine->cpu_type, "cpu-type", &error_abort);
> > +        object_property_set_int(OBJECT(&s->soc[i]),
> > +            base_hartid, "hartid-base", &error_abort);
> > +        object_property_set_int(OBJECT(&s->soc[i]),
> > +            cpus_per_socket, "num-harts", &error_abort);
> > +        object_property_set_bool(OBJECT(&s->soc[i]),
> > +            true, "realized", &error_abort);
> > +
> > +        /* Core Local Interruptor (timer and IPI) for each socket */
> > +        sifive_clint_create(
> > +            memmap[SPIKE_CLINT].base + i * memmap[SPIKE_CLINT].size,
> > +            memmap[SPIKE_CLINT].size, base_hartid, cpus_per_socket,
> > +            SIFIVE_SIP_BASE, SIFIVE_TIMECMP_BASE, SIFIVE_TIME_BASE, false);
> > +    }
> >
> >      /* register system main memory (actual RAM) */
> >      memory_region_init_ram(main_mem, NULL, "riscv.spike.ram", @@
> > -249,12 +296,7 @@ static void spike_board_init(MachineState *machine)
> >                            &address_space_memory);
> >
> >      /* initialize HTIF using symbols found in load_kernel */
> > -    htif_mm_init(system_memory, mask_rom, &s->soc.harts[0].env,
> serial_hd(0));
> > -
> > -    /* Core Local Interruptor (timer and IPI) */
> > -    sifive_clint_create(memmap[SPIKE_CLINT].base,
> memmap[SPIKE_CLINT].size,
> > -        0, smp_cpus, SIFIVE_SIP_BASE, SIFIVE_TIMECMP_BASE,
> SIFIVE_TIME_BASE,
> > -        false);
> > +    htif_mm_init(system_memory, mask_rom, &s->soc[0].harts[0].env,
> > + serial_hd(0));
> >  }
> >
> >  static void spike_v1_10_0_board_init(MachineState *machine) @@ -268,6
> > +310,8 @@ static void spike_v1_10_0_board_init(MachineState *machine)
> >      int i;
> >      unsigned int smp_cpus = machine->smp.cpus;
> >
> > +    s->num_socs = 1;
> > +
> >      if (!qtest_enabled()) {
> >          info_report("The Spike v1.10.0 machine has been deprecated. "
> >                      "Please use the generic spike machine and specify the ISA "
> > @@ -275,13 +319,13 @@ static void
> spike_v1_10_0_board_init(MachineState *machine)
> >      }
> >
> >      /* Initialize SOC */
> > -    object_initialize_child(OBJECT(machine), "soc", &s->soc, sizeof(s->soc),
> > +    object_initialize_child(OBJECT(machine), "soc", &s->soc[0],
> > + sizeof(s->soc[0]),
> >                              TYPE_RISCV_HART_ARRAY, &error_abort, NULL);
> > -    object_property_set_str(OBJECT(&s->soc), SPIKE_V1_10_0_CPU, "cpu-
> type",
> > +    object_property_set_str(OBJECT(&s->soc[0]), SPIKE_V1_10_0_CPU,
> > + "cpu-type",
> >                              &error_abort);
> > -    object_property_set_int(OBJECT(&s->soc), smp_cpus, "num-harts",
> > +    object_property_set_int(OBJECT(&s->soc[0]), smp_cpus,
> > + "num-harts",
> >                              &error_abort);
> > -    object_property_set_bool(OBJECT(&s->soc), true, "realized",
> > +    object_property_set_bool(OBJECT(&s->soc[0]), true, "realized",
> >                              &error_abort);
> >
> >      /* register system main memory (actual RAM) */ @@ -339,7 +383,7
> > @@ static void spike_v1_10_0_board_init(MachineState *machine)
> >                            &address_space_memory);
> >
> >      /* initialize HTIF using symbols found in load_kernel */
> > -    htif_mm_init(system_memory, mask_rom, &s->soc.harts[0].env,
> serial_hd(0));
> > +    htif_mm_init(system_memory, mask_rom, &s->soc[0].harts[0].env,
> > + serial_hd(0));
> >
> >      /* Core Local Interruptor (timer and IPI) */
> >      sifive_clint_create(memmap[SPIKE_CLINT].base,
