Re: [RFC 03/10] platform/x86/intel/ifs: Add driver for In-Field Scan

["Williams, Dan J" <dan.j.williams@intel.com>]

On Tue, 2022-03-01 at 11:54 -0800, Jithu Joseph wrote:
> In-Field Scan (IFS) provides hardware hooks to perform core tests and
> report failures for portions of silicon that lack error detection
> capabilities, which will be available in some server SKUs starting with
> Sapphire Rapids. It offers infrastructure to specific users such as cloud
> providers or OEMs to schedule tests and find in-field failures due to aging
> in silicon that might not necessarily be reported with normal machine
> checks.
> 
> Add basic parts of the IFS module (initialization and check IFS capability
> support in a processor).
> 
> MSR IA32_CORE_CAPABILITY is a feature-enumerating MSR, bit 2 of which
> reports MSR_INTEGRITY_CAPABILITIES. Processor that supports IFS
> should reports the MSR_INTEGRITY_CAPABILITIES enabled.
> 
> Please check the latest Intel 64 and IA-32 Architectures Software
> Developer's Manual for more detailed information on the MSR and the
> MSR_INTEGRITY_CAPABILITIES.
> 
> Originally-by: Kyung Min Park <kyung.min.park@intel.com>
> Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
> Reviewed-by: Ashok Raj <ashok.raj@intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> ---
>  MAINTAINERS                             |  7 ++++
>  drivers/platform/x86/intel/Kconfig      |  1 +
>  drivers/platform/x86/intel/Makefile     |  1 +
>  drivers/platform/x86/intel/ifs/Kconfig  |  9 +++++
>  drivers/platform/x86/intel/ifs/Makefile |  7 ++++
>  drivers/platform/x86/intel/ifs/core.c   | 49 +++++++++++++++++++++++++
>  drivers/platform/x86/intel/ifs/ifs.h    | 14 +++++++
>  7 files changed, 88 insertions(+)
>  create mode 100644 drivers/platform/x86/intel/ifs/Kconfig
>  create mode 100644 drivers/platform/x86/intel/ifs/Makefile
>  create mode 100644 drivers/platform/x86/intel/ifs/core.c
>  create mode 100644 drivers/platform/x86/intel/ifs/ifs.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 777cd6fa2b3d..4c9912c0d725 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9685,6 +9685,13 @@ B:       https://bugzilla.kernel.org
>  T:     git git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux.git
>  F:     drivers/idle/intel_idle.c
>  
> +INTEL IN FIELD SCAN (IFS) DRIVER
> +M:     Jithu Joseph <jithu.joseph@intel.com>
> +R:     Ashok Raj <ashok.raj@intel.com>
> +R:     Tony Luck <tony.luck@intel.com>
> +S:     Maintained
> +F:     drivers/platform/x86/intel/ifs
> +
>  INTEL INTEGRATED SENSOR HUB DRIVER
>  M:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
>  M:     Jiri Kosina <jikos@kernel.org>
> diff --git a/drivers/platform/x86/intel/Kconfig b/drivers/platform/x86/intel/Kconfig
> index 8e65086bb6c8..7339e7daf0a1 100644
> --- a/drivers/platform/x86/intel/Kconfig
> +++ b/drivers/platform/x86/intel/Kconfig
> @@ -4,6 +4,7 @@
>  #
>  
>  source "drivers/platform/x86/intel/atomisp2/Kconfig"
> +source "drivers/platform/x86/intel/ifs/Kconfig"
>  source "drivers/platform/x86/intel/int1092/Kconfig"
>  source "drivers/platform/x86/intel/int33fe/Kconfig"
>  source "drivers/platform/x86/intel/int3472/Kconfig"
> diff --git a/drivers/platform/x86/intel/Makefile b/drivers/platform/x86/intel/Makefile
> index 35f2066578b2..bd7f2ef5e767 100644
> --- a/drivers/platform/x86/intel/Makefile
> +++ b/drivers/platform/x86/intel/Makefile
> @@ -5,6 +5,7 @@
>  #
>  
>  obj-$(CONFIG_INTEL_ATOMISP2_PDX86)     += atomisp2/
> +obj-$(CONFIG_INTEL_IFS)                        += ifs/
>  obj-$(CONFIG_INTEL_SAR_INT1092)                += int1092/
>  obj-$(CONFIG_INTEL_CHT_INT33FE)                += int33fe/
>  obj-$(CONFIG_INTEL_SKL_INT3472)                += int3472/
> diff --git a/drivers/platform/x86/intel/ifs/Kconfig b/drivers/platform/x86/intel/ifs/Kconfig
> new file mode 100644
> index 000000000000..88e3d4fa1759
> --- /dev/null
> +++ b/drivers/platform/x86/intel/ifs/Kconfig
> @@ -0,0 +1,9 @@
> +config INTEL_IFS
> +       tristate "Intel In Field Scan"
> +       depends on X86 && 64BIT && SMP

