linux-kernel - Re: [PATCH] ACPI:PRM: Reduce unnecessary printing to avoid the worries of regular users

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Message-ID: <CAJZ5v0hv0WKd-SXFhUgYs-Zpc+-PsSNOBu0r7L5TzJWgddtsKA@mail.gmail.com>
Date: Fri, 9 May 2025 20:44:25 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Zhu Qiyu <qiyuzhu2@....com>
Cc: rafael@...nel.org, lenb@...nel.org, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI:PRM: Reduce unnecessary printing to avoid the
 worries of regular users

On Sun, Apr 27, 2025 at 9:54 AM Zhu Qiyu <qiyuzhu2@....com> wrote:
>
> Commit 088984c8d54c ("ACPI: PRM: Find EFI_MEMORY_RUNTIME block for PRM
> handler and context") introduces non-essential printing "Failed
> to find VA for GUID: 7626C6AE-F973-429C-A91C-107D7BE298B0, PA: 0x0"
> which causes unnecessary worry for regular users.
>
> Refer to PRM Spec Section 4.1.2[1], both static data buffer address
> and ACPI parameter buffer address may be NULL if they are not needed.
> So there is no need to print out "Failed to find VA ... " to intimidate
> regular users.
>
> Link: https://uefi.org/sites/default/files/resources/Platform%20Runtime%20Mechanism%20-%20with%20legal%20notice.pdf # [1]
>
> Signed-off-by: Zhu Qiyu <qiyuzhu2@....com>
> ---
>  drivers/acpi/prmt.c | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
> index e549914a636c..fcd721559eb5 100644
> --- a/drivers/acpi/prmt.c
> +++ b/drivers/acpi/prmt.c
> @@ -72,7 +72,20 @@ struct prm_module_info {
>         struct prm_handler_info handlers[] __counted_by(handler_count);
>  };
>
> -static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa)
> +enum prm_addr_type {
> +       PRM_HANDLER_ADDR,
> +       PRM_STATIC_DATA_BUFFER_ADDR,
> +       PRM_ACPI_PARAM_BUFFER_ADDR,
> +       PRM_ADD_TYPE_MAX,
> +};
> +
> +static char *prm_addr_type_name[PRM_ADD_TYPE_MAX] = {
> +       "handler",
> +       "static data buffer",
> +       "acpi param buffer",
> +};
> +
> +static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa, enum prm_addr_type type)
>  {
>         efi_memory_desc_t *md;
>         u64 pa_offset = pa & ~PAGE_MASK;
> @@ -85,7 +98,12 @@ static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa)
>                 }
>         }
>
> -       pr_warn("Failed to find VA for GUID: %pUL, PA: 0x%llx", guid, pa);

Well, maybe just change the line above to something like:

  pr_info("VA for GUID: %pUL, PA: 0x%llx not found\n", guid, pa);

which should look less intimidating?

> +       if (type == PRM_HANDLER_ADDR)
> +               pr_warn("Failed to find %s VA for GUID: %pUL, PA: 0x%llx",
> +                       prm_addr_type_name[type], guid, pa);
> +       else
> +               pr_debug("Failed to find %s VA for GUID: %pUL, PA: 0x%llx",
> +                       prm_addr_type_name[type], guid, pa);
>
>         return 0;
>  }
> @@ -153,13 +171,16 @@ acpi_parse_prmt(union acpi_subtable_headers *header, const unsigned long end)
>
>                 guid_copy(&th->guid, (guid_t *)handler_info->handler_guid);
>                 th->handler_addr =
> -                       (void *)efi_pa_va_lookup(&th->guid, handler_info->handler_address);
> +                       (void *)efi_pa_va_lookup(&th->guid, handler_info->handler_address,
> +                                       PRM_HANDLER_ADDR);
>
>                 th->static_data_buffer_addr =
> -                       efi_pa_va_lookup(&th->guid, handler_info->static_data_buffer_address);
> +                       efi_pa_va_lookup(&th->guid, handler_info->static_data_buffer_address,
> +                                       PRM_STATIC_DATA_BUFFER_ADDR);
>
>                 th->acpi_param_buffer_addr =
> -                       efi_pa_va_lookup(&th->guid, handler_info->acpi_param_buffer_address);
> +                       efi_pa_va_lookup(&th->guid, handler_info->acpi_param_buffer_address,
> +                                       PRM_ACPI_PARAM_BUFFER_ADDR);
>
>         } while (++cur_handler < tm->handler_count && (handler_info = get_next_handler(handler_info)));
>
>
> base-commit: 9d7a0577c9db35c4cc52db90bc415ea248446472
> --
> 2.34.1
>