> > memmap[SPIKE_CLINT].size, @@ -358,6 +402,8 @@ static void
> spike_v1_09_1_board_init(MachineState *machine)
> >      int i;
> >      unsigned int smp_cpus = machine->smp.cpus;
> >
> > +    s->num_socs = 1;
> > +
> >      if (!qtest_enabled()) {
> >          info_report("The Spike v1.09.1 machine has been deprecated. "
> >                      "Please use the generic spike machine and specify the ISA "
> > @@ -365,13 +411,13 @@ static void
> spike_v1_09_1_board_init(MachineState *machine)
> >      }
> >
> >      /* Initialize SOC */
> > -    object_initialize_child(OBJECT(machine), "soc", &s->soc, sizeof(s->soc),
> > +    object_initialize_child(OBJECT(machine), "soc", &s->soc[0],
> > + sizeof(s->soc[0]),
> >                              TYPE_RISCV_HART_ARRAY, &error_abort, NULL);
> > -    object_property_set_str(OBJECT(&s->soc), SPIKE_V1_09_1_CPU, "cpu-
> type",
> > +    object_property_set_str(OBJECT(&s->soc[0]), SPIKE_V1_09_1_CPU,
> > + "cpu-type",
> >                              &error_abort);
> > -    object_property_set_int(OBJECT(&s->soc), smp_cpus, "num-harts",
> > +    object_property_set_int(OBJECT(&s->soc[0]), smp_cpus,
> > + "num-harts",
> >                              &error_abort);
> > -    object_property_set_bool(OBJECT(&s->soc), true, "realized",
> > +    object_property_set_bool(OBJECT(&s->soc[0]), true, "realized",
> >                              &error_abort);
> >
> >      /* register system main memory (actual RAM) */ @@ -425,7 +471,7
> > @@ static void spike_v1_09_1_board_init(MachineState *machine)
> >          "};\n";
> >
> >      /* build config string with supplied memory size */
> > -    char *isa = riscv_isa_string(&s->soc.harts[0]);
> > +    char *isa = riscv_isa_string(&s->soc[0].harts[0]);
> >      char *config_string = g_strdup_printf(config_string_tmpl,
> >          (uint64_t)memmap[SPIKE_CLINT].base + SIFIVE_TIME_BASE,
> >          (uint64_t)memmap[SPIKE_DRAM].base,
> > @@ -448,7 +494,7 @@ static void spike_v1_09_1_board_init(MachineState
> *machine)
> >                            &address_space_memory);
> >
> >      /* initialize HTIF using symbols found in load_kernel */
> > -    htif_mm_init(system_memory, mask_rom, &s->soc.harts[0].env,
> serial_hd(0));
> > +    htif_mm_init(system_memory, mask_rom, &s->soc[0].harts[0].env,
> > + serial_hd(0));
> >
> >      /* Core Local Interruptor (timer and IPI) */
> >      sifive_clint_create(memmap[SPIKE_CLINT].base,
> > memmap[SPIKE_CLINT].size, @@ -476,7 +522,7 @@ static void
> > spike_machine_init(MachineClass *mc)  {
> >      mc->desc = "RISC-V Spike Board";
> >      mc->init = spike_board_init;
> > -    mc->max_cpus = 8;
> > +    mc->max_cpus = SPIKE_CPUS_MAX;
> >      mc->is_default = true;
> >      mc->default_cpu_type = SPIKE_V1_10_0_CPU;  } diff --git
> > a/include/hw/riscv/spike.h b/include/hw/riscv/spike.h index
> > dc770421bc..04a9f593b5 100644
> > --- a/include/hw/riscv/spike.h
> > +++ b/include/hw/riscv/spike.h
> > @@ -22,12 +22,18 @@
> >  #include "hw/riscv/riscv_hart.h"
> >  #include "hw/sysbus.h"
> >
> > +#define SPIKE_SOCKETS_MAX 4
> > +#define SPIKE_CPUS_PER_SOCKET_MIN 2
> > +#define SPIKE_CPUS_PER_SOCKET_MAX 4
> > +#define SPIKE_CPUS_MAX (SPIKE_SOCKETS_MAX *
> > +SPIKE_CPUS_PER_SOCKET_MAX)
> > +
> >  typedef struct {
> >      /*< private >*/
> >      SysBusDevice parent_obj;
> >
> >      /*< public >*/
> > -    RISCVHartArrayState soc;
> > +    unsigned int num_socs;
> > +    RISCVHartArrayState soc[SPIKE_SOCKETS_MAX];
> >      void *fdt;
> >      int fdt_size;
> >  } SpikeState;

Regards,
Anup