Re: [Qemu-devel] [qemu PATCH 5/5] nvdimm: make persistence option symbolic

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 07, 2018 at 04:31:11PM -0600, Ross Zwisler wrote:
> Replace the "nvdimm-cap" option which took numeric arguments such as "2"
> with a more user friendly "nvdimm-persistence" option which takes symbolic
> arguments "cpu" or "mem-ctrl".
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  docs/nvdimm.txt          | 31 ++++++++++++-------------------
>  hw/acpi/nvdimm.c         |  4 ++--
>  hw/i386/pc.c             | 35 +++++++++++++++++------------------
>  include/hw/i386/pc.h     |  2 +-
>  include/hw/mem/nvdimm.h  |  3 ++-
>  tests/bios-tables-test.c |  2 +-
>  6 files changed, 35 insertions(+), 42 deletions(-)
> 
> diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt
> index 8b48fb4633..24b443b655 100644
> --- a/docs/nvdimm.txt
> +++ b/docs/nvdimm.txt
> @@ -154,29 +154,22 @@ guest software that this vNVDIMM device contains a region that cannot
>  accept persistent writes. In result, for example, the guest Linux
>  NVDIMM driver, marks such vNVDIMM device as read-only.
>  
> -Platform Capabilities
> ----------------------
> +NVDIMM Persistence
> +------------------
>  
>  ACPI 6.2 Errata A added support for a new Platform Capabilities Structure
>  which allows the platform to communicate what features it supports related to
> -NVDIMM data durability.  Users can provide a capabilities value to a guest via
> -the optional "nvdimm-cap" machine command line option:
> +NVDIMM data persistence.  Users can provide a persistence value to a guest via
> +the optional "nvdimm-persistence" machine command line option:
>  
> -    -machine pc,accel=kvm,nvdimm,nvdimm-cap=2
> +    -machine pc,accel=kvm,nvdimm,nvdimm-persistence=cpu
>  
> -This "nvdimm-cap" field is an integer, and is the combined value of the
> -various capability bits defined in table 5-137 of the ACPI 6.2 Errata A spec.
> +There are currently two valid values for this option:
>  
> -Here is a quick summary of the three bits that are defined as of that spec:
> +"mem-ctrl" - The platform supports flushing dirty data from the memory
> +             controller to the NVDIMMs in the event of power loss.
>  
> -Bit[0] - CPU Cache Flush to NVDIMM Durability on Power Loss Capable.
> -Bit[1] - Memory Controller Flush to NVDIMM Durability on Power Loss Capable.
> -         Note: If bit 0 is set to 1 then this bit shall be set to 1 as well.
> -Bit[2] - Byte Addressable Persistent Memory Hardware Mirroring Capable.
> -
> -So, a "nvdimm-cap" value of 2 would mean that the platform supports Memory
> -Controller Flush on Power Loss, a value of 3 would mean that the platform
> -supports CPU Cache Flush and Memory Controller Flush on Power Loss, etc.
> -
> -For a complete list of the flags available and for more detailed descriptions,
> -please consult the ACPI spec.
> +"cpu"      - The platform supports flushing dirty data from the CPU cache to
> +             the NVDIMMs in the event of power loss.  This implies that the
> +             platform also supports flushing dirty data through the memory
> +             controller on power loss.
