[PATCH 0/2] kernel: add new infrastructure for platform_has() support

Juergen Gross
2022-04-26T13:40:37Z

In another patch series [1] the need has come up to have support for
a generic feature flag infrastructure.

This patch series is introducing that infrastructure and adds the first
use case.

I have decided to use a similar interface as the already known x86
cpu_has() function. As the new infrastructure is meant to be usable for
general and arch-specific feature flags, the flags are being spread
between a general bitmap and an arch specific one.

The bitmaps start all being zero, single features can be set or reset
at any time by using the related platform_[re]set_feature() functions.

The platform_has() function is using a simple test_bit() call for now,
further optimization might be added when needed.

[1]: https://lore.kernel.org/lkml/1650646263-22047-1-git-send-email-olekstysh@gmail.com/T/#t

Juergen Gross (2):
kernel: add platform_has() infrastructure
virtio: replace arch_has_restricted_virtio_memory_access()

MAINTAINERS | 8 +++++++
arch/s390/Kconfig | 1 -
arch/s390/mm/init.c | 13 +++--------
arch/x86/Kconfig | 1 -
arch/x86/kernel/cpu/mshyperv.c | 5 ++++-
arch/x86/mm/mem_encrypt.c | 6 ------
arch/x86/mm/mem_encrypt_identity.c | 5 +++++
drivers/virtio/Kconfig | 6 ------
drivers/virtio/virtio.c | 5 ++---
include/asm-generic/Kbuild | 1 +
include/asm-generic/platform-feature.h | 8 +++++++
include/linux/platform-feature.h | 30 ++++++++++++++++++++++++++
include/linux/virtio_config.h | 9 --------
kernel/Makefile | 2 +-
kernel/platform-feature.c | 7 ++++++
15 files changed, 69 insertions(+), 38 deletions(-)
create mode 100644 include/asm-generic/platform-feature.h
create mode 100644 include/linux/platform-feature.h
create mode 100644 kernel/platform-feature.c

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2.34.1