Re: [PATCH] virt/kvm avoids oops by adding parameter checking

[kbuild test robot]

Hi nixiaoming,

[auto build test ERROR on v4.13-rc6]
[also build test ERROR on next-20170901]
[cannot apply to kvm/linux-next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/nixiaoming/virt-kvm-avoids-oops-by-adding-parameter-checking/20170823-203000
config: mips-malta_kvm_defconfig (attached as .config)
compiler: mipsel-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mips 

All errors (new ones prefixed by >>):

   arch/mips/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_flush_remote_tlbs':
>> arch/mips/kvm/../../../virt/kvm/kvm_main.c:248:2: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
     long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
     ^~~~
   arch/mips/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_write_guest_offset_cached':
   arch/mips/kvm/../../../virt/kvm/kvm_main.c:2025:2: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
     gpa_t gpa = ghc->gpa + offset;
     ^~~~~
   cc1: all warnings being treated as errors

vim +248 arch/mips/kvm/../../../virt/kvm/kvm_main.c

d9e368d6 drivers/kvm/kvm_main.c Avi Kivity       2007-06-07  238  
a6d51016 virt/kvm/kvm_main.c    Mario Smarduch   2015-01-15  239  #ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
49846896 virt/kvm/kvm_main.c    Rusty Russell    2008-12-08  240  void kvm_flush_remote_tlbs(struct kvm *kvm)
2e53d63a virt/kvm/kvm_main.c    Marcelo Tosatti  2008-02-20  241  {
6f1ad410 virt/kvm/kvm_main.c    nixiaoming       2017-08-22  242  	if (kvm == NULL)
6f1ad410 virt/kvm/kvm_main.c    nixiaoming       2017-08-22  243  		return;
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  244  	/*
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  245  	 * Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  246  	 * kvm_make_all_cpus_request.
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  247  	 */
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13 @248  	long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
a086f6a1 virt/kvm/kvm_main.c    Xiao Guangrong   2014-04-17  249  
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  250  	/*
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  251  	 * We want to publish modifications to the page tables before reading
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  252  	 * mode. Pairs with a memory barrier in arch-specific code.
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  253  	 * - x86: smp_mb__after_srcu_read_unlock in vcpu_enter_guest
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  254  	 * and smp_mb in walk_shadow_page_lockless_begin/end.
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  255  	 * - powerpc: smp_mb in kvmppc_prepare_to_enter.
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  256  	 *
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  257  	 * There is already an smp_mb__after_atomic() before
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  258  	 * kvm_make_all_cpus_request() reads vcpu->mode. We reuse that
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  259  	 * barrier here.
4ae3cb3a virt/kvm/kvm_main.c    Lan Tianyu       2016-03-13  260  	 */
445b8236 virt/kvm/kvm_main.c    Tang Chen        2014-09-24  261  	if (kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
49846896 virt/kvm/kvm_main.c    Rusty Russell    2008-12-08  262  		++kvm->stat.remote_tlb_flush;
a086f6a1 virt/kvm/kvm_main.c    Xiao Guangrong   2014-04-17  263  	cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
2e53d63a virt/kvm/kvm_main.c    Marcelo Tosatti  2008-02-20  264  }
2ba9f0d8 virt/kvm/kvm_main.c    Aneesh Kumar K.V 2013-10-07  265  EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
a6d51016 virt/kvm/kvm_main.c    Mario Smarduch   2015-01-15  266  #endif
2e53d63a virt/kvm/kvm_main.c    Marcelo Tosatti  2008-02-20  267  

:::::: The code at line 248 was first introduced by commit
:::::: 4ae3cb3a2551b41f22284f713e7d5e2b61a85c1d KVM: Replace smp_mb() with smp_load_acquire() in the kvm_flush_remote_tlbs()

:::::: TO: Lan Tianyu <tianyu.lan@xxxxxxxxx>
:::::: CC: Paolo Bonzini <pbonzini@xxxxxxxxxx>

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