RE: [PATCH v1] Export Runtime Configuration Interface table to sysfs

[<Mario.Limonciello@dell.com>]

> -----Original Message-----
> From: K, Narendra
> Sent: Wednesday, July 10, 2019 11:59 AM
> To: linux-efi@vger.kernel.org; ard.biesheuvel@linaro.org; pjones@redhat.com
> Cc: K, Narendra; Hayes, Stuart; Limonciello, Mario
> Subject: [PATCH v1] Export Runtime Configuration Interface table to sysfs
> 
> From: Narendra K <Narendra.K@dell.com>
> 
> System firmware advertises the address of the 'Runtime Configuration Interface
> table version 2 (RCI2)' via an EFI Configuration Table entry. This code retrieves
> the RCI2 table from the address and exports it to sysfs as a binary attribute 'rci2'
> under /sys/firmware/efi/tables directory.
> The approach adopted is similar to the attribute 'DMI' under
> /sys/firmware/dmi/tables.
> 
> RCI2 table contains BIOS HII in XML format and is used to populate BIOS setup
> page in Dell EMC OpenManage Server Administrator tool.
> The BIOS setup page contains BIOS tokens which can be configured.
> 
> Signed-off-by: Narendra K <Narendra.K@dell.com>

Reviewed-by: Mario Limonciello <mario.limonciello@dell.com>

> ---
> Hi Ard, the review comment in the v0 version of the patch suggested that the
> kconfig symbol be set to Y for X86. I made a change to the suggestion.
> In the v1 version, I have set the symbol to N by default and added a note to the
> help section to make it Y for Dell EMC PowerEdge systems. If it needs to be
> changed, I will resubmit the patch after changing it to implement the suggestion.
> 
> The patch is created on 'next' branch of efi tree.
> 
> v0 -> v1:
> - Introduced a new Kconfig symbol CONFIG_EFI_RCI2_TABLE and compile
> RCI2 table support if it is set. Set the symbol to N by default.
> - Removed calling 'efi_rci2_sysfs_init' from drivers/firmware/efi/efi.c and made
> it a 'late_initcall' in drivers/firmware/efi/rci2_table.c.
> Removed the function declaration from include/linux/efi.h.
> 
> RFC -> v0:
> - Removed rci2 table from struct efi and defined it in rci2_table.c similar to the
> way uv_systab_phys is defined in arch/x86/platform/uv/bios_uv.c
> - Removed the oem_tables array and added rci2 to common_tables array
> - Removed the string 'rci2' from the common_tables array so that it is not
> printed in dmesg.
> - Merged function 'efi_rci2_table_init' into 'efi_rci2_sysfs_init' function to avoid
> calling early_memremap/unmap functions.
> 
>  Documentation/ABI/testing/sysfs-firmware-efi |   8 +
>  arch/x86/platform/efi/efi.c                  |   3 +
>  drivers/firmware/efi/Kconfig                 |  15 ++
>  drivers/firmware/efi/Makefile                |   1 +
>  drivers/firmware/efi/efi.c                   |   3 +
>  drivers/firmware/efi/rci2_table.c            | 147 +++++++++++++++++++
>  include/linux/efi.h                          |   9 ++
>  7 files changed, 186 insertions(+)
>  create mode 100644 drivers/firmware/efi/rci2_table.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-firmware-efi
> b/Documentation/ABI/testing/sysfs-firmware-efi
> index e794eac32a90..5e4d0b27cdfe 100644
> --- a/Documentation/ABI/testing/sysfs-firmware-efi
> +++ b/Documentation/ABI/testing/sysfs-firmware-efi
> @@ -28,3 +28,11 @@ Description:	Displays the physical addresses of all
> EFI Configuration
>  		versions are always printed first, i.e. ACPI20 comes
>  		before ACPI.
>  Users:		dmidecode
> +
> +What:		/sys/firmware/efi/tables/rci2
> +Date:		July 2019
> +Contact:	Narendra K <Narendra.K@dell.com>, linux-bugs@dell.com
> +Description:	Displays the content of the Runtime Configuration Interface
> +		Table version 2 on Dell EMC PowerEdge systems in binary
> format
> +Users:		It is used by Dell EMC OpenManage Server Administrator tool to
> +		populate BIOS setup page.