Are there actual CONFIG_SMP and CONFIG_64BIT compilation dependencies
in this driver? It looks like this could compile without those config
dependencies.

> +       help
> +         Enable support for In Field Scan in Intel CPU to perform core
> +         logic test in the field. To compile this driver as a module, choose
> +         M here. The module will be called intel_ifs.
> +
> +         If unsure, say N.
> diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
> new file mode 100644
> index 000000000000..05b4925402b4
> --- /dev/null
> +++ b/drivers/platform/x86/intel/ifs/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# Makefile for the In-Field Scan driver
> +#
> +
> +obj-$(CONFIG_INTEL_IFS)                        += intel_ifs.o
> +
> +intel_ifs-objs                         := core.o
> diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
> new file mode 100644
> index 000000000000..fb3c864d3085
> --- /dev/null
> +++ b/drivers/platform/x86/intel/ifs/core.c
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2021 Intel Corporation.
> + *
> + * Author: Jithu Joseph <jithu.joseph@intel.com>

I don't see any need to include author info in source files, that's
what 'git blame' is for.

> + */
> +
> +#include <linux/module.h>
> +#include <asm/cpu_device_id.h>
> +
> +#include "ifs.h"
> +
> +#define X86_MATCH(model)                                       \
> +       X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6,            \
> +               INTEL_FAM6_##model, X86_FEATURE_CORE_CAPABILITIES, NULL)
> +
> +static const struct x86_cpu_id ifs_cpu_ids[] __initconst = {
> +       X86_MATCH(SAPPHIRERAPIDS_X),
> +       {}
> +};
> +
> +MODULE_DEVICE_TABLE(x86cpu, ifs_cpu_ids);
> +
> +static int __init ifs_init(void)
> +{
> +       const struct x86_cpu_id *m;
> +       u64 ia32_core_caps;
> +
> +       /* ifs capability check */
> +       m = x86_match_cpu(ifs_cpu_ids);
> +       if (!m)
> +               return -ENODEV;
> +       if (rdmsrl_safe(MSR_IA32_CORE_CAPS, &ia32_core_caps))
> +               return -ENODEV;
> +       if (!(ia32_core_caps & MSR_IA32_CORE_CAPS_INTEGRITY))
> +               return -ENODEV;
> +
> +       return 0;
> +}
> +
> +static void __exit ifs_exit(void)
> +{
> +       pr_info("unloaded 'In-Field Scan' module\n");
> +}
> +
> +MODULE_LICENSE("GPL");
> +MODULE_INFO(name, "ifs");
> +MODULE_DESCRIPTION("ifs");

Just omit MODULE_INFO and MODULE_DESCRIPTION if nothing of importance
needs to be added.

> +module_init(ifs_init);
> +module_exit(ifs_exit);
> diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
> new file mode 100644
> index 000000000000..f3f924fced06
> --- /dev/null
> +++ b/drivers/platform/x86/intel/ifs/ifs.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Copyright(c) 2021 Intel Corporation.
> + *
> + * Author: Jithu Joseph <jithu.joseph@intel.com>
> + */
> +
> +#ifndef _IFS_H_
> +#define _IFS_H_
> +
> +/* These bits are in the IA32_CORE_CAPABILITIES MSR */
> +#define MSR_IA32_CORE_CAPS_INTEGRITY_BIT       2
> +#define MSR_IA32_CORE_CAPS_INTEGRITY           BIT(MSR_IA32_CORE_CAPS_INTEGRITY_BIT)

Is this header going to grow any more definitions? Otherwise these 2
lines can just move into the source file.