Re: [PATCH qemu v6 5/6] spapr: Allow changing offset for -kernel image

[Fabiano Rosas <farosas@linux.ibm.com>]

Alexey Kardashevskiy <aik@ozlabs.ru> writes:

> This allows moving the kernel in the guest memory. The option is useful
> for step debugging (as Linux is linked at 0x0); it also allows loading
> grub which is normally linked to run at 0x20000.
>

+1, as this fixes half of the '-S' debugging issue.

> This uses the existing kernel address by default.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>

> ---
>  include/hw/ppc/spapr.h |  1 +
>  hw/ppc/spapr.c         | 38 +++++++++++++++++++++++++++++++-------
>  2 files changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 3b50f36c338a..32e831a395ae 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -164,6 +164,7 @@ struct SpaprMachineState {
>      void *fdt_blob;
>      long kernel_size;
>      bool kernel_le;
> +    uint64_t kernel_addr;
>      uint32_t initrd_base;
>      long initrd_size;
>      uint64_t rtc_offset; /* Now used only during incoming migration */
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 60153bf0b771..b59e9dc360fe 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1054,7 +1054,7 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, void *fdt)
>      }
>  
>      if (spapr->kernel_size) {
> -        uint64_t kprop[2] = { cpu_to_be64(KERNEL_LOAD_ADDR),
> +        uint64_t kprop[2] = { cpu_to_be64(spapr->kernel_addr),
>                                cpu_to_be64(spapr->kernel_size) };
>  
>          _FDT(fdt_setprop(fdt, chosen, "qemu,boot-kernel",
> @@ -1242,7 +1242,8 @@ void *spapr_build_fdt(SpaprMachineState *spapr, bool reset, size_t space)
>      /* Build memory reserve map */
>      if (reset) {
>          if (spapr->kernel_size) {
> -            _FDT((fdt_add_mem_rsv(fdt, KERNEL_LOAD_ADDR, spapr->kernel_size)));
> +            _FDT((fdt_add_mem_rsv(fdt, spapr->kernel_addr,
> +                                  spapr->kernel_size)));
>          }
>          if (spapr->initrd_size) {
>              _FDT((fdt_add_mem_rsv(fdt, spapr->initrd_base,
> @@ -1270,7 +1271,9 @@ void *spapr_build_fdt(SpaprMachineState *spapr, bool reset, size_t space)
>  
>  static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
>  {
> -    return (addr & 0x0fffffff) + KERNEL_LOAD_ADDR;
> +    SpaprMachineState *spapr = opaque;
> +
> +    return (addr & 0x0fffffff) + spapr->kernel_addr;
>  }
>  
>  static void emulate_spapr_hypercall(PPCVirtualHypervisor *vhyp,
> @@ -2947,14 +2950,15 @@ static void spapr_machine_init(MachineState *machine)
>          uint64_t lowaddr = 0;
>  
>          spapr->kernel_size = load_elf(kernel_filename, NULL,
> -                                      translate_kernel_address, NULL,
> +                                      translate_kernel_address, spapr,
>                                        NULL, &lowaddr, NULL, NULL, 1,
>                                        PPC_ELF_MACHINE, 0, 0);
>          if (spapr->kernel_size == ELF_LOAD_WRONG_ENDIAN) {
>              spapr->kernel_size = load_elf(kernel_filename, NULL,
> -                                          translate_kernel_address, NULL, NULL,
> +                                          translate_kernel_address, spapr, NULL,
>                                            &lowaddr, NULL, NULL, 0,
> -                                          PPC_ELF_MACHINE, 0, 0);
> +                                          PPC_ELF_MACHINE,
> +                                          0, 0);
>              spapr->kernel_le = spapr->kernel_size > 0;
>          }
>          if (spapr->kernel_size < 0) {
> @@ -2968,7 +2972,7 @@ static void spapr_machine_init(MachineState *machine)
>              /* Try to locate the initrd in the gap between the kernel
>               * and the firmware. Add a bit of space just in case
>               */
> -            spapr->initrd_base = (KERNEL_LOAD_ADDR + spapr->kernel_size
> +            spapr->initrd_base = (spapr->kernel_addr + spapr->kernel_size
>                                    + 0x1ffff) & ~0xffff;
>              spapr->initrd_size = load_image_targphys(initrd_filename,
>                                                       spapr->initrd_base,
> @@ -3214,6 +3218,18 @@ static void spapr_set_vsmt(Object *obj, Visitor *v, const char *name,
>      visit_type_uint32(v, name, (uint32_t *)opaque, errp);
>  }
>  
> +static void spapr_get_kernel_addr(Object *obj, Visitor *v, const char *name,
> +                                  void *opaque, Error **errp)
> +{
> +    visit_type_uint64(v, name, (uint64_t *)opaque, errp);
> +}
> +
> +static void spapr_set_kernel_addr(Object *obj, Visitor *v, const char *name,
> +                                  void *opaque, Error **errp)
> +{
> +    visit_type_uint64(v, name, (uint64_t *)opaque, errp);
> +}
> +
>  static char *spapr_get_ic_mode(Object *obj, Error **errp)
>  {
>      SpaprMachineState *spapr = SPAPR_MACHINE(obj);
> @@ -3319,6 +3335,14 @@ static void spapr_instance_init(Object *obj)
>      object_property_add_bool(obj, "vfio-no-msix-emulation",
>                               spapr_get_msix_emulation, NULL, NULL);
>  
> +    object_property_add(obj, "kernel-addr", "uint64", spapr_get_kernel_addr,
> +                        spapr_set_kernel_addr, NULL, &spapr->kernel_addr,
> +                        &error_abort);
> +    object_property_set_description(obj, "kernel-addr",
> +                                    stringify(KERNEL_LOAD_ADDR)
> +                                    " for -kernel is the default",
> +                                    NULL);
> +    spapr->kernel_addr = KERNEL_LOAD_ADDR;
>      /* The machine class defines the default interrupt controller mode */
>      spapr->irq = smc->irq;
>      object_property_add_str(obj, "ic-mode", spapr_get_ic_mode,