Re: [PATCH v3 1/4] arm64: KVM: use mutex_trylock_nest_lock when locking all vCPUs

[kernel test robot <lkp@intel.com>]

Hi Maxim,

kernel test robot noticed the following build errors:

[auto build test ERROR on kvm/queue]
[also build test ERROR on kvm/next kvmarm/next tip/locking/core linus/master v6.15-rc5 next-20250507]
[cannot apply to kvm/linux-next]
[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/Maxim-Levitsky/arm64-KVM-use-mutex_trylock_nest_lock-when-locking-all-vCPUs/20250501-042643
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
patch link:    https://lore.kernel.org/r/20250430202311.364641-2-mlevitsk%40redhat.com
patch subject: [PATCH v3 1/4] arm64: KVM: use mutex_trylock_nest_lock when locking all vCPUs
config: x86_64-rhel-9.4 (https://download.01.org/0day-ci/archive/20250508/202505080024.CZZ0ssB5-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250508/202505080024.CZZ0ssB5-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505080024.CZZ0ssB5-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_trylock_all_vcpus':
>> arch/x86/kvm/../../../virt/kvm/kvm_main.c:1381:22: error: implicit declaration of function 'mutex_trylock_nest_lock'; did you mean 'mutex_lock_nest_lock'? [-Werror=implicit-function-declaration]
    1381 |                 if (!mutex_trylock_nest_lock(&vcpu->mutex, &kvm->lock))
         |                      ^~~~~~~~~~~~~~~~~~~~~~~
         |                      mutex_lock_nest_lock
   cc1: some warnings being treated as errors


vim +1381 arch/x86/kvm/../../../virt/kvm/kvm_main.c

  1370	
  1371	/*
  1372	 * Try to lock all of the VM's vCPUs.
  1373	 * Assumes that the kvm->lock is held.
  1374	 */
  1375	int kvm_trylock_all_vcpus(struct kvm *kvm)
  1376	{
  1377		struct kvm_vcpu *vcpu;
  1378		unsigned long i, j;
  1379	
  1380		kvm_for_each_vcpu(i, vcpu, kvm)
> 1381			if (!mutex_trylock_nest_lock(&vcpu->mutex, &kvm->lock))
  1382				goto out_unlock;
  1383		return 0;
  1384	
  1385	out_unlock:
  1386		kvm_for_each_vcpu(j, vcpu, kvm) {
  1387			if (i == j)
  1388				break;
  1389			mutex_unlock(&vcpu->mutex);
  1390		}
  1391		return -EINTR;
  1392	}
  1393	EXPORT_SYMBOL_GPL(kvm_trylock_all_vcpus);
  1394	

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