On Sat, Mar 01, 2025 at 09:23:51AM +0200, Mike Rapoport wrote:

Hi Brendan,

On Fri, Jan 10, 2025 at 06:40:28PM +0000, Brendan Jackman wrote:

quoted

Currently a nop config. Keeping as a separate commit for easy review of
the boring bits. Later commits will use and enable this new config.

This config is only added for non-UML x86_64 as other architectures do
not yet have pending implementations. It also has somewhat artificial
dependencies on !PARAVIRT and !KASAN which are explained in the Kconfig
file.

Co-developed-by: Junaid Shahid <redacted>
Signed-off-by: Junaid Shahid <redacted>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/alpha/include/asm/Kbuild      |  1 +
 arch/arc/include/asm/Kbuild        |  1 +
 arch/arm/include/asm/Kbuild        |  1 +
 arch/arm64/include/asm/Kbuild      |  1 +
 arch/csky/include/asm/Kbuild       |  1 +
 arch/hexagon/include/asm/Kbuild    |  1 +
 arch/loongarch/include/asm/Kbuild  |  3 +++
 arch/m68k/include/asm/Kbuild       |  1 +
 arch/microblaze/include/asm/Kbuild |  1 +
 arch/mips/include/asm/Kbuild       |  1 +
 arch/nios2/include/asm/Kbuild      |  1 +
 arch/openrisc/include/asm/Kbuild   |  1 +
 arch/parisc/include/asm/Kbuild     |  1 +
 arch/powerpc/include/asm/Kbuild    |  1 +
 arch/riscv/include/asm/Kbuild      |  1 +
 arch/s390/include/asm/Kbuild       |  1 +
 arch/sh/include/asm/Kbuild         |  1 +
 arch/sparc/include/asm/Kbuild      |  1 +
 arch/um/include/asm/Kbuild         |  2 +-
 arch/x86/Kconfig                   | 14 ++++++++++++++
 arch/xtensa/include/asm/Kbuild     |  1 +
 include/asm-generic/asi.h          |  5 +++++
 22 files changed, 41 insertions(+), 1 deletion(-)

I don't think this all is needed. You can put asi.h with stubs used outside
of arch/x86 in include/linux and save you the hassle of updating every
architecture.

...

If you expect other architectures might implement ASI the config would better
fit into init/Kconfig or mm/Kconfig and in arch/x86/Kconfig will define
ARCH_HAS_MITIGATION_ADDRESS_SPACE_ISOLATION.

...

quoted

+++ b/include/asm-generic/asi.h

@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_ASI_H
+#define __ASM_GENERIC_ASI_H
+
+#endif

IMHO it should be include/linux/asi.h, with something like

#infdef __LINUX_ASI_H
#define __LINUX_ASI_H

#ifdef CONFIG_MITIGATION_ADDRESS_SPACE_ISOLATION

#include <asm/asi.h>

#else /* CONFIG_MITIGATION_ADDRESS_SPACE_ISOLATION */

/* stubs for functions used outside arch/ */

#endif /* CONFIG_MITIGATION_ADDRESS_SPACE_ISOLATION */

#endif /* __LINUX_ASI_H */

Thanks Mike! That does indeed look way tidier. I'll try to adopt it.