Re: [Qemu-devel] [PATCH v3 2/5] pc, pc-dimm: Factor out reusable parts in pc_dimm_plug to a separate routine

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 26 Jun 2015 09:36:01 +0530
Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:

> pc_dimm_plug() has code that will be needed for memory plug handlers
> in other archs too. Extract code from pc_dimm_plug() into a generic
> routine pc_dimm_memory_plug() that resides in pc-dimm.c. Also
> correspondingly refactor re-usable unplug code into pc_dimm_memory_unplug().
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
thanks for splitting, much easier to review.


> ---
>  hw/i386/pc.c             | 66 ++++-----------------------------------
>  hw/mem/pc-dimm.c         | 80 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/mem/pc-dimm.h |  4 +++
>  3 files changed, 90 insertions(+), 60 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index e51c3be..cb57612 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -64,7 +64,6 @@
>  #include "hw/pci/pci_host.h"
>  #include "acpi-build.h"
>  #include "hw/mem/pc-dimm.h"
> -#include "trace.h"
>  #include "qapi/visitor.h"
>  #include "qapi-visit.h"
>  
> @@ -1554,88 +1553,35 @@ void ioapic_init_gsi(GSIState *gsi_state, const char *parent_name)
>  static void pc_dimm_plug(HotplugHandler *hotplug_dev,
>                           DeviceState *dev, Error **errp)
>  {
> -    int slot;
>      HotplugHandlerClass *hhc;
>      Error *local_err = NULL;
>      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> -    MachineState *machine = MACHINE(hotplug_dev);
>      PCDIMMDevice *dimm = PC_DIMM(dev);
>      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
>      MemoryRegion *mr = ddc->get_memory_region(dimm);
> -    uint64_t existing_dimms_capacity = 0;
>      uint64_t align = TARGET_PAGE_SIZE;
> -    uint64_t addr;
> -
> -    addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
>  
>      if (memory_region_get_alignment(mr) && pcms->enforce_aligned_dimm) {
>          align = memory_region_get_alignment(mr);
>      }
>  
> -    addr = pc_dimm_get_free_addr(pcms->hotplug_memory.base,
> -                                 memory_region_size(&pcms->hotplug_memory.mr),
> -                                 !addr ? NULL : &addr, align,
> -                                 memory_region_size(mr), &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
> -    existing_dimms_capacity = pc_existing_dimms_capacity(&local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
> -    if (existing_dimms_capacity + memory_region_size(mr) >
> -        machine->maxram_size - machine->ram_size) {
> -        error_setg(&local_err, "not enough space, currently 0x%" PRIx64
> -                   " in use of total hot pluggable 0x" RAM_ADDR_FMT,
> -                   existing_dimms_capacity,
> -                   machine->maxram_size - machine->ram_size);
> -        goto out;
> -    }
> -
> -    object_property_set_int(OBJECT(dev), addr, PC_DIMM_ADDR_PROP, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -    trace_mhp_pc_dimm_assigned_address(addr);
> -
> -    slot = object_property_get_int(OBJECT(dev), PC_DIMM_SLOT_PROP, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
> -    slot = pc_dimm_get_free_slot(slot == PC_DIMM_UNASSIGNED_SLOT ? NULL : &slot,
> -                                 machine->ram_slots, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -    object_property_set_int(OBJECT(dev), slot, PC_DIMM_SLOT_PROP, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -    trace_mhp_pc_dimm_assigned_slot(slot);
> -
>      if (!pcms->acpi_dev) {
>          error_setg(&local_err,
>                     "memory hotplug is not enabled: missing acpi device");
>          goto out;
>      }
>  
> -    if (kvm_enabled() && !kvm_has_free_slot(machine)) {
> -        error_setg(&local_err, "hypervisor has no free memory slots left");
> +    pc_dimm_memory_plug(dev, &pcms->hotplug_memory, mr, align, &local_err);
> +    if (local_err) {
>          goto out;
>      }
>  
> -    memory_region_add_subregion(&pcms->hotplug_memory.mr,
> -                                addr - pcms->hotplug_memory.base, mr);
> -    vmstate_register_ram(mr, dev);
> -
>      hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
>      hhc->plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);
> +    if (local_err) {
> +        pc_dimm_memory_unplug(dev, &pcms->hotplug_memory, mr);
> +    }
You are adding something new while patch claims to be just moving code.
I'm not sure it's save to call unplug here if hhc->plug() failed
since it might have triggered guest visible side effects.

