Re: [PATCH v4 28/33] nvdimm acpi: support DSM_FUN_IMPLEMENTED function

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: pbonzini@redhat.com, imammedo@redhat.com, gleb@kernel.org,
	mtosatti@redhat.com, stefanha@redhat.com, rth@twiddle.net,
	ehabkost@redhat.com, dan.j.williams@intel.com,
	kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [PATCH v4 28/33] nvdimm acpi: support DSM_FUN_IMPLEMENTED function
Date: Sun, 18 Oct 2015 21:05:24 +0300	[thread overview]
Message-ID: <20151018205030-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <1445216059-88521-29-git-send-email-guangrong.xiao@linux.intel.com>

On Mon, Oct 19, 2015 at 08:54:14AM +0800, Xiao Guangrong wrote:
> __DSM is defined in ACPI 6.0: 9.14.1 _DSM (Device Specific Method)
> 
> Function 0 is a query function. We do not support any function on root
> device and only 3 functions are support for NVDIMM device,
> DSM_DEV_FUN_NAMESPACE_LABEL_SIZE, DSM_DEV_FUN_GET_NAMESPACE_LABEL_DATA and
> DSM_DEV_FUN_SET_NAMESPACE_LABEL_DATA, that means we currently only allow to
> access device's Label Namespace
> 
> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> ---
>  hw/acpi/nvdimm.c | 184 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 182 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index b211b8b..37fea1c 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -260,6 +260,22 @@ static uint32_t nvdimm_slot_to_dcr_index(int slot)
>      return nvdimm_slot_to_spa_index(slot) + 1;
>  }
>  
> +static NVDIMMDevice
> +*nvdimm_get_device_by_handle(GSList *list, uint32_t handle)
> +{
> +    for (; list; list = list->next) {
> +        NVDIMMDevice *nvdimm = list->data;
> +        int slot = object_property_get_int(OBJECT(nvdimm), DIMM_SLOT_PROP,
> +                                           NULL);
> +
> +        if (nvdimm_slot_to_handle(slot) == handle) {
> +            return nvdimm;
> +        }
> +    }
> +
> +    return NULL;
> +}
> +
>  /*
>   * Please refer to ACPI 6.0: 5.2.25.1 System Physical Address Range
>   * Structure
> @@ -411,6 +427,60 @@ static void nvdimm_build_nfit(GArray *structures, GArray *table_offsets,
>  /* detailed _DSM design please refer to docs/specs/acpi_nvdimm.txt */
>  #define NOTIFY_VALUE      0x99

Again, please prefix everything consistently.

>  
> +enum {
> +    DSM_FUN_IMPLEMENTED = 0,
> +
> +    /* NVDIMM Root Device Functions */
> +    DSM_ROOT_DEV_FUN_ARS_CAP = 1,
> +    DSM_ROOT_DEV_FUN_ARS_START = 2,
> +    DSM_ROOT_DEV_FUN_ARS_QUERY = 3,
> +
> +    /* NVDIMM Device (non-root) Functions */
> +    DSM_DEV_FUN_SMART = 1,
> +    DSM_DEV_FUN_SMART_THRESHOLD = 2,
> +    DSM_DEV_FUN_BLOCK_NVDIMM_FLAGS = 3,
> +    DSM_DEV_FUN_NAMESPACE_LABEL_SIZE = 4,
> +    DSM_DEV_FUN_GET_NAMESPACE_LABEL_DATA = 5,
> +    DSM_DEV_FUN_SET_NAMESPACE_LABEL_DATA = 6,
> +    DSM_DEV_FUN_VENDOR_EFFECT_LOG_SIZE = 7,
> +    DSM_DEV_FUN_GET_VENDOR_EFFECT_LOG = 8,
> +    DSM_DEV_FUN_VENDOR_SPECIFIC = 9,
> +};

Does FUN stand for "function"? FUNC or FN is probably better.

Please list exact names as they appear in spec so
they can be searched for.

