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Date:   Thu, 10 Nov 2022 22:08:44 +0100
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Subject: Re: [PATCH v2 08/14] platform/x86/intel/ifs: Add metadata support
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To:     Jithu Joseph <jithu.joseph@intel.com>, markgross@kernel.org
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        gregkh@linuxfoundation.org, ashok.raj@intel.com,
        tony.luck@intel.com, linux-kernel@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, patches@lists.linux.dev,
        ravi.v.shankar@intel.com, thiago.macieira@intel.com,
        athenas.jimenez.gonzalez@intel.com, sohil.mehta@intel.com
References: <20221021203413.1220137-1-jithu.joseph@intel.com>
 <20221107225323.2733518-1-jithu.joseph@intel.com>
 <20221107225323.2733518-9-jithu.joseph@intel.com>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20221107225323.2733518-9-jithu.joseph@intel.com>
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Hi,

On 11/7/22 23:53, Jithu Joseph wrote:
> From: Ashok Raj <ashok.raj@intel.com>
> 
> One of the existing reserved fields in microcode header has been
> allocated to indicate the size for metadata structures.
> 
> The metadata section within microcode header is as shown below:
> 
>     Microcode Format
>    +----------------------+  Base
>    |Header Version        |
>    +----------------------+
>    |Update revision       |
>    +----------------------+
>    |Date DDMMYYYY         |
>    +----------------------+
>    |Sig                   |
>    +----------------------+
>    |Checksum              |
>    +----------------------+
>    |Loader Version        |
>    +----------------------+
>    |Processor Flags       |
>    +----------------------+
>    |Data Size             |
>    +----------------------+
>    |Total Size            |
>    +----------------------+
>    |Meta Size             |
>    +----------------------+
>    |Reserved              |
>    +----------------------+
>    |Reserved              |
>    +----------------------+  Base+48
>    |                      |
>    |                      |
>    |                      |
>    |                      |
>    |    Microcode         |
>    |                      |
>    |     Data             |
>    |                      |
>    |                      |
>    +----------------------+  Base+48+data_size-
>    |                      |     meta_size
>    |   Meta Data          |
>    |   structure(s)       |
>    |                      |
>    +----------------------+  Base+48+data_size
>    |   Extended Signature |
>    |        Table         |
>    |                      |
>    |                      |
>    |                      |
>    |                      |
>    |                      |
>    +----------------------+  Base+total_size
> 
> Add an accessor function which will return a pointer to the
> start of a specific meta_type being queried.
> 
> In subsequent patches, IFS test image file (which reuse microcode header
> format) will make use of metadata section.
> 
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans


> ---
>  drivers/platform/x86/intel/ifs/load.c | 32 +++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
> index 89ce265887ea..60ba5a057f91 100644
> --- a/drivers/platform/x86/intel/ifs/load.c
> +++ b/drivers/platform/x86/intel/ifs/load.c
> @@ -44,6 +44,38 @@ static const char * const scan_authentication_status[] = {
>  	[2] = "Chunk authentication error. The hash of chunk did not match expected value"
>  };
>  
> +#define META_TYPE_END		(0)
> +
> +struct metadata_header {
> +	unsigned int		type;
> +	unsigned int		blk_size;
> +};
> +
> +static struct metadata_header *ifs_find_meta_data(void *ucode, unsigned int meta_type)
> +{
> +	struct metadata_header *meta_header;
> +	unsigned long data_size, total_meta;
> +	unsigned long meta_size = 0;
> +
> +	data_size = get_datasize(ucode);
> +	total_meta = ((struct microcode_intel *)ucode)->hdr.metasize;
> +
> +	if (!total_meta)
> +		return NULL;
> +
> +	meta_header = (ucode + MC_HEADER_SIZE + data_size) - total_meta;
> +
> +	while ((meta_header->type != META_TYPE_END) && meta_header->blk_size &&
> +	       meta_size < total_meta) {
> +		meta_size += meta_header->blk_size;
> +		if (meta_header->type == meta_type)
> +			return meta_header;
> +
> +		meta_header = (void *)meta_header + meta_header->blk_size;
> +	}
> +	return NULL;
> +}
> +
>  /*
>   * To copy scan hashes and authenticate test chunks, the initiating cpu must point
>   * to the EDX:EAX to the test image in linear address.