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index
> 6697c109c449..c202e1b07e29 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -82,6 +82,9 @@ static const unsigned long * const efi_tables[] = {
>  	&efi.esrt,
>  	&efi.properties_table,
>  	&efi.mem_attr_table,
> +#ifdef CONFIG_EFI_RCI2_TABLE
> +	&rci2_table_phys,
> +#endif
>  };
> 
>  u64 efi_setup;		/* efi setup_data physical address */
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index
> d4ea929e8b34..1e1e33b61713 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -180,6 +180,21 @@ config RESET_ATTACK_MITIGATION
>  	  have been evicted, since otherwise it will trigger even on clean
>  	  reboots.
> 
> +config EFI_RCI2_TABLE
> +	bool "EFI Runtime Configuration Interface Table Version 2 Support"
> +	depends on EFI
> +	default n
> +	help
> +	  Displays the content of the Runtime Configuration Interface
> +	  Table version 2 on Dell EMC PowerEdge systems as a binary
> +	  attribute 'rci2' under /sys/firmware/efi/tables directory.
> +
> +	  RCI2 table contains BIOS HII in XML format and is used to populate
> +	  BIOS setup page in Dell EMC OpenManage Server Administrator tool.
> +	  The BIOS setup page contains BIOS tokens which can be configured.
> +
> +	  Say Y here for Dell EMC PowerEdge systems.
> +
>  endmenu
> 
>  config UEFI_CPER
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index
> d2d0d2030620..2693f291a950 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -25,6 +25,7 @@ obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+=
> efibc.o
>  obj-$(CONFIG_EFI_TEST)			+= test/
>  obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o
>  obj-$(CONFIG_APPLE_PROPERTIES)		+= apple-properties.o
> +obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2_table.o
> 
>  arm-obj-$(CONFIG_EFI)			:= arm-init.o arm-runtime.o
>  obj-$(CONFIG_ARM)			+= $(arm-obj-y)
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index
> d082d5b2fb84..d01b05c1ee49 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -463,6 +463,9 @@ static __initdata efi_config_table_type_t
> common_tables[] = {
>  	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
>  	{LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
>  	{LINUX_EFI_MEMRESERVE_TABLE_GUID, "MEMRESERVE",
> &efi.mem_reserve},
> +#ifdef CONFIG_EFI_RCI2_TABLE
> +	{DELLEMC_EFI_RCI2_TABLE_GUID, NULL, &rci2_table_phys}, #endif
>  	{NULL_GUID, NULL, NULL},
>  };
> 
> diff --git a/drivers/firmware/efi/rci2_table.c b/drivers/firmware/efi/rci2_table.c
> new file mode 100644
> index 000000000000..3e290f96620a
> --- /dev/null
> +++ b/drivers/firmware/efi/rci2_table.c
> @@ -0,0 +1,147 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Export Runtime Configuration Interface Table Version 2 (RCI2)
> + * to sysfs
> + *
> + * Copyright (C) 2019 Dell Inc
> + * by Narendra K <Narendra.K@dell.com>
> + *
> + * System firmware advertises the address of the RCI2 Table via
> + * an EFI Configuration Table entry. This code retrieves the RCI2
> + * table from the address and exports it to sysfs as a binary
> + * attribute 'rci2' under /sys/firmware/efi/tables directory.
> + */
> +
> +#include <linux/kobject.h>
> +#include <linux/device.h>
> +#include <linux/sysfs.h>
> +#include <linux/efi.h>
> +#include <linux/types.h>
> +#include <linux/io.h>
> +
> +#define RCI_SIGNATURE	"_RC_"
> +
> +struct rci2_table_global_hdr {
> +	u16 type;
> +	u16 resvd0;
> +	u16 hdr_len;
> +	u8 rci2_sig[4];
> +	u16 resvd1;
> +	u32 resvd2;
> +	u32 resvd3;
> +	u8 major_rev;
> +	u8 minor_rev;
> +	u16 num_of_structs;
> +	u32 rci2_len;
> +	u16 rci2_chksum;
> +} __packed;
> +
> +static u8 *rci2_base;
> +static u32 rci2_table_len;
> +unsigned long rci2_table_phys __ro_after_init = EFI_INVALID_TABLE_ADDR;