> +
> +enum {
> +    /* Common return status codes. */
> +    DSM_STATUS_SUCCESS = 0,                   /* Success */
> +    DSM_STATUS_NOT_SUPPORTED = 1,             /* Not Supported */
> +
> +    /* NVDIMM Root Device _DSM function return status codes*/
> +    DSM_ROOT_DEV_STATUS_INVALID_PARAS = 2,    /* Invalid Input Parameters */
> +    DSM_ROOT_DEV_STATUS_FUNCTION_SPECIFIC_ERROR = 3, /* Function-Specific
> +                                                        Error */
> +
> +    /* NVDIMM Device (non-root) _DSM function return status codes*/
> +    DSM_DEV_STATUS_NON_EXISTING_MEM_DEV = 2,  /* Non-Existing Memory Device */
> +    DSM_DEV_STATUS_INVALID_PARAS = 3,         /* Invalid Input Parameters */
> +    DSM_DEV_STATUS_VENDOR_SPECIFIC_ERROR = 4, /* Vendor Specific Error */
> +};
> +
> +/* Current revision supported by DSM specification is 1. */
> +#define DSM_REVISION        (1)
> +
> +/*
> + * please refer to ACPI 6.0: 9.14.1 _DSM (Device Specific Method): Return
> + * Value Information:

Drop "please refer to".

> + *   if set to zero, no functions are supported (other than function zero)
> + *   for the specified UUID and Revision ID. If set to one, at least one
> + *   additional function is supported.
> + */
> +
> +/* do not support any function on root. */
> +#define ROOT_SUPPORT_FUN     (0ULL)

Needs a name that implies the comment somehow.

> +#define DIMM_SUPPORT_FUN    ((1 << DSM_FUN_IMPLEMENTED)                   \
> +                           | (1 << DSM_DEV_FUN_NAMESPACE_LABEL_SIZE)      \
> +                           | (1 << DSM_DEV_FUN_GET_NAMESPACE_LABEL_DATA)  \
> +                           | (1 << DSM_DEV_FUN_SET_NAMESPACE_LABEL_DATA))
> +

I think it's best to just drop these macros.
There's a single point of use - just add a comment there
explaining what does it mean.
You will be able to drop all _FUN_ macros too.

>  struct dsm_in {
>      uint32_t handle;
>      uint32_t revision;
> @@ -420,6 +490,11 @@ struct dsm_in {
>  } QEMU_PACKED;
>  typedef struct dsm_in dsm_in;
>  
> +struct cmd_out_implemented {
> +    uint64_t cmd_list;
> +};
> +typedef struct cmd_out_implemented cmd_out_implemented;
> +
>  struct dsm_out {
>      /* the size of buffer filled by QEMU. */
>      uint32_t len;
> @@ -434,12 +509,115 @@ nvdimm_dsm_read(void *opaque, hwaddr addr, unsigned size)
>      return 0;
>  }
>  
> +static void nvdimm_dsm_write_status(GArray *out, uint32_t status)
> +{
> +    /* status locates in the first 4 bytes in the dsm memory. */

located?

> +    assert(!out->len);

But dsm itself can be part of a bigger table.
So don't do it.

> +
> +    status = cpu_to_le32(status);
> +    g_array_append_vals(out, &status, sizeof(status));

I think this should just use the (unfortunately named)
build_append_int_noprefix. Same applied everywhere
where you add single values.

> +}
> +
> +static void nvdimm_dsm_write_root(dsm_in *in, GArray *out)
> +{
> +    uint32_t status = DSM_STATUS_NOT_SUPPORTED;
> +
> +    /* please refer to ACPI 6.0: 9.14.1 _DSM (Device Specific Method) */
> +    if (in->function == DSM_FUN_IMPLEMENTED) {
> +        uint64_t cmd_list = cpu_to_le64(ROOT_SUPPORT_FUN);

see about about single use values.

> +
> +        g_array_append_vals(out, &cmd_list, sizeof(cmd_list));
> +        return;
> +    }
> +
> +    nvdimm_debug("Return status %#x.\n", status);
> +    nvdimm_dsm_write_status(out, status);
> +}
> +
> +static void nvdimm_dsm_write_nvdimm(dsm_in *in, GArray *out)
> +{
> +    GSList *list = nvdimm_get_plugged_device_list();
> +    NVDIMMDevice *nvdimm = nvdimm_get_device_by_handle(list, in->handle);
> +    uint32_t status = DSM_DEV_STATUS_NON_EXISTING_MEM_DEV;
> +    uint64_t cmd_list;
> +
> +    if (!nvdimm) {
> +        goto set_status_free;
> +    }
> +
> +    switch (in->function) {
> +    /* please refer to ACPI 6.0: 9.14.1 _DSM (Device Specific Method) */
> +    case DSM_FUN_IMPLEMENTED:
> +        cmd_list = cpu_to_le64(DIMM_SUPPORT_FUN);
> +        g_array_append_vals(out, &cmd_list, sizeof(cmd_list));
> +        goto free;
> +    default:
> +        status = DSM_STATUS_NOT_SUPPORTED;
> +    };
> +
> +set_status_free:
> +    nvdimm_debug("Return status %#x.\n", status);
> +    nvdimm_dsm_write_status(out, status);
> +free:
> +    g_slist_free(list);
> +}
> +
>  static void
>  nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
>  {
> +    NVDIMMState *state = opaque;
> +    MemoryRegion *dsm_ram_mr;
> +    dsm_in *in;
> +    GArray *out;
> +    void *dsm_ram_addr;

