Re: [PULL 65/76] hw/mips/loongson3_virt: Wire up loongson_ipi device

[Philippe Mathieu-Daudé]

Hi Jiaxun,

On 18/6/24 18:00, Philippe Mathieu-Daudé wrote:
> From: Jiaxun Yang <jiaxun.yang@flygoat.com>
>
> Wire up loongson_ipi device for loongson3_virt machine, so we
> can have SMP support for TCG backend as well.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Acked-by: Song Gao <gaosong@loongson.cn>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Message-ID: <20240605-loongson3-ipi-v3-3-ddd2c0e03fa3@flygoat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   hw/mips/loongson3_bootp.h |  3 +++
>   hw/mips/loongson3_bootp.c |  2 --
>   hw/mips/loongson3_virt.c  | 39 +++++++++++++++++++++++++++++++++++++--
>   hw/mips/Kconfig           |  1 +
>   4 files changed, 41 insertions(+), 4 deletions(-)


> diff --git a/hw/mips/loongson3_bootp.c b/hw/mips/loongson3_bootp.c
> index 03a10b63c1..b97b81903b 100644
> --- a/hw/mips/loongson3_bootp.c
> +++ b/hw/mips/loongson3_bootp.c
> @@ -25,8 +25,6 @@
>   #include "hw/boards.h"
>   #include "hw/mips/loongson3_bootp.h"
>   
> -#define LOONGSON3_CORE_PER_NODE 4
> -
>   static void init_cpu_info(void *g_cpuinfo, uint64_t cpu_freq)
>   {
>       struct efi_cpuinfo_loongson *c = g_cpuinfo;
> diff --git a/hw/mips/loongson3_virt.c b/hw/mips/loongson3_virt.c
> index 440268a074..4ad36f0c5b 100644
> --- a/hw/mips/loongson3_virt.c
> +++ b/hw/mips/loongson3_virt.c
> @@ -36,6 +36,7 @@
>   #include "hw/mips/loongson3_bootp.h"
>   #include "hw/misc/unimp.h"
>   #include "hw/intc/i8259.h"
> +#include "hw/intc/loongson_ipi.h"
>   #include "hw/loader.h"
>   #include "hw/isa/superio.h"
>   #include "hw/pci/msi.h"
> @@ -74,6 +75,7 @@ const MemMapEntry virt_memmap[] = {
>       [VIRT_PCIE_ECAM] =   { 0x1a000000,     0x2000000 },
>       [VIRT_BIOS_ROM] =    { 0x1fc00000,      0x200000 },
>       [VIRT_UART] =        { 0x1fe001e0,           0x8 },
> +    [VIRT_IPI] =         { 0x3ff01000,         0x400 },
>       [VIRT_LIOINTC] =     { 0x3ff01400,          0x64 },
>       [VIRT_PCIE_MMIO] =   { 0x40000000,    0x40000000 },
>       [VIRT_HIGHMEM] =     { 0x80000000,           0x0 }, /* Variable */
> @@ -485,6 +487,7 @@ static void mips_loongson3_virt_init(MachineState *machine)
>       Clock *cpuclk;
>       CPUMIPSState *env;
>       DeviceState *liointc;
> +    DeviceState *ipi = NULL;
>       char *filename;
>       const char *kernel_cmdline = machine->kernel_cmdline;
>       const char *kernel_filename = machine->kernel_filename;
> @@ -494,6 +497,7 @@ static void mips_loongson3_virt_init(MachineState *machine)
>       MemoryRegion *ram = g_new(MemoryRegion, 1);
>       MemoryRegion *bios = g_new(MemoryRegion, 1);
>       MemoryRegion *iomem = g_new(MemoryRegion, 1);
> +    MemoryRegion *iocsr = g_new(MemoryRegion, 1);
>   
>       /* TODO: TCG will support all CPU types */
>       if (!kvm_enabled()) {
> @@ -527,6 +531,19 @@ static void mips_loongson3_virt_init(MachineState *machine)
>       create_unimplemented_device("mmio fallback 0", 0x10000000, 256 * MiB);
>       create_unimplemented_device("mmio fallback 1", 0x30000000, 256 * MiB);
>   
> +    memory_region_init(iocsr, OBJECT(machine), "loongson3.iocsr", UINT32_MAX);
> +
> +    /* IPI controller is in kernel for KVM */
> +    if (!kvm_enabled()) {
> +        ipi = qdev_new(TYPE_LOONGSON_IPI);
> +        qdev_prop_set_uint32(ipi, "num-cpu", machine->smp.cpus);
> +        sysbus_realize_and_unref(SYS_BUS_DEVICE(ipi), &error_fatal);
> +        memory_region_add_subregion(iocsr, SMP_IPI_MAILBOX,
> +                                sysbus_mmio_get_region(SYS_BUS_DEVICE(ipi), 
> 0));
> +        memory_region_add_subregion(iocsr, MAIL_SEND_ADDR,
> +                                sysbus_mmio_get_region(SYS_BUS_DEVICE(ipi), 
> 1));
> +    }
> +
>       liointc = qdev_new("loongson.liointc");
>       sysbus_realize_and_unref(SYS_BUS_DEVICE(liointc), &error_fatal);
>   
> @@ -543,6 +560,8 @@ static void mips_loongson3_virt_init(MachineState *machine)
>       clock_set_hz(cpuclk, DEF_LOONGSON3_FREQ);
>   
>       for (i = 0; i < machine->smp.cpus; i++) {
> +        int node = i / LOONGSON3_CORE_PER_NODE;
> +        int core = i % LOONGSON3_CORE_PER_NODE;
>           int ip;
>   
>           /* init CPUs */
> @@ -553,12 +572,28 @@ static void mips_loongson3_virt_init(MachineState 
> *machine)
>           cpu_mips_clock_init(cpu);
>           qemu_register_reset(main_cpu_reset, cpu);
>   
> -        if (i >= 4) {
> +        if (ipi) {

Coverity mentions a  Null pointer dereference (REVERSE_INULL) here
(CID 1547264):

  Null-checking "ipi" suggests that it may be null, but it has
  already been dereferenced on all paths leading to the check.

Maybe this silences it:

 -        if (ipi) {
 +        if (!kvm_enabled()) {

Still I'd rather using tcg_enabled() in this file.

Do you mind posting a patch fixing it?

> +            hwaddr base = ((hwaddr)node << 44) + virt_memmap[VIRT_IPI].base;
> +            base += core * 0x100;
> +            qdev_connect_gpio_out(ipi, i, cpu->env.irq[6]);
> +            sysbus_mmio_map(SYS_BUS_DEVICE(ipi), i + 2, base);
> +        }
> +
> +        if (ase_lcsr_available(&MIPS_CPU(cpu)->env)) {
> +            MemoryRegion *core_iocsr = g_new(MemoryRegion, 1);
> +            g_autofree char *name = g_strdup_printf("core%d_iocsr", i);
> +            memory_region_init_alias(core_iocsr, OBJECT(cpu), name,
> +                                     iocsr, 0, UINT32_MAX);
> +            memory_region_add_subregion(&MIPS_CPU(cpu)->env.iocsr.mr,
> +                                        0, core_iocsr);
> +        }
> +
> +        if (node > 0) {
>               continue; /* Only node-0 can be connected to LIOINTC */
>           }
>   
>           for (ip = 0; ip < 4 ; ip++) {
> -            int pin = i * 4 + ip;
> +            int pin = core * LOONGSON3_CORE_PER_NODE + ip;
>               sysbus_connect_irq(SYS_BUS_DEVICE(liointc),
>                                  pin, cpu->env.irq[ip + 2]);
>           }