I'd just drop this hunk and leave original code,
on top of that extra patch for hhc->plug(s/local_err/error_abort/)
might make a sense since hhc->plug() should never fail and if it's
then we should fix error in code instead of trying to recover.

>  out:
>      error_propagate(errp, local_err);
>  }
> diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> index e70633d..98971b7 100644
> --- a/hw/mem/pc-dimm.c
> +++ b/hw/mem/pc-dimm.c
> @@ -23,12 +23,92 @@
>  #include "qapi/visitor.h"
>  #include "qemu/range.h"
>  #include "sysemu/numa.h"
> +#include "sysemu/kvm.h"
> +#include "trace.h"
>  
>  typedef struct pc_dimms_capacity {
>       uint64_t size;
>       Error    **errp;
>  } pc_dimms_capacity;
>  
> +void pc_dimm_memory_plug(DeviceState *dev, MemoryHotplugState *hpms,
> +                         MemoryRegion *mr, uint64_t align, Error **errp)
> +{
> +    int slot;
> +    MachineState *machine = MACHINE(qdev_get_machine());
> +    PCDIMMDevice *dimm = PC_DIMM(dev);
> +    Error *local_err = NULL;
> +    uint64_t existing_dimms_capacity = 0;
> +    uint64_t addr;
> +
> +    addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP, &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
> +    addr = pc_dimm_get_free_addr(hpms->base,
> +                                 memory_region_size(&hpms->mr),
> +                                 !addr ? NULL : &addr, align,
> +                                 memory_region_size(mr), &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
> +    existing_dimms_capacity = pc_existing_dimms_capacity(&local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
> +    if (existing_dimms_capacity + memory_region_size(mr) >
> +        machine->maxram_size - machine->ram_size) {
> +        error_setg(&local_err, "not enough space, currently 0x%" PRIx64
> +                   " in use of total hot pluggable 0x" RAM_ADDR_FMT,
> +                   existing_dimms_capacity,
> +                   machine->maxram_size - machine->ram_size);
> +        goto out;
> +    }
> +
> +    object_property_set_int(OBJECT(dev), addr, PC_DIMM_ADDR_PROP, &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +    trace_mhp_pc_dimm_assigned_address(addr);
> +
> +    slot = object_property_get_int(OBJECT(dev), PC_DIMM_SLOT_PROP, &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
> +    slot = pc_dimm_get_free_slot(slot == PC_DIMM_UNASSIGNED_SLOT ? NULL : &slot,
> +                                 machine->ram_slots, &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +    object_property_set_int(OBJECT(dev), slot, PC_DIMM_SLOT_PROP, &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +    trace_mhp_pc_dimm_assigned_slot(slot);
> +
> +    if (kvm_enabled() && !kvm_has_free_slot(machine)) {
> +        error_setg(&local_err, "hypervisor has no free memory slots left");
> +        goto out;
> +    }
> +
> +    memory_region_add_subregion(&hpms->mr, addr - hpms->base, mr);
> +    vmstate_register_ram(mr, dev);
> +
> +out:
> +    error_propagate(errp, local_err);
> +}
> +
> +void pc_dimm_memory_unplug(DeviceState *dev, MemoryHotplugState *hpms,
> +                           MemoryRegion *mr)
> +{
> +    memory_region_del_subregion(&hpms->mr, mr);
> +    vmstate_unregister_ram(mr, dev);
> +}
if you adding this here then you probably should be removing/replacing
related hunks from pc.c, I don't see it in this patch.

> +
>  static int pc_existing_dimms_capacity_internal(Object *obj, void *opaque)
>  {
>      pc_dimms_capacity *cap = opaque;
> diff --git a/include/hw/mem/pc-dimm.h b/include/hw/mem/pc-dimm.h
> index d528a3f..3eabef4 100644
> --- a/include/hw/mem/pc-dimm.h
> +++ b/include/hw/mem/pc-dimm.h
> @@ -90,4 +90,8 @@ int pc_dimm_get_free_slot(const int *hint, int max_slots, Error **errp);
>  
>  int qmp_pc_dimm_device_list(Object *obj, void *opaque);
>  uint64_t pc_existing_dimms_capacity(Error **errp);
> +void pc_dimm_memory_plug(DeviceState *dev, MemoryHotplugState *hpms,
> +                         MemoryRegion *mr, uint64_t align, Error **errp);
> +void pc_dimm_memory_unplug(DeviceState *dev, MemoryHotplugState *hpms,
> +                           MemoryRegion *mr);
>  #endif