Re: [PATCH v2] x86/hyperv: Reserve 3 interrupt vectors used exclusively by mshv

From: kernel test robot

Date: Wed Feb 18 2026 - 07:36:01 EST


Hi Mukesh,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/x86/core]
[also build test WARNING on linus/master v6.19 next-20260217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Mukesh-R/x86-hyperv-Reserve-3-interrupt-vectors-used-exclusively-by-mshv/20260218-071406
base: tip/x86/core
patch link: https://lore.kernel.org/r/20260217231158.1184736-1-mrathor%40linux.microsoft.com
patch subject: [PATCH v2] x86/hyperv: Reserve 3 interrupt vectors used exclusively by mshv
config: x86_64-rhel-9.4 (https://download.01.org/0day-ci/archive/20260218/202602182000.O5dSFVVd-lkp@xxxxxxxxx/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260218/202602182000.O5dSFVVd-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602182000.O5dSFVVd-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> arch/x86/kernel/cpu/mshyperv.c:485:13: warning: 'hv_reserve_irq_vectors' defined but not used [-Wunused-function]
485 | static void hv_reserve_irq_vectors(void)
| ^~~~~~~~~~~~~~~~~~~~~~


vim +/hv_reserve_irq_vectors +485 arch/x86/kernel/cpu/mshyperv.c

480
481 /*
482 * Reserve vectors hard coded in the hypervisor. If used outside, the hypervisor
483 * will either crash or hang or attempt to break into debugger.
484 */
> 485 static void hv_reserve_irq_vectors(void)
486 {
487 #define HYPERV_DBG_FASTFAIL_VECTOR 0x29
488 #define HYPERV_DBG_ASSERT_VECTOR 0x2C
489 #define HYPERV_DBG_SERVICE_VECTOR 0x2D
490
491 if (cpu_feature_enabled(X86_FEATURE_FRED))
492 return;
493
494 if (test_and_set_bit(HYPERV_DBG_ASSERT_VECTOR, system_vectors) ||
495 test_and_set_bit(HYPERV_DBG_SERVICE_VECTOR, system_vectors) ||
496 test_and_set_bit(HYPERV_DBG_FASTFAIL_VECTOR, system_vectors))
497 BUG();
498
499 pr_info("Hyper-V:reserve vectors: %d %d %d\n", HYPERV_DBG_ASSERT_VECTOR,
500 HYPERV_DBG_SERVICE_VECTOR, HYPERV_DBG_FASTFAIL_VECTOR);
501 }
502

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https://github.com/intel/lkp-tests/wiki