linux-kernel - Re: [PATCH v3 7/8] KVM: x86/mmu: Protect rmaps independently with SRCU

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Date:   Fri, 7 May 2021 07:58:54 +0800
From:   kernel test robot <lkp@...el.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     kbuild-all@...ts.01.org, Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Kai Huang <kai.huang@...el.com>
Subject: Re: [PATCH v3 7/8] KVM: x86/mmu: Protect rmaps independently with
 SRCU

Hi Ben,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kvm/queue]
[also build test WARNING on tip/master linus/master next-20210506]
[cannot apply to linux/master v5.12]
[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]

url:    https://github.com/0day-ci/linux/commits/Ben-Gardon/Lazily-allocate-memslot-rmaps/20210507-024533
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: x86_64-randconfig-s021-20210506 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://github.com/0day-ci/linux/commit/dd56af97c1d2b22f9acd46d33c83ac5e7bf67acc
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Ben-Gardon/Lazily-allocate-memslot-rmaps/20210507-024533
        git checkout dd56af97c1d2b22f9acd46d33c83ac5e7bf67acc
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>


sparse warnings: (new ones prefixed by >>)
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse:    struct kvm_rmap_head [noderef] __rcu *
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse:    struct kvm_rmap_head *
   arch/x86/kvm/mmu/mmu.c: note: in included file (through include/linux/kvm_host.h, arch/x86/kvm/irq.h):
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
   arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
--
   arch/x86/kvm/x86.c:10926:17: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> arch/x86/kvm/x86.c:10926:17: sparse:    struct kvm_rmap_head [noderef] __rcu *
>> arch/x86/kvm/x86.c:10926:17: sparse:    struct kvm_rmap_head *
   arch/x86/kvm/x86.c: note: in included file (through include/linux/notifier.h, include/linux/memory_hotplug.h, include/linux/mmzone.h, ...):
   include/linux/srcu.h:182:9: sparse: sparse: context imbalance in 'vcpu_enter_guest' - unexpected unlock

vim +938 arch/x86/kvm/mmu/mmu.c

   929	
   930	static struct kvm_rmap_head *__gfn_to_rmap(struct kvm *kvm, gfn_t gfn,
   931						   int level,
   932						   struct kvm_memory_slot *slot)
   933	{
   934		struct kvm_rmap_head *head;
   935		unsigned long idx;
   936	
   937		idx = gfn_to_index(gfn, slot->base_gfn, level);
 > 938		head = srcu_dereference_check(slot->arch.rmap[level - PG_LEVEL_4K],
   939					      &kvm->srcu,
   940					      lockdep_is_held(&kvm->slots_arch_lock));
   941		return &head[idx];
   942	}
   943	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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