Why don't you give this the correct type? Will avoid need for casts.

> +
>      if (val != NOTIFY_VALUE) {
>          fprintf(stderr, "BUG: unexepected notify value 0x%" PRIx64, val);
>      }
> +
> +    dsm_ram_mr = memory_region_find(&state->mr, getpagesize(),
> +                                    getpagesize()).mr;
> +    dsm_ram_addr = memory_region_get_ram_ptr(dsm_ram_mr);

This needs a validity check for size.

> +
> +    /*
> +     * copy all input data to our local memory to avoid potential issue
> +     * as the dsm memory is visible to guest.

this comment doesn't help.
pls replace "potential issue" with an explanation.

> +     */
> +    in = g_malloc(memory_region_size(dsm_ram_mr));
> +    memcpy(in, dsm_ram_addr, memory_region_size(dsm_ram_mr));
> +
> +    le32_to_cpus(&in->revision);
> +    le32_to_cpus(&in->function);
> +    le32_to_cpus(&in->handle);
> +
> +    nvdimm_debug("Revision %#x Handler %#x Function %#x.\n", in->revision,
> +                 in->handle, in->function);
> +
> +    out = g_array_new(false, true /* clear */, 1);
> +
> +    if (in->revision != DSM_REVISION) {
> +        nvdimm_debug("Revision %#x is not supported, expect %#x.\n",
> +                      in->revision, DSM_REVISION);
> +        nvdimm_dsm_write_status(out, DSM_STATUS_NOT_SUPPORTED);
> +        goto exit;
> +    }
> +
> +    /* Handle 0 is reserved for NVDIMM Root Device. */
> +    if (!in->handle) {
> +        nvdimm_dsm_write_root(in, out);
> +        goto exit;
> +    }
> +
> +    nvdimm_dsm_write_nvdimm(in, out);
> +
> +exit:
> +    /* Write our output result to dsm memory. */
> +    ((dsm_out *)dsm_ram_addr)->len = out->len;
> +    memcpy(((dsm_out *)dsm_ram_addr)->data, out->data, out->len);

This breaks migration as memory is not dirtied.

address_space_write is generally preferable to change memory.

> +
> +    g_free(in);
> +    g_array_free(out, true);
> +    memory_region_unref(dsm_ram_mr);
>  }
>  
>  static const MemoryRegionOps nvdimm_dsm_ops = {
> @@ -547,7 +725,8 @@ static void build_nvdimm_devices(NVDIMMState *state, GSList *device_list,
>           */
>          BUILD_DSM_METHOD(dev, method,
>                           handle /* NVDIMM Device Handle */,
> -                         3 /* Invalid Input Parameters */,
> +                         DSM_DEV_STATUS_INVALID_PARAS, /* error code if UUID
> +                                                         is not matched. */
>                           "4309AC30-0D11-11E4-9191-0800200C9A66"
>                           /* UUID for NVDIMM Devices. */);
>  
> @@ -669,7 +848,8 @@ static void nvdimm_build_acpi_devices(NVDIMMState *state, GSList *device_list,
>       */
>      BUILD_DSM_METHOD(dev, method,
>                       0 /* 0 is reserved for NVDIMM Root Device*/,
> -                     2 /* Invalid Input Parameters */,
> +                     DSM_ROOT_DEV_STATUS_INVALID_PARAS, /* error code if
> +                                                     UUID is not matched. */
>                       "2F10E7A4-9E91-11E4-89D3-123B93F75CBA"
>                       /* UUID for NVDIMM Root Devices. */);
>  
> -- 
> 1.8.3.1