On 01.12.2025 07:57, Penny, Zheng wrote: > [Public] > >> -----Original Message----- >> From: Jan Beulich <[email protected]> >> Sent: Tuesday, November 25, 2025 2:39 PM >> To: Penny, Zheng <[email protected]>; Andrew Cooper >> <[email protected]> >> Cc: Huang, Ray <[email protected]>; [email protected]; Roger >> Pau Monné <[email protected]>; Anthony PERARD >> <[email protected]>; Juergen Gross <[email protected]>; xen- >> [email protected] >> Subject: Re: [PATCH v4 02/24] xen: consolidate cpuid library >> >> On 21.11.2025 11:57, Penny Zheng wrote: >>> There are some cpuid library functions only referenced in >>> XEN_DOMCTL_get{,set}_cpu_policy-case, and shall be wrapped with >>> CONFIG_MGMT_HYPERCALLS later, otherwise they will become unreachable >>> when MGMT_HYPERCALLS=n, and hence violate Misra 2.1 >>> - x86_cpu_policy_clear_out_of_range_leaves >>> - zero_leaves >>> - x86_cpuid_copy_to_buffer >>> - copy_leaf_to_buffer >>> - x86_cpuid_copy_from_buffer >>> We seperate these functions by moving other functions to a new file >>> named cpuid-generic.c, and modify related Makefile-s to retain same >>> behavior. >>> >>> Signed-off-by: Penny Zheng <[email protected]> >>> --- >>> v3 -> v4: >>> - new commit >>> --- >>> tools/fuzz/cpu-policy/Makefile | 2 +- >>> tools/fuzz/x86_instruction_emulator/Makefile | 10 +- >>> tools/libs/guest/Makefile.common | 2 +- >>> tools/tests/cpu-policy/Makefile | 2 +- >>> tools/tests/x86_emulator/Makefile | 2 +- >>> xen/lib/x86/Makefile | 1 + >>> xen/lib/x86/cpuid-generic.c | 273 +++++++++++++++++++ >>> xen/lib/x86/cpuid.c | 260 ------------------ >>> 8 files changed, 283 insertions(+), 269 deletions(-) create mode >>> 100644 xen/lib/x86/cpuid-generic.c >> >> Andrew - what's your take on such a split? Personally I'm not overly happy >> to see >> related functions be scattered across two files. The separation also feels >> pretty >> random, posing the risk that later some of the code may need to move back. >> > > Right now, I could not think a better way to guard > x86_cpuid_copy_from{,to}_buffer with MGMT_HYPERCALLS without split, any > better suggestion? Or maybe I could add up some explanations on the file > cpuid_generic.c head note to explain the diffs between itself and cpuid.c, > something like: > ``` > The difference between cpuid.c and cpuid_generic.c is that the former > contains library functions that has only been referenced in management > hypercalls, such as sysctl, domctl, etc. See comment for MGMT_HYPERCALLS. > ```
If one of the files is to have only MGMT_HYPERCALLS related stuff (and if, prior to that, using #ifdef-ary in the existing file was proven unwieldy), then imo the more "natural" split would be to have a separate cpuid-mgmt.c file, where then from its name alone it already becomes halfway clear what it to live there. Another option might be to properly library-fy the copy-in and copy-out functions, one per source file, and then referenced by lib-y (or lib-$(CONFIG_...)) from the Makefile. Jan
