powerpc: Stop using of_root

Replace all usages of of_root by of_find_node_by_path("/")

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214103152.12269-5-mpe@ellerman.id.au

powerpc/pseries: Detect secure and trusted boot state of the system.

The device-tree properties to check secure and trusted boot state are
different for guests (pseries) compared to baremetal (powernv).

This patch updates the existing is_ppc_secureboot_enabled() and
is_ppc_trustedboot_enabled() functions to add support for pseries.

For pseries the secureboot and trustedboot state are exposed via
device-tree properties /ibm,secure-boot and /ibm,trusted-boot.

The values of ibm,secure-boot under pseries are interpreted as:

0 - Disabled
1 - Enabled in Log-only mode. This patch interprets this value as
disabled, since audit mode is currently not supported for
Linux.
2 - Enabled and enforced.
3-9 - Enabled and enforcing; requirements are at the discretion of
the operating system.

The values of ibm,trusted-boot under pseries are interpreted as:
0 - Disabled
1 - Enabled

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
[mpe: Drop machdep.h inclusion, tweak change log slightly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594813921-12425-1-git-send-email-nayna@linux.ibm.com

powerpc: Detect the trusted boot state of the system

While secure boot permits only properly verified signed kernels to be
booted, trusted boot calculates the file hash of the kernel image and
stores the measurement prior to boot, that can be subsequently
compared against good known values via attestation services.

This patch reads the trusted boot state of a PowerNV system. The state
is used to conditionally enable additional measurement rules in the
IMA arch-specific policies.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Eric Richter <erichte@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e9eeee6b-b9bf-1e41-2954-61dbd6fbfbcf@linux.ibm.com

powerpc: Detect the secure boot mode of the system

This patch defines a function to detect the secure boot state of a
PowerNV system.

The PPC_SECURE_BOOT config represents the base enablement of secure
boot for powerpc.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Eric Richter <erichte@linux.ibm.com>
[mpe: Fold in change from Nayna to add "ibm,secureboot" to ids]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/46b003b9-3225-6bf7-9101-ed6580bb748c@linux.ibm.com