linux-kernel - Re: [PATCHv4 12/13] acpi/hmat: Register memory side cache attributes

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Message-ID: <CAJZ5v0gu0zcyZtHv4mDioS6j4WMsz_59bYdzuGtOPXfKVNOX+g@mail.gmail.com>
Date:   Thu, 17 Jan 2019 18:42:28 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Keith Busch <keith.busch@...el.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rafael Wysocki <rafael@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCHv4 12/13] acpi/hmat: Register memory side cache attributes

On Wed, Jan 16, 2019 at 6:59 PM Keith Busch <keith.busch@...el.com> wrote:
>
> Register memory side cache attributes with the memory's node if HMAT
> provides the side cache iniformation table.
>
> Signed-off-by: Keith Busch <keith.busch@...el.com>
> ---
>  drivers/acpi/hmat/hmat.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/drivers/acpi/hmat/hmat.c b/drivers/acpi/hmat/hmat.c
> index 45e20dc677f9..9efdd0a63a79 100644
> --- a/drivers/acpi/hmat/hmat.c
> +++ b/drivers/acpi/hmat/hmat.c
> @@ -206,6 +206,7 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
>                                    const unsigned long end)
>  {
>         struct acpi_hmat_cache *cache = (void *)header;
> +       struct node_cache_attrs cache_attrs;
>         u32 attrs;
>
>         if (cache->header.length < sizeof(*cache)) {
> @@ -219,6 +220,37 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
>                 cache->memory_PD, cache->cache_size, attrs,
>                 cache->number_of_SMBIOShandles);
>
> +       cache_attrs.size = cache->cache_size;
> +       cache_attrs.level = (attrs & ACPI_HMAT_CACHE_LEVEL) >> 4;
> +       cache_attrs.line_size = (attrs & ACPI_HMAT_CACHE_LINE_SIZE) >> 16;
> +
> +       switch ((attrs & ACPI_HMAT_CACHE_ASSOCIATIVITY) >> 8) {
> +       case ACPI_HMAT_CA_DIRECT_MAPPED:
> +               cache_attrs.associativity = NODE_CACHE_DIRECT_MAP;
> +               break;
> +       case ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING:
> +               cache_attrs.associativity = NODE_CACHE_INDEXED;
> +               break;
> +       case ACPI_HMAT_CA_NONE:
> +       default:

This looks slightly odd as "default" covers the other case as well.
Maybe say what other case is covered by "default" in particular in a
comment?

> +               cache_attrs.associativity = NODE_CACHE_OTHER;
> +               break;
> +       }
> +
> +       switch ((attrs & ACPI_HMAT_WRITE_POLICY) >> 12) {
> +       case ACPI_HMAT_CP_WB:
> +               cache_attrs.write_policy = NODE_CACHE_WRITE_BACK;
> +               break;
> +       case ACPI_HMAT_CP_WT:
> +               cache_attrs.write_policy = NODE_CACHE_WRITE_THROUGH;
> +               break;
> +       case ACPI_HMAT_CP_NONE:
> +       default:

And analogously here.

> +               cache_attrs.write_policy = NODE_CACHE_WRITE_OTHER;
> +               break;
> +       }
> +
> +       node_add_cache(pxm_to_node(cache->memory_PD), &cache_attrs);
>         return 0;
>  }
>
> --