linux-kernel - Re: [PATCH v3] dcdbas: Add support for WSMT ACPI table

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Date:   Wed, 13 Jun 2018 11:54:45 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Stuart Hayes <stuart.w.hayes@...il.com>
Cc:     Darren Hart <dvhart@...radead.org>, Douglas_Warzecha@...l.com,
        Mario Limonciello <mario.limonciello@...l.com>,
        Jared.Dominguez@...l.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH v3] dcdbas: Add support for WSMT ACPI table

On Wed, Jun 13, 2018 at 4:24 AM, Stuart Hayes <stuart.w.hayes@...il.com> wrote:
>
> If the WSMT ACPI table is present and indicates that a fixed communication
> buffer should be used, use the firmware-specified buffer instead of
> allocating a buffer in memory for communications between the dcdbas driver
> and firmare.

Thanks for an update. My comments below.

> -       if ((pos + count) > MAX_SMI_DATA_BUF_SIZE)
> +       if ((pos + count) > max_smi_data_buf_size)
>                 return -EINVAL;

Parens are redundant, but okay, not purpose of the change.

> +               /* Calling Interface SMI

I suppose the style of the comments like
/*
 * Calling ...
...

> +                *
> +                * Provide physical address of command buffer field within
> +                * the struct smi_cmd... can't use virt_to_phys on smi_cmd
> +                * because address may be from memremap.

Wait, memremap() might return a virtual address. How we be sure that
we got still physical address here?

(Also note () when referring to functions)

> +                */
> +               smi_cmd->ebx = smi_data_buf_phys_addr +
> +                               offsetof(struct smi_cmd, command_buffer);

Btw, can it be one line (~83 character are okay for my opinion).

> +       acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt);
> +       if (!wsmt)
> +               return 0;
> +
> +       /* Check if WSMT ACPI table shows that protection is enabled */
> +       if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS)

> +           || !(wsmt->protection_flags
> +                & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION))

Better to indent like

if (... ||
 !(... & ...)

> +               return 0;
> +
> +       /* Scan for EPS (entry point structure) */
> +       for (addr = (u8 *)__va(0xf0000);
> +            addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table));

> +            addr += 1) {

This wasn't commented IIRC and changed. So, why?

-- 
With Best Regards,
Andy Shevchenko