Re: [Qemu-devel] [PATCH 08/11] pc: align DIMM's address/size by backend's alignment value

[Andrey Korolyov]

On Fri, Oct 31, 2014 at 7:38 PM, Igor Mammedov <address@hidden> wrote:
> Performance wise it's better to align GVA by the backend's
> page size.
>
> Also do not allow to create DIMM device with suboptimal
> size (i.e. not aligned to backends page size) to aviod
> memory loss.
>
> Do above only for 2.2 and newer machine types to avoid
> breaking working configs with 2.1 machine type.
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/i386/pc.c         | 15 +++++++++++++++
>  hw/i386/pc_piix.c    |  3 +++
>  hw/i386/pc_q35.c     |  3 +++
>  include/hw/i386/pc.h |  4 ++++
>  4 files changed, 25 insertions(+)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 1460074..ed50344 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1605,6 +1605,10 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
>          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),
>                                   !addr ? NULL : &addr, align,
> @@ -1727,6 +1731,13 @@ static void pc_machine_set_max_ram_below_4g(Object 
> *obj, Visitor *v,
>      pcms->max_ram_below_4g = value;
>  }
>
> +static bool pc_machine_get_aligned_dimm(Object *obj, Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +
> +    return pcms->enforce_aligned_dimm;
> +}
> +
>  static void pc_machine_initfn(Object *obj)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> @@ -1739,6 +1750,10 @@ static void pc_machine_initfn(Object *obj)
>                          pc_machine_get_max_ram_below_4g,
>                          pc_machine_set_max_ram_below_4g,
>                          NULL, NULL, NULL);
> +    pcms->enforce_aligned_dimm = true;
> +    object_property_add_bool(obj, PC_MACHINE_ENFORCE_ALINED_DIMM,
> +                             pc_machine_get_aligned_dimm,
> +                             NULL, NULL);
>  }
>
>  static void pc_machine_class_init(ObjectClass *oc, void *data)
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 162b77e..4adcd9b 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -304,6 +304,9 @@ static void pc_init_pci(MachineState *machine)
>
>  static void pc_compat_2_1(MachineState *machine)
>  {
> +    PCMachineState *pcms = PC_MACHINE(machine);
> +
> +    pcms->enforce_aligned_dimm = false;
>  }
>
>  static void pc_compat_2_0(MachineState *machine)
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 0490980..cf4953e 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -282,6 +282,9 @@ static void pc_q35_init(MachineState *machine)
>
>  static void pc_compat_2_1(MachineState *machine)
>  {
> +    PCMachineState *pcms = PC_MACHINE(machine);
> +
> +    pcms->enforce_aligned_dimm = false;
>  }
>
>  static void pc_compat_2_0(MachineState *machine)
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index c4ee520..a4e2a39 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -23,6 +23,8 @@
>   * address space begins.
>   * @hotplug_memory: hotplug memory addess space container
>   * @acpi_dev: link to ACPI PM device that performs ACPI hotplug handling
> + * @enforce_aligned_dimm: check that DIMM's address/size is aligned by
> + *                        backend's alignment value if provided
>   */
>  struct PCMachineState {
>      /*< private >*/
> @@ -35,11 +37,13 @@ struct PCMachineState {
>      HotplugHandler *acpi_dev;
>
>      uint64_t max_ram_below_4g;
> +    bool enforce_aligned_dimm;
>  };
>
>  #define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
>  #define PC_MACHINE_MEMHP_REGION_SIZE "hotplug-memory-region-size"
>  #define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
> +#define PC_MACHINE_ENFORCE_ALINED_DIMM "enforce-aligned-dimm"
>
>  /**
>   * PCMachineClass:
> --
> 1.8.3.1
>
>


Spell: ALINED.