Re: [Qemu-devel] [qemu PATCH v4 3/4] nvdimm, acpi: support NFIT platform capabilities

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

On Mon, May 21, 2018 at 10:32:02AM -0600, Ross Zwisler wrote:
> Add a machine command line option to allow the user to control the Platform
> Capabilities Structure in the virtualized NFIT.  This Platform Capabilities
> Structure was added in ACPI 6.2 Errata A.
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

I tried playing with it and encoding the capabilities is
quite awkward.

Can we add bits for specific capabilities instead of nvdimm-cap?

How about:

"cpu-flush-on-power-loss-cap"
"memory-flush-on-power-loss-cap"
"byte-addressable-mirroring-cap"

?



> ---
>  docs/nvdimm.txt         | 27 +++++++++++++++++++++++++++
>  hw/acpi/nvdimm.c        | 45 +++++++++++++++++++++++++++++++++++++++++----
>  hw/i386/pc.c            | 31 +++++++++++++++++++++++++++++++
>  include/hw/i386/pc.h    |  1 +
>  include/hw/mem/nvdimm.h |  5 +++++
>  5 files changed, 105 insertions(+), 4 deletions(-)
> 
> diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt
> index e903d8bb09..8b48fb4633 100644
> --- a/docs/nvdimm.txt
> +++ b/docs/nvdimm.txt
> @@ -153,3 +153,30 @@ guest NVDIMM region mapping structure.  This unarmed flag indicates
>  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
> +---------------------
> +
> +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:
> +
> +    -machine pc,accel=kvm,nvdimm,nvdimm-cap=2
> +
> +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.
> +
> +Here is a quick summary of the three bits that are defined as of that spec:
> +
> +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.
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 59d6e4254c..87e4280c71 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -169,6 +169,21 @@ struct NvdimmNfitControlRegion {
>  } QEMU_PACKED;
>  typedef struct NvdimmNfitControlRegion NvdimmNfitControlRegion;
>  
> +/*
> + * NVDIMM Platform Capabilities Structure
> + *
> + * Defined in section 5.2.25.9 of ACPI 6.2 Errata A, September 2017
> + */
> +struct NvdimmNfitPlatformCaps {
> +    uint16_t type;
> +    uint16_t length;
> +    uint8_t highest_cap;
> +    uint8_t reserved[3];
> +    uint32_t capabilities;
> +    uint8_t reserved2[4];
> +} QEMU_PACKED;
> +typedef struct NvdimmNfitPlatformCaps NvdimmNfitPlatformCaps;
> +
>  /*
>   * Module serial number is a unique number for each device. We use the
>   * slot id of NVDIMM device to generate this number so that each device
> @@ -351,7 +366,23 @@ static void nvdimm_build_structure_dcr(GArray *structures, DeviceState *dev)
>                                           JEDEC Annex L Release 3. */);
>  }
>  
> -static GArray *nvdimm_build_device_structure(void)
> +/*
> + * ACPI 6.2 Errata A: 5.2.25.9 NVDIMM Platform Capabilities Structure
> + */
> +static void
> +nvdimm_build_structure_caps(GArray *structures, uint32_t capabilities)
> +{
> +    NvdimmNfitPlatformCaps *nfit_caps;
> +
> +    nfit_caps = acpi_data_push(structures, sizeof(*nfit_caps));
> +
> +    nfit_caps->type = cpu_to_le16(7 /* NVDIMM Platform Capabilities */);
> +    nfit_caps->length = cpu_to_le16(sizeof(*nfit_caps));
> +    nfit_caps->highest_cap = 31 - clz32(capabilities);
> +    nfit_caps->capabilities = cpu_to_le32(capabilities);
> +}
> +
> +static GArray *nvdimm_build_device_structure(AcpiNVDIMMState *state)
>  {
>      GSList *device_list = nvdimm_get_device_list();
>      GArray *structures = g_array_new(false, true /* clear */, 1);
> @@ -373,6 +404,10 @@ static GArray *nvdimm_build_device_structure(void)
>      }
>      g_slist_free(device_list);
>  
> +    if (state->capabilities) {
> +        nvdimm_build_structure_caps(structures, state->capabilities);
> +    }
> +
>      return structures;
>  }
>  
> @@ -381,16 +416,18 @@ static void nvdimm_init_fit_buffer(NvdimmFitBuffer *fit_buf)
>      fit_buf->fit = g_array_new(false, true /* clear */, 1);
>  }
>  
> -static void nvdimm_build_fit_buffer(NvdimmFitBuffer *fit_buf)
> +static void nvdimm_build_fit_buffer(AcpiNVDIMMState *state)
>  {
> +    NvdimmFitBuffer *fit_buf = &state->fit_buf;
> +
>      g_array_free(fit_buf->fit, true);
> -    fit_buf->fit = nvdimm_build_device_structure();
> +    fit_buf->fit = nvdimm_build_device_structure(state);
>      fit_buf->dirty = true;
>  }
>  
>  void nvdimm_plug(AcpiNVDIMMState *state)
>  {
> -    nvdimm_build_fit_buffer(&state->fit_buf);
> +    nvdimm_build_fit_buffer(state);
>  }
>  
>  static void nvdimm_build_nfit(AcpiNVDIMMState *state, GArray *table_offsets,
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d768930d02..1b2684c549 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2182,6 +2182,33 @@ 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)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +    uint32_t value = pcms->acpi_nvdimm_state.capabilities;
> +
> +    visit_type_uint32(v, name, &value, errp);
> +}
> +
> +static void pc_machine_set_nvdimm_capabilities(Object *obj, Visitor *v,
> +                                               const char *name, void *opaque,
> +                                               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;
> +    }
> +
> +    pcms->acpi_nvdimm_state.capabilities = value;
> +}
> +
>  static bool pc_machine_get_smbus(Object *obj, Error **errp)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> @@ -2395,6 +2422,10 @@ 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_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 2a98e3ad68..e9b22f929c 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -76,6 +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_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 74c60332e1..3c82751bab 100644
> --- a/include/hw/mem/nvdimm.h
> +++ b/include/hw/mem/nvdimm.h
> @@ -134,6 +134,11 @@ struct AcpiNVDIMMState {
>  
>      /* the IO region used by OSPM to transfer control to QEMU. */
>      MemoryRegion io_mr;
> +
> +    /*
> +     * Platform capabilities, section 5.2.25.9 of ACPI 6.2 Errata A
> +     */
> +    int32_t capabilities;
>  };
>  typedef struct AcpiNVDIMMState AcpiNVDIMMState;
>  
> -- 
> 2.14.3