Re: [Qemu-devel] [PATCH v6 12/18] hw/arm/boot: Expose the PC-DIMM nodes in the DT

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 20 Feb 2019 16:30:13 +0100
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Igor,
> 
> On 2/18/19 9:58 AM, Igor Mammedov wrote:
> > On Tue,  5 Feb 2019 18:33:00 +0100
> > Eric Auger <eric.auger@redhat.com> wrote:
> >   
> >> From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> >>
> >> This patch add memory nodes corresponding to PC-DIMM regions.  
> > s/add/adds/ or s/This patch add/Add/
> >   
> >>
> >> NV_DIMM and ACPI_NVDIMM configs are not yet set for ARM so we
> >> don't need to care about NV-DIMM at this stage.
> >>
> >> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> >> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> >>
> >> ---
> >> v3 -> v4:
> >> - git rid of @base and @len in fdt_add_hotpluggable_memory_nodes
> >>
> >> v1 -> v2:
> >> - added qapi_free_MemoryDeviceInfoList and simplify the loop
> >> ---
> >>  hw/arm/boot.c | 35 +++++++++++++++++++++++++++++++++++
> >>  1 file changed, 35 insertions(+)
> >>
> >> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> >> index 2ef367e15b..2a70e8aa82 100644
> >> --- a/hw/arm/boot.c
> >> +++ b/hw/arm/boot.c
> >> @@ -19,6 +19,7 @@
> >>  #include "sysemu/numa.h"
> >>  #include "hw/boards.h"
> >>  #include "hw/loader.h"
> >> +#include "hw/mem/memory-device.h"
> >>  #include "elf.h"
> >>  #include "sysemu/device_tree.h"
> >>  #include "qemu/config-file.h"
> >> @@ -526,6 +527,34 @@ static void fdt_add_psci_node(void *fdt)
> >>      qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
> >>  }
> >>  
> >> +static int fdt_add_hotpluggable_memory_nodes(void *fdt,
> >> +                                             uint32_t acells, uint32_t scells) {
> >> +    MemoryDeviceInfoList *info, *info_list = qmp_memory_device_list();
> >> +    MemoryDeviceInfo *mi;
> >> +    PCDIMMDeviceInfo *di;
> >> +    bool is_nvdimm;
> >> +    int ret = 0;
> >> +
> >> +    for (info = info_list; info != NULL; info = info->next) {
> >> +        mi = info->value;
> >> +        is_nvdimm = (mi->type == MEMORY_DEVICE_INFO_KIND_NVDIMM);
> >> +        di = !is_nvdimm ? mi->u.dimm.data : mi->u.nvdimm.data;
> >> +
> >> +        if (is_nvdimm) {
> >> +            ret = -ENOENT; /* NV-DIMM not yet supported */
> >> +        } else {
> >> +            ret = fdt_add_memory_node(fdt, acells, di->addr,
> >> +                                      scells, di->size, di->node);
> >> +        }
> >> +        if (ret < 0) {
> >> +            goto out;
> >> +        }
> >> +    }
> >> +out:
> >> +    qapi_free_MemoryDeviceInfoList(info_list);
> >> +    return ret;
> >> +}
> >> +
> >>  int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
> >>                   hwaddr addr_limit, AddressSpace *as)
> >>  {
> >> @@ -621,6 +650,12 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
> >>          }
> >>      }
> >>  
> >> +    rc = fdt_add_hotpluggable_memory_nodes(fdt, acells, scells);
> >> +    if (rc < 0) {
> >> +            fprintf(stderr, "couldn't add hotpluggable memory nodes\n");  
> > error message is rather vague, user using nvdimms + pc-dimms on CLI won't have
> > a clue that the former is not supported.
> > Suggest pass in error_fatal as argument and report more specific error from
> > fdt_add_hotpluggable_memory_nodes()
> > 
> > does this run on reboot?  
> 
> Yes after a QMP system_reset I can see the DIMMS on guest in /proc/meminfo
it siims that dimms come from ACPI and not DTB.

My worry was that arm_load_dtb() always end up with exit(1) on failure but it seems
that it's not called on reboot so it should be fine.

> 
> Thanks
> 
> Eric
> >   
> >> +            goto fail;
> >> +    }
> >> +
> >>      rc = fdt_path_offset(fdt, "/chosen");
> >>      if (rc < 0) {
> >>          qemu_fdt_add_subnode(fdt, "/chosen");  
> >