Re: [Qemu-devel] [RFC v3 08/15] hw/arm/boot: introduce fdt_add_memory_node helper

[Igor Mammedov <imammedo@redhat.com>]

On Tue,  3 Jul 2018 09:19:51 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> 
> We introduce an helper to create a memory node.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> 
> ---
> 
> v1 -> v2:
> - nop of existing /memory nodes was already handled
> ---
>  hw/arm/boot.c | 54 ++++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 34 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index e09201c..5243a25 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -413,6 +413,36 @@ static void set_kernel_args_old(const struct arm_boot_info *info,
>      }
>  }
>  
> +static int fdt_add_memory_node(void *fdt, uint32_t acells, hwaddr mem_base,
> +                               uint32_t scells, hwaddr mem_len,
> +                               int numa_node_id)
> +{
> +    char *nodename = NULL;
> +    int ret;
> +
> +    nodename = g_strdup_printf("/memory@%" PRIx64, mem_base);
> +    qemu_fdt_add_subnode(fdt, nodename);
> +    qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
> +    ret = qemu_fdt_setprop_sized_cells(fdt, nodename, "reg", acells, mem_base,
> +                                       scells, mem_len);
> +    if (ret < 0) {
> +        fprintf(stderr, "couldn't set %s/reg\n", nodename);
> +        goto out;
> +    }
> +    if (numa_node_id < 0) {
> +        goto out;
> +    }
> +
> +    ret = qemu_fdt_setprop_cell(fdt, nodename, "numa-node-id", numa_node_id);
> +    if (ret < 0) {
> +        fprintf(stderr, "couldn't set %s/numa-node-id\n", nodename);
> +    }
> +
> +out:
> +    g_free(nodename);
> +    return ret;
> +}
> +

not related question from hotplug POV,
is entry size fixed?
can we estimate exact size for #slots number of dimms and reserve it in advance
in FDT 'rom'?

>  static void fdt_add_psci_node(void *fdt)
>  {
>      uint32_t cpu_suspend_fn;
> @@ -492,7 +522,6 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
>      void *fdt = NULL;
>      int size, rc, n = 0;
>      uint32_t acells, scells;
> -    char *nodename;
>      unsigned int i;
>      hwaddr mem_base, mem_len;
>      char **node_path;
> @@ -566,35 +595,20 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
>          mem_base = binfo->loader_start;
>          for (i = 0; i < nb_numa_nodes; i++) {
>              mem_len = numa_info[i].node_mem;
> -            nodename = g_strdup_printf("/memory@%" PRIx64, mem_base);
> -            qemu_fdt_add_subnode(fdt, nodename);
> -            qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
> -            rc = qemu_fdt_setprop_sized_cells(fdt, nodename, "reg",
> -                                              acells, mem_base,
> -                                              scells, mem_len);
> +            rc = fdt_add_memory_node(fdt, acells, mem_base,
> +                                     scells, mem_len, i);
>              if (rc < 0) {
> -                fprintf(stderr, "couldn't set %s/reg for node %d\n", nodename,
> -                        i);
>                  goto fail;
>              }
>  
> -            qemu_fdt_setprop_cell(fdt, nodename, "numa-node-id", i);
>              mem_base += mem_len;
> -            g_free(nodename);
>          }
>      } else {
> -        nodename = g_strdup_printf("/memory@%" PRIx64, binfo->loader_start);
> -        qemu_fdt_add_subnode(fdt, nodename);
> -        qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
> -
> -        rc = qemu_fdt_setprop_sized_cells(fdt, nodename, "reg",
> -                                          acells, binfo->loader_start,
> -                                          scells, binfo->ram_size);
> +        rc = fdt_add_memory_node(fdt, acells, binfo->loader_start,
> +                                 scells, binfo->ram_size, -1);
>          if (rc < 0) {
> -            fprintf(stderr, "couldn't set %s reg\n", nodename);
>              goto fail;
>          }
> -        g_free(nodename);
>      }
>  
>      rc = fdt_path_offset(fdt, "/chosen");
nice cleanup, but I won't stop here just yet if hotplug to be considered.

I see arm_load_dtb() as a hack called from every board
where we dump everything that might be related to DTB regardless
if it's generic for every board or only a board specific stuff.

Could we split it in several logical parts that do a single thing
and preferably user only when they are actually need?
Something along following lines:
(cleanups/refactoring should be a separate from pcdimm series as it's self sufficient
and it would be easier to review/merge and could simplify following up pcdimm series):

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index e09201c..9c41efd 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@ -486,9 +486,6 @@ static void fdt_add_psci_node(void *fdt)
     qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
 }
 
-int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
-                 hwaddr addr_limit, AddressSpace *as)
-{
...

@@ -1158,9 +1158,14 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
     }
 
     if (!info->skip_dtb_autoload && have_dtb(info)) {
-        if (arm_load_dtb(info->dtb_start, info, info->dtb_limit, as) < 0) {
-            exit(1);
-        }
+        load_dtb_from_file() /* reuse generic machine_get_dtb() ??? */
+        create_dtb_memory_nodes() /* non numa variant */
+        /* move out mac-virt specific binfo->get_dtb into the board */
+        /* move out modify_dtb() which vexpress hack into vexpress */
+        /* move out fdt_add_psci_node() into mac-ivrt */
+        create_dtb_initrd_kernel_nodes()
+        dump_fdt()
+        rom_add_blob_fixed_as()
     }
 }
 
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 281ddcd..7686abf 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1285,9 +1285,12 @@ void virt_machine_done(Notifier *notifier, void *data)
                                        vms->memmap[VIRT_PLATFORM_BUS].size,
                                        vms->irqmap[VIRT_PLATFORM_BUS]);
     }
-    if (arm_load_dtb(info->dtb_start, info, info->dtb_limit, as) < 0) {
-        exit(1);
-    }
+    load_dtb_from_file()/get_dtb() stuff
+    virt_create_dtb_memory_nodes() /* incl. numa variant nad later pcdimm nodes */                         
+    fdt_add_psci_node()                         
+    create_dtb_initrd_kernel_nodes()                                         
+    dump_fdt()                                                               
+    rom_add_blob_fixed_as()
 
     virt_acpi_setup(vms);
     virt_build_smbios(vms);