linux-kernel - Re: [PATCH v4 04/10] platform/x86/intel/ifs: Read IFS firmware image

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Message-ID: <YmfNVG0qLahv7TzL@kroah.com>
Date:   Tue, 26 Apr 2022 12:45:40 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Tony Luck <tony.luck@...el.com>
Cc:     hdegoede@...hat.com, markgross@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, corbet@....net,
        andriy.shevchenko@...ux.intel.com, jithu.joseph@...el.com,
        ashok.raj@...el.com, rostedt@...dmis.org, dan.j.williams@...el.com,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, patches@...ts.linux.dev,
        ravi.v.shankar@...el.com
Subject: Re: [PATCH v4 04/10] platform/x86/intel/ifs: Read IFS firmware image

On Fri, Apr 22, 2022 at 01:02:13PM -0700, Tony Luck wrote:
> From: Jithu Joseph <jithu.joseph@...el.com>
> 
> Driver probe routine allocates structure to communicate status
> and parameters between functions in the driver. Also call
> load_ifs_binary() to load the scan image file.
> 
> There is a separate scan image file for each processor family,
> model, stepping combination. This is read from the static path:
> 
>   /lib/firmware/intel/ifs/{ff-mm-ss}.scan
> 
> Step 1 in loading is to generate the correct path and use
> request_firmware_direct() to load into memory.
> 
> Subsequent patches will use the IFS MSR interfaces to copy
> the image to BIOS reserved memory and validate the SHA256
> checksums.
> 
> Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
> Co-developed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  drivers/platform/x86/intel/ifs/Makefile |  2 +-
>  drivers/platform/x86/intel/ifs/core.c   | 36 ++++++++++++++++++++++++-
>  drivers/platform/x86/intel/ifs/ifs.h    | 25 +++++++++++++++++
>  drivers/platform/x86/intel/ifs/load.c   | 28 +++++++++++++++++++
>  4 files changed, 89 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/platform/x86/intel/ifs/ifs.h
>  create mode 100644 drivers/platform/x86/intel/ifs/load.c
> 
> diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
> index af904880e959..98b6fde15689 100644
> --- a/drivers/platform/x86/intel/ifs/Makefile
> +++ b/drivers/platform/x86/intel/ifs/Makefile
> @@ -1,3 +1,3 @@
>  obj-$(CONFIG_INTEL_IFS)		+= intel_ifs.o
>  
> -intel_ifs-objs			:= core.o
> +intel_ifs-objs			:= core.o load.o
> diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
> index 5713e6ee90f0..ed4ded6755b2 100644
> --- a/drivers/platform/x86/intel/ifs/core.c
> +++ b/drivers/platform/x86/intel/ifs/core.c
> @@ -6,6 +6,8 @@
>  
>  #include <asm/cpu_device_id.h>
>  
> +#include "ifs.h"
> +
>  enum test_types {
>  	IFS_SAF,
>  };
> @@ -20,10 +22,27 @@ static const struct x86_cpu_id ifs_cpu_ids[] __initconst = {
>  };
>  MODULE_DEVICE_TABLE(x86cpu, ifs_cpu_ids);
>  
> +static struct ifs_device ifs_devices[] = {
> +	[IFS_SAF] = {
> +		.data = {
> +			.integrity_cap_bit = MSR_INTEGRITY_CAPS_PERIODIC_BIST_BIT,
> +		},
> +		.misc = {
> +			.name = "intel_ifs_0",
> +			.nodename = "intel_ifs/0",
> +			.minor = MISC_DYNAMIC_MINOR,
> +		},
> +	},
> +};
> +
> +#define IFS_NUMTESTS ARRAY_SIZE(ifs_devices)

Cute way to do this, but I don't see you ever have any more devices
added to this list in this series.  Did I miss them?

If not, why all the overhead and complexity involved here for just a
single misc device?

thanks,

greg k-h