> +
> +static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
> +			      struct bin_attribute *attr, char *buf,
> +			      loff_t pos, size_t count)
> +{
> +	memcpy(buf, attr->private + pos, count);
> +	return count;
> +}
> +
> +static BIN_ATTR(rci2, S_IRUSR, raw_table_read, NULL, 0);
> +
> +static u16 checksum(void)
> +{
> +	u8 len_is_odd = rci2_table_len % 2;
> +	u32 chksum_len = rci2_table_len;
> +	u16 *base = (u16 *)rci2_base;
> +	u8 buf[2] = {0};
> +	u32 offset = 0;
> +	u16 chksum = 0;
> +
> +	if (len_is_odd)
> +		chksum_len -= 1;
> +
> +	while (offset < chksum_len) {
> +		chksum += *base;
> +		offset += 2;
> +		base++;
> +	}
> +
> +	if (len_is_odd) {
> +		buf[0] = *(u8 *)base;
> +		chksum += *(u16 *)(buf);
> +	}
> +
> +	return chksum;
> +}
> +
> +int __init efi_rci2_sysfs_init(void)
> +{
> +	struct kobject *tables_kobj;
> +	int ret = -ENOMEM;
> +
> +	rci2_base = memremap(rci2_table_phys,
> +			     sizeof(struct rci2_table_global_hdr),
> +			     MEMREMAP_WB);
> +	if (!rci2_base) {
> +		pr_debug("RCI2 table init failed - could not map RCI2 table\n");
> +		goto err;
> +	}
> +
> +	if (strncmp(rci2_base +
> +		    offsetof(struct rci2_table_global_hdr, rci2_sig),
> +		    RCI_SIGNATURE, 4)) {
> +		pr_debug("RCI2 table init failed - incorrect signature\n");
> +		ret = -ENODEV;
> +		goto err_unmap;
> +	}
> +
> +	rci2_table_len = *(u32 *)(rci2_base +
> +				  offsetof(struct rci2_table_global_hdr,
> +				  rci2_len));
> +
> +	memunmap(rci2_base);
> +
> +	if (!rci2_table_len) {
> +		pr_debug("RCI2 table init failed - incorrect table length\n");
> +		goto err;
> +	}
> +
> +	rci2_base = memremap(rci2_table_phys, rci2_table_len,
> MEMREMAP_WB);
> +	if (!rci2_base) {
> +		pr_debug("RCI2 table - could not map RCI2 table\n");
> +		goto err;
> +	}
> +
> +	if (checksum() != 0) {
> +		pr_debug("RCI2 table - incorrect checksum\n");
> +		ret = -ENODEV;
> +		goto err_unmap;
> +	}
> +
> +	tables_kobj = kobject_create_and_add("tables", efi_kobj);
> +	if (!tables_kobj) {
> +		pr_debug("RCI2 table - tables_kobj creation failed\n");
> +		goto err_unmap;
> +	}
> +
> +	bin_attr_rci2.size = rci2_table_len;
> +	bin_attr_rci2.private = rci2_base;
> +	ret = sysfs_create_bin_file(tables_kobj, &bin_attr_rci2);
> +	if (ret != 0) {
> +		pr_debug("RCI2 table - rci2 sysfs bin file creation failed\n");
> +		kobject_del(tables_kobj);
> +		kobject_put(tables_kobj);
> +		goto err_unmap;
> +	}
> +
> +	return 0;
> +
> + err_unmap:
> +	memunmap(rci2_base);
> + err:
> +	pr_debug("RCI2 table - sysfs initialization failed\n");
> +	return ret;
> +}
> +late_initcall(efi_rci2_sysfs_init);
> diff --git a/include/linux/efi.h b/include/linux/efi.h index
> ac48db107214..b07c89b7cba2 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -691,6 +691,11 @@ void efi_native_runtime_setup(void);
>  #define LINUX_EFI_TPM_EVENT_LOG_GUID		EFI_GUID(0xb7799cb0,
> 0xeca2, 0x4943,  0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa)
>  #define LINUX_EFI_MEMRESERVE_TABLE_GUID		EFI_GUID(0x888eb0c6,
> 0x8ede, 0x4ff5,  0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2)
> 
> +#ifdef CONFIG_EFI_RCI2_TABLE
> +/* OEM GUIDs */
> +#define DELLEMC_EFI_RCI2_TABLE_GUID		EFI_GUID(0x2d9f28a2,
> 0xa886, 0x456a,  0x97, 0xa8, 0xf1, 0x1e, 0xf2, 0x4f, 0xf4, 0x55)
> +#endif
> +
>  typedef struct {
>  	efi_guid_t guid;
>  	u64 table;
> @@ -1703,6 +1708,10 @@ struct linux_efi_tpm_eventlog {
> 
>  extern int efi_tpm_eventlog_init(void);
> 
> +#ifdef CONFIG_EFI_RCI2_TABLE
> +extern unsigned long rci2_table_phys;
> +#endif
> +
>  /*
>   * efi_runtime_service() function identifiers.
>   * "NONE" is used by efi_recover_from_page_fault() to check if the page
> --
> 2.18.1
> 
> --
> With regards,
> Narendra K