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 87e4280c71..27eeb6609f 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -404,8 +404,8 @@ static GArray *nvdimm_build_device_structure(AcpiNVDIMMState *state)
>      }
>      g_slist_free(device_list);
>  
> -    if (state->capabilities) {
> -        nvdimm_build_structure_caps(structures, state->capabilities);
> +    if (state->persistence) {
> +        nvdimm_build_structure_caps(structures, state->persistence);
>      }
>  
>      return structures;
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index f3befe6721..5bba9dcf5a 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2181,31 +2181,30 @@ static void pc_machine_set_nvdimm(Object *obj, bool value, Error **errp)
>      pcms->acpi_nvdimm_state.is_enabled = value;
>  }
>  
> -static void pc_machine_get_nvdimm_capabilities(Object *obj, Visitor *v,
> -                                               const char *name, void *opaque,
> -                                               Error **errp)
> +static char *pc_machine_get_nvdimm_persistence(Object *obj, Error **errp)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> -    uint32_t value = pcms->acpi_nvdimm_state.capabilities;
>  
> -    visit_type_uint32(v, name, &value, errp);
> +    return g_strdup(pcms->acpi_nvdimm_state.persistence_string);
>  }
>  
> -static void pc_machine_set_nvdimm_capabilities(Object *obj, Visitor *v,
> -                                               const char *name, void *opaque,
> +static void pc_machine_set_nvdimm_persistence(Object *obj, const char *value,
>                                                 Error **errp)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> -    Error *error = NULL;
> -    uint32_t value;
> -
> -    visit_type_uint32(v, name, &value, &error);
> -    if (error) {
> -        error_propagate(errp, error);
> -        return;
> +    AcpiNVDIMMState *nvdimm_state = &pcms->acpi_nvdimm_state;
> +
> +    if (strcmp(value, "cpu") == 0)
> +        nvdimm_state->persistence = 3;
> +    else if (strcmp(value, "mem-ctrl") == 0)
> +        nvdimm_state->persistence = 2;
> +    else {
> +        error_report("-machine nvdimm-persistence=%s: unsupported option", value);
> +        exit(EXIT_FAILURE);
>      }
>  
> -    pcms->acpi_nvdimm_state.capabilities = value;
> +    g_free(nvdimm_state->persistence_string);
> +    nvdimm_state->persistence_string = g_strdup(value);
>  }
>  
>  static bool pc_machine_get_smbus(Object *obj, Error **errp)
> @@ -2421,9 +2420,9 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>      object_class_property_add_bool(oc, PC_MACHINE_NVDIMM,
>          pc_machine_get_nvdimm, pc_machine_set_nvdimm, &error_abort);
>  
> -    object_class_property_add(oc, PC_MACHINE_NVDIMM_CAP, "uint32",
> -        pc_machine_get_nvdimm_capabilities,
> -        pc_machine_set_nvdimm_capabilities, NULL, NULL, &error_abort);
> +    object_class_property_add_str(oc, PC_MACHINE_NVDIMM_PERSIST,
> +        pc_machine_get_nvdimm_persistence,
> +        pc_machine_set_nvdimm_persistence, &error_abort);
>  
>      object_class_property_add_bool(oc, PC_MACHINE_SMBUS,
>          pc_machine_get_smbus, pc_machine_set_smbus, &error_abort);
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 04d1f8c6c3..fc8dedca12 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -76,7 +76,7 @@ struct PCMachineState {
>  #define PC_MACHINE_VMPORT           "vmport"
>  #define PC_MACHINE_SMM              "smm"
>  #define PC_MACHINE_NVDIMM           "nvdimm"
> -#define PC_MACHINE_NVDIMM_CAP       "nvdimm-cap"
> +#define PC_MACHINE_NVDIMM_PERSIST   "nvdimm-persistence"
>  #define PC_MACHINE_SMBUS            "smbus"
>  #define PC_MACHINE_SATA             "sata"
>  #define PC_MACHINE_PIT              "pit"
> diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
> index 3c82751bab..9340631cfc 100644
> --- a/include/hw/mem/nvdimm.h
> +++ b/include/hw/mem/nvdimm.h
> @@ -138,7 +138,8 @@ struct AcpiNVDIMMState {
>      /*
>       * Platform capabilities, section 5.2.25.9 of ACPI 6.2 Errata A
>       */
> -    int32_t capabilities;
> +    int32_t persistence;
> +    char    *persistence_string;
>  };
>  typedef struct AcpiNVDIMMState AcpiNVDIMMState;
>  
> diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c
> index 9b5db1ee8f..b95d56aa4e 100644
> --- a/tests/bios-tables-test.c
> +++ b/tests/bios-tables-test.c
> @@ -831,7 +831,7 @@ static void test_acpi_tcg_dimm_pxm(const char *machine)
>      memset(&data, 0, sizeof(data));
>      data.machine = machine;
>      data.variant = ".dimmpxm";
> -    test_acpi_one(" -machine nvdimm=on,nvdimm-cap=3"
> +    test_acpi_one(" -machine nvdimm=on,nvdimm-persistence=cpu"
>                    " -smp 4,sockets=4"
>                    " -m 128M,slots=3,maxmem=1G"
>                    " -numa node,mem=32M,nodeid=0"
> -- 
> 2.14.4