Re: [PATCH v8 19/29] KVM: s390: Use arm64 code

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] build: cross-arch C code extraction via awk breaks tooling and modularity
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commit e83a74be06a131ec905dd0c83821e6279b998572
Author: Steffen Eiden <seiden@linux.ibm.com>

KVM: s390: Use arm64 code

This commit introduces build infrastructure to extract marked sections
from ARM64 C files into generated .inc files for use in the s390 KVM
host code. It adds the copy-arm64c.awk script that searches for
ARM64_S390_COMMON markers and copies the matched code verbatim.

> diff --git a/arch/s390/kvm/arm64/copy-arm64c.awk b/arch/s390/kvm/arm64/copy-arm64c.awk
> new file mode 100644
> index 0000000000000..5561619aa70c8
> --- /dev/null
> +++ b/arch/s390/kvm/arm64/copy-arm64c.awk
> @@ -0,0 +1,72 @@
[ ... ]
> +BEGIN {
> +	# Constants
> +	start_pattern = "^#ifdef ARM64_S390_COMMON$"
> +	end_pattern = "^#endif /\\* ARM64_S390_COMMON \\*/$"

[Severity: Medium]
Does tightly coupling the s390 build to the exact source code formatting
in the arm64 tree present a maintenance burden?

Sharing architecture code via text extraction of C files violates kernel
modularity principles. It imposes a burden on ARM64 maintainers who must
now preserve s390-specific markers (ARM64_S390_COMMON) and formatting.
The established Linux kernel paradigm for cross-architecture code sharing
is to abstract common logic into standalone .c files in a shared
location (e.g., virt/kvm/).

[ ... ]
> +copying {
> +	gsub(/#include <asm\//, "#include <arm64/")
> +	gsub(/#include <uapi\/asm\//, "#include <uapi/arm64/")
> +	print
> +	next
> +}

[Severity: Medium]
Does copying C source code into a new file without emitting C preprocessor
#line directives break standard developer tooling?

Without #line directives, compiler errors, warnings, and debugger (GDB)
symbols will map to the generated .inc files instead of the original
arch/arm64 source, degrading debuggability.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260918133107.1042730-1-seiden@linux.ibm